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110th

Penn Annual Conference

March 3 - 4, 2010 Philadelphia, Pennsylvania

PROCEEDINGS

110TH PENN ANNUAL CONFERENCE - 2010

Wednesday, March 3, 2010 Thursday, March 4, 2010 Philadelphia, Pennsylvania

TABLE OF CONTENTS

SPEAKERS

Speaker Biographies .............................................................................................................................................................. iv

PROCEEDINGS

COMPANION ANIMAL

Infectious Diseases

A1: A2: A3: A4: Feline Immunodeficiency Virus Update & Potpourri of Feline Infectious Diseases Chronic Draining Tracks and Nodules in Cats Feline Cholangitis: Update on Terminology & the Role of Bacteria Alice

SECTION A

Angela Mexas ..................................................... 1 olf............................................................ 4

Alice Wolf.......................................................... 10 Mark Rondeau .................................................. 12

Vaccinology

A5/6: Canine & Feline Vaccination: Protocols, Products and Problems A7: Effective Cancer Vaccines ­ A Promise or Pipe-Dream? Alice Wolf.......................................................... 16 Nicola Mason.................................................... 30

Behavior

B1: B2: B3: B4: Update on Human Directed Aggression Aggression Toward Unfamiliar Dogs on Walks Feline Aggression Toward Household Cats A Case-Based Approach to Elimination Problems in Cats

SECTION B

Debra Horwitz................................................... 35 Debra Horwitz................................................... 39 Debra Horwitz................................................... 42 Debra Horwitz................................................... 47

Dermatology

B5: B6: B7: Killing Bad Things: Bacteria Killing Bad Things: Mites and Insects Feline Viral Skin Diseases

SECTION B

Gregory C. Griffeth............................................ 52 Gregory C. Griffeth............................................ 55 Alice Wolf.......................................................... 61

Renal

C1: C2: C3: C4: C5: C6: C7: Evidence-Based Microalbuminuria Testing Update on Nephrotic Syndrome Treatment of Glomerular Diseases: Beyond ACE-Inhibitors Diagnostic & Therapeutic Approach to Crystals vs. Stones Staged Management of Chronic Kidney Disease Kracking Komplex Kidney Kases Diagnosis and Treatment of Systemic Hypertension

SECTION C

Barrak Pressler.................................................. 64 Barrak Pressler.................................................. 66 Barrak Pressler.................................................. 69 Barrak Pressler.................................................. 73 Scott A. Brown .................................................. 76 Scott A. Brown .................................................. 79 Scott A. Brown ....................................... .......... 82

PROCEEDINGS: Table of Contents

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110TH PENN ANNUAL CONFERENCE - 2010

Wednesday, March 3, 2010 Thursday, March 4, 2010 Philadelphia, Pennsylvania

COMPANION ANIMAL, cont.

Gastrointestinal Issues (sponsored by P&G PetCare)

D1: D2: D3: D4: D5: D6: D7: G.I. Motility Disorders Difficult Vomiting Disorders Canine Inflammatory Bowel Disease Infectious Gastrointestinal Disorders in Dogs and Cats Feline Exocrine Pancreatic Disease: A Diagnostic and Therapeutic Challenge Feline Hepatobiliary Disease: What's New in Diagnosis and Therapy Feline Diarrheal Syndromes: Common & Not-So-Common Disorders

SECTION D

Robert J. Washabau.......................................... 87 Robert J. Washabau.......................................... 94 Robert J. Washabau.......................................... 98 Robert J. Washabau........................................ 106 Robert J. Washabau........................................ 117 Robert J. Washabau........................................ 129 Robert J. Washabau........................................ 133

Dermatology

E1: E2: E3: E4: Food Allergies: What You Know, What You Don't Know, and What You Should Know Canine Otitis Externa: Controversies, Concepts and New Approaches Dermatologic Pearls: Updates on Practical Clinical Tips Killing Bad Things: Fungi

SECTION E

Anthony Yu ..................................................... 137 Anthony Yu ..................................................... 143 Anthony Yu ..................................................... 147 Gregory C. Griffeth.......................................... 152

Immune-Mediated Diseases

E5: E6: E7: IMHA & IMT SIRS, MODS and Sepsis: Pathophysiology and Diagnosis SIRS, MODS and Sepsis: Treatment, Monitoring and Case Examples

SECTION E

Mary Beth Callan ............................................ 158 Erica Reineke .................................................. 163 Deborah Silverstein......................................... 167

Dentistry and Oral Surgery (sponsored by Pfizer Animal Health)

F1: F2: F3: F4: F5: F6: F7: Energize Your Hospital's Dentistry Services Recognizing Common Oral Pathology Diets, Treats, Antibiotics and Vaccinations: Preventing Dragon Breath Feline Stomatitis: What Works? Dental Extractions Made Easier Dealing With Fractured Faces Practical Approach to Oral Tumors

SECTION F

Bonnie Miller .................................................. 172 Alexander Reiter ............................................. 174 Colin Harvey.................................................... 179 Alexander Reiter ............................................. 184 Alexander Reiter ............................................. 186 Alexander Reiter ............................................. 189 Alexander Reiter ............................................ 193

PROCEEDINGS: Table of Contents

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110TH PENN ANNUAL CONFERENCE - 2010

Wednesday, March 3, 2010 Thursday, March 4, 2010 Philadelphia, Pennsylvania

VETERINARY TECHNICIAN

SECTION G1

G1-1: Blastomycosis G1-2: Hemostasis G1-3: Neonatal Resuscitation and Nursing Care G1-4: Injectable Drug Incompatibilities and Interactions G1-5: Small Animal Dermatology: The Itch and the Scratch G1-6: Anesthesia in the Critical Patient G1-7: A Tail of Two Kidneys: Keeping our Renal Transplant Recipients Infection Free Amy Lynn Barr ............................................ NONE Amy Lynn Barr ............................................ NONE Amy Lynn Barr ............................................ NONE Amy Lynn Barr ............................................ NONE Colleen Walters-Pinney .................................. 197 Amy Henderson .............................................. 200 Lynne Beale..................................................... 204

SECTION G2

G2-1/2: Equine Colitis from a Nursing Standpoint: Part 1 G2-3: The Broad Realm of Clostridium G2-4: Equine Infectious Respiratory Diseases: Containment, Cleaning & Control G2-5: Common Neurologic Disorders of the South American Camelid G2-6: Crypto: Calves, Control, Prevention...and You! G2-7: Stop the Spread: Biosecurity in Laboratory Animal Science Christopher Rizzo ............................................ 208 Jamie DeFazio ................................................. 212 Barbara Dugan ............................................... 217 Barbara Dugan ............................................... 222 Sarah Dell ................................................... NONE Mary Goldy & Jennifer Kirsch.......................... 226

EQUINE

SECTION H1

H1-1: It's All in Your Truck! Advanced Internal Medicine Diagnostics for the Ambulatory Vet H1-2: Introduction to Evidence Based Medicine H1-3: Practicing Veterinary Evidence Based Medicine H1-4: Epidemiology and Treatment of Rhodococcus Equi Pneumonia H1-5: Control and Prevention of Rhodococcus Equi Pneumonia H1-6: Bumps, Scratches and Heaves, Oh My! Update on the Diagnosis of Atopy H1-7: Pot Pourrit for Horse Skin: Diagnosis and Management of Equine Dermatologic Disorders Maeva May..................................................... 233 Noah Cohen .................................................... 240 Noah Cohen .................................................... 243 Noah Cohen .................................................... 248 Noah Cohen .................................................... 252 Anthony Yu ..................................................... 254 Anthony Yu ..................................................... 257

SECTION H2

H2-1: Fever of Unknown Origin: A Diagnostic Plan H2-2: Preventing Laminitis in Horses with Inflammatory Diseases H2-3: Blood and Plasma Transfusion Therapy in Horses and Foals H2-4: Talking to Horse Owners About Anthelmintic Resistance H2-5: Equine Proliferative Enteropathy (Lawsonia Intracellularis: Diagnosis and Treatment) H2-6: Leptospirosis in Horses H2-7: EPM or Not? Differentiating Between Other Equine Problems Thomas Divers ................................................ 291 Thomas Divers ................................................ 293 Amy Johnson................................................... 296 Joan Norton .................................................... 279 Thomas Divers ................................................ 281 Thomas Divers ................................................ 284 Rose Nolan-Walston ....................................... 288

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110TH PENN ANNUAL CONFERENCE - 2010

Wednesday, March 3, 2010 Thursday, March 4, 2010 Philadelphia, Pennsylvania

SPEAKER BIOGRAPHIES

Amy Lynn Barr, LVT, VTS (ECC) ICU Department Coordinator - Burlington Emergency and Veterinary Specialists Williston, VT Ms. Barr became Vermont's first and only veterinary technician specialist when she passed the Academy of Veterinary Emergency and Critical Care Technicians exam in 2005. Her veterinary nursing career has been focused exclusively in the fields of emergency and critical care for the past 10 years. She also has more than 18 years experience as a wildlife rehabilitator. Her interests include hematology, cytology, infusion nursing, pulmonology and neonatal care. Lynn Beale, CVT Renal Transplant Coordinator & Nurse - Matthew J. Ryan Veterinary Hospital University of Pennsylvania, School of Veterinary Medicine Philadelphia, PA Ms. Beale joined the Renal Transplant Program in July of 2007. She is originally from New York, where she completed her licensure at Suffolk County Community College on Long Island. She began her career in veterinary medicine working as a nurse at North Shore Animal League's Alex Lewyt Veterinary Medical Center, where she worked in shelter animal medicine. Timothy J. Beck Senior Extension Educator Dairy Business Management - Penn State Cooperative Extension Carlisle, PA Timothy Beck received his BS in Animal Science from Penn State University in 1982 and his master's degree in 1991 from Kansas State University. After graduating from Kansas State, he held the position of County Extension Agent in Fredonia, Kansas. Tim returned to Pennsylvania in 1991 to continue his work within dairy herd management and dairy farm business management. Throughout his 23 years in dairy management he has been a member of state committees, been involved in the development of several key programs, including the PA Dairy Tool, and conducted many workshops. Scott A. Brown, VMD, PhD, DACVIM Department Head, Small Animal Medicine and Surgery University of Georgia, College of Veterinary Medicine Winterville, GA Dr. Brown received his veterinary degree in 1982 from the University of Pennsylvania School of Veterinary Medicine. He is presently the Josiah Meigs Distinguished Professor at the University of Georgia College of Veterinary Medicine and is an internationally recognized expert in nephrology and systemic hypertension, having published more than 150 research articles and book chapters on related topics. Dr. Brown has also been recognized for excellence in research and teaching, and has received numerous awards including the AVMA Excellence in Research Award, the Royal Canin Award and the National Norden Distinguished Teacher Award. Mary Beth Callan, VMD, DACVIM Associate Professor of Medicine - Matthew J. Ryan Veterinary Hospital University of Pennsylvania, School of Veterinary Medicine Philadelphia, PA Dr. Callen graduated from the University of Pennsylvania School of Veterinary Medicine, where she also completed an internship, internal medicine residency and hematology/transfusion medicine fellowship. Her clinical research interests include hemostatic disorders, particularly platelet disorders and transfusion medicine.

PROCEEDINGS: Speaker Biographies

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110TH PENN ANNUAL CONFERENCE - 2010

Wednesday, March 3, 2010 Thursday, March 4, 2010 Philadelphia, Pennsylvania

Noah Cohen, VMD, MPH, PhD, DACVIM Professor, Large Animal Clinical Sciences Texas A&M University, College of Veterinary Medicine and Biomedical Sciences College Station, TX Dr. Cohen graduated from the University of Pennsylvania School of Veterinary Medicine in 1983. He spent two years in private equine practice in the Toronto, Ontario area and then enrolled at Johns Hopkins University School of Hygiene and Public Health. After completing his MPH (1986) and PhD (1989) degrees at Johns Hopkins, he then completed a residency in large animal internal medicine at Texas A&M University, where he is currently director of the Equine Infectious Disease Laboratory. Jamie DeFazio, CVT Nursing Supervisor - New Bolton Center University of Pennsylvania, School of Veterinary Medicine Kennett Square, PA Ms. DeFazio graduated from Harcum College, in Bryn Mawr, PA, in 2000 with a degree in veterinary technology. Throughout her career she has worked in small animal, large animal and exotic practice, and the majority of her career has been at Penn Vet's New Bolton Center. She also lectures at Harcum College and is on the boards of AAEVT and PVTA, the latter of which named her the 2009 Pennsylvania Veterinary Technician of the Year. Sarah Dell, CVT Veterinary Technician - New Bolton Center University of Pennsylvania, School of Veterinary Medicine Kennett Square, PA Ms. Dell is a certified veterinary technician originally from Martinsburg, PA where she grew up on her parents' 200-cow dairy farm. She worked as a veterinary assistant for an ambulatory large animal veterinary service assisting with herd checks, bovine surgery and other diverse veterinary cases. In 2006, Sarah graduated from Harcum College in Bryn Mawr, PA as a veterinary technician and currently teaches a Veterinary Parasitolgoy Lab at the school. Thomas Divers, DVM, DACVIM, DACVECC Chief, Section of Large Animal Medicine Cornell University, College of Veterinary Medicine Ithaca, NY Dr. Divers, a Virginia native, received his DVM from the University of Georgia. He completed an internship at the University of California at Davis and a residency in large animal medicine and ambulatory medicine at the University of Georgia, where he was eventually a member of the large animal medicine faculty. He spent ten years at Penn Vet's New Bolton Center prior to his current position at Cornell University, where he has been teaching for the past 19 years. Dr. Divers' research has focused on medical diseases of horses and dairy cattle. Barbara Dugan, CVT Veterinary Technician - New Bolton Center University of Pennsylvania, School of Veterinary Medicine Kennett Square, PA Ms. Dugan graduated from Manor College in 2002. After a short time, she worked as a small animal surgical nurse, but found her true calling in large animal medicine. For the last eight years she has worked with a variety of large animal patients at Penn Vet's New Bolton Center. She is also currently the instructor for the Large Animal Clinical and Emergency Procedures course for the Veterinary Technology Program at Manor College.

PROCEEDINGS: Speaker Biographies

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110TH PENN ANNUAL CONFERENCE - 2010

Wednesday, March 3, 2010 Thursday, March 4, 2010 Philadelphia, Pennsylvania

James D. Ferguson, VMD, DACT, DACVN Section Chief, Nutrition & Animal Health Economics - New Bolton Center University of Pennsylvania, School of Veterinary Medicine Kennett Square, PA Dr. Ferguson graduated from the University of Pennsylvania School of Veterinary Medicine in 1981 and has been a professor of Clinical Nutrition at Penn Vet's New Bolton Center since 1996. His primary areas of research include the relationship between nutrition and manure nutrient content and efficient recycling of nutrients on dairy farms and the development of computer models to aid in farm management of nutrition, nutrient management and reproduction. David T. Galligan, VMD, MBA Professor, Animal Health Economics - New Bolton Center University of Pennsylvania, School of Veterinary Medicine Kennett Square, PA Dr. Galligan received his degree from the University of Pennsylvania's School of Veterinary Medicine in 1981 and afterwards entered dairy practice in Gap, PA. He returned to Penn Vet in 1982 as a resident in dairy nutrition and, in 1985, received his MBA from the Wharton School with a major in decision sciences. Dr. Galligan was a founding member of the Avon Grove Charter School in West Grove, PA, served on its board for six years and is currently president of its Foundation Board. His academic studies focus on the economic valuation of veterinary and management interventions on dairy farms. Mary Goldy, BA, MLAS Veterinary Technician, Anesthesia - Matthew J. Ryan Veterinary Hospital University of Pennsylvania, School of Veterinary Medicine Philadelphia, PA Ms. Goldy received her bachelor's degree in biology from the Richard Stockton College of New Jersey and her master's degree in laboratory animal science from Drexel University in Philadelphia, PA. She worked as a veterinary technician for the Galloway Animal Hospital, Rothman Animal Hospital and the Gorman Cardiovascular Research Group, and currently works at Penn Vet in the University Laboratory Animal Research Department. Gregory C. Griffeth, DVM, DACVD Staff Dermatologist - Matthew J. Ryan Veterinary Hospital University of Pennsylvania, School of Veterinary Medicine Philadelphia, Pennsylvania Dr. Griffeth earned his DVM in 2004 from Louisiana State University, completed an internship in small animal medicine and surgery at the University of Tennessee in 2005, and completed a residency in dermatology and allergy at Penn Vet in 2007. After two years at a private practice in Portland, OR, he returned to Penn Vet in 2009 as a practicing and teaching dermatologist. Dr. Griffeth, a consultant for the Veterinary Information Network, also reviews and edits publications on the topic of resistant infections. Colin Harvey, BVSc, FRCVS, DipACVS, DipAVDC Professor, Surgery and Dentistry ­ Matthew J. Ryan Veterinary Hospital University of Pennsylvania, School of Veterinary Medicine Philadelphia, PA Dr. Harvey graduated from the University of Bristol Veterinary School and completed an internship and residency in small animal surgery at the University of Pennsylvania School of Veterinary Medicine, where he later served as Chief, Section of Small Animal Surgery, and Vice-Chair, Department of Clinical Studies. Dr. Harvey, former president and current Executive Secretary of the American Veterinary Dental College, has received many awards including the Norden Distinguished Teacher Award and the Peter Emily Award for Outstanding Contributions to Veterinary Dentistry.

PROCEEDINGS: Speaker Biographies

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110TH PENN ANNUAL CONFERENCE - 2010

Wednesday, March 3, 2010 Thursday, March 4, 2010 Philadelphia, Pennsylvania

Amy Henderson, CVT Veterinary Technician, Anesthesia - Matthew J. Ryan Veterinary Hospital University of Pennsylvania, School of Veterinary Medicine Philadelphia, PA Ms. Henderson graduated from Bel-Rea Institute of Animal Technology in 2002. She worked in a small animal and exotic practice in Denver, CO before moving to Pennsylvania to work at a busy VCA practice in Neshaminy, PA for two years. In 2005, she joined the staff at the Ryan Veterinary Hospital as an anesthesia technician. Debra Horwitz, DVM, DACVB Veterinary Behavior Consultations St. Louis, MO Dr. Horowitz received her DVM from Michigan State University College of Veterinary Medicine. She has had a behavior referral practice since 1982, and her practice is presently located in St. Louis, MO. She is an adjunct faculty member at the University of Missouri College of Veterinary Medicine and also serves as a behavioral consultant for the Veterinary Information Network. In 1999, Dr. Horowitz received the Excellence in Companion Animal Behavior award and was named the Technician Speaker of the Year at the North American Veterinary Conference. She is a frequent lecturer in both North America and abroad on behavioral topics to veterinarians and pet owners, and often featured on both television and radio. Amy L. Johnson, DVM, DACVIM-LAIM Lecturer, Clinical Studies - New Bolton Center University of Pennsylvania, School of Veterinary Medicine Kennett Square, PA Dr. Johnson graduated from Cornell University in 2003 and performed an internship at B.W. Furlong and Associates, a private equine hospital in Oldwick, NJ, and then returned to Cornell for a large animal internal medicine residency. After obtaining board certification, Dr. Johnson was hired as a lecturer at Penn Vet's New Bolton Center and is currently in the process of completing a second ACVIM residency in neurology. Her research interests include equine neurologic diseases such as botulism and equine protozoal myeloencephalitis. Jennifer Kirsch, BA, RLATG Senior Anesthesia Veterinary Technician Specialist - Matthew J. Ryan Veterinary Hospital University of Pennsylvania, School of Veterinary Medicine Philadelphia, PA Ms. Kirsch has worked in the veterinary medical field since 2000 and has been involved in laboratory animal science since 2006. She received her bachelor's degree from Temple University in 2004 and currently works in the University Laboratory Animal Resources (ULAR) department at Penn Vet. She is a member of the Institutional Animal Care and Use Committee at Delaware Valley College and a member of both the National and Delaware Valley Branch of the American Association of Laboratory Animal Science. Nicola Mason, BVM, PhD, DACVIM Assistant Professor, Medicine and Pathobiology University of Pennsylvania, School of Veterinary Medicine Philadelphia, PA Dr. Mason received her veterinary degree from the Royal Veterinary College, University of London, performed a small animal internship at the University of Bristol and an internal medicine residency at the University of Pennsylvania. She then received her PhD in immunology at Penn and performed her post doctoral fellowship in the laboratory of Dr. Carl June at the Abramson Family Cancer Research Institute at Penn's School of Medicine. She joined Penn Vet's faculty as an assistant professor in the Departments of Pathobiology and Clinical Studies in 2006 and is currently the director of the Penn Vet Tumor Tissue Bank and the associate director of Translational Research at the Mari Lowe Center for Comparative Oncology.

PROCEEDINGS: Speaker Biographies

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110TH PENN ANNUAL CONFERENCE - 2010

Wednesday, March 3, 2010 Thursday, March 4, 2010 Philadelphia, Pennsylvania

Maeva May, DVM Resident, Clinical Studies - New Bolton Center University of Pennsylvania, School of Veterinary Medicine Kennett Square, PA Dr. May, after spending the first seven years of her life in France, claimed Raleigh, NC as her home for the following 18 years. After graduating from North Carolina State University, she completed an internship at Rood and Riddle Equine Hospital in Lexington, KY. She also worked as an ambulatory veterinarian in Ocala, FL, where her interest in infectious diseases prompted her to complete a fellowship in vaccinology at Cornell University, focusing on the design and development of novel vaccines for Equine Herpes Virus type 1. Angela Mexas, DVM, PhD, DACVIM Research Investigator - Pathology & Laboratory Medicine University of Pennsylvania Health System Philadelphia, PA Dr. Mexas earned her DVM from Colorado State University in 1999. She completed a residency in small animal internal medicine at North Carolina State University where in 2007 she received her PhD in immunology. Dr. Mexas has received many awards over the years including most recently the Mentored Clinical Scientist Research Career Development Award (K08) in 2007. Kathryn Michel, DVM, MS, DACVN Associate Professor, Nutrition - Matthew J. Ryan Veterinary Hospital University of Pennsylvania, School of Veterinary Medicine Philadelphia, PA Dr. Michel graduated from the Cummings School of Veterinary Medicine at Tufts University in 1983. She completed a residency in small animal clinical nutrition and a master's degree at the University of Pennsylvania School of Veterinary Medicine, followed by a postdoctoral fellowship with the Nutrition Support Service at Penn's School of Medicine. Her research interests include nutritional assessment, nutritional requirements of hospitalized companion animals and nutrient modulation of GI and endocrine diseases. Bonnie Miller, RDH, BS Staff Dental Hygienist - Matthew J. Ryan Veterinary Hospital University of Pennsylvania, School of Veterinary Medicine Philadelphia, PA With 20 years experience in her role at the University of Pennsylvania, Bonnie Miller is active in clinical dental cases and research projects. She is a guest lecturer in the veterinary core dental course and teaches dental rounds and wet labs to students. Bonnie is founder of VetDent CE Associates, a company which provides on-line dental seminars. She is a member of the American Veterinary Dental Society, and in 1996, was recognized at the National Veterinary Dental Forum for her contributions to the field. Rose Nolen-Walston, DVM Assistant Professor of Medicine - New Bolton Center University of Pennsylvania, School of Veterinary Medicine Kennett Square, PA Dr. Nolen-Walston grew up in England and moved to the US as a teenager. She completed her DVM at the University of Georgia, and an internship and residency in equine internal medicine at Tufts University. She also completed a research fellowship before joining the Penn Vet faculty in 2006. Her clinical and research interests are predominantly in equine pulmonology, including diagnostics and therapeutic options for Inflammatory Airway Disease.

PROCEEDINGS: Speaker Biographies

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110TH PENN ANNUAL CONFERENCE - 2010

Wednesday, March 3, 2010 Thursday, March 4, 2010 Philadelphia, Pennsylvania

Joan Norton, VMD Resident, Clinical Studies - New Bolton Center University of Pennsylvania, School of Veterinary Medicine Kennett Square, PA Ms. Norton graduated from Worcester Polytechnic Institute with a degree in biotechnology and received her veterinary degree from the University of Pennsylvania School of Veterinary Medicine. She completed an internship at Rood and Riddle Equine Hospital in Lexington, KY and is currently a third-year resident at Penn Vet's New Bolton Center with strong interests in diagnostics and critical care medicine. Her research interests include monitoring the critical care patient with the use of central venous pressure and stall side diagnostics for gastric and colonic ulcers. Barrak Pressler, DVM, PhD, DACVIM Assistant Professor, Small Animal Internal Medicine Purdue University, School of Veterinary Medicine West Lafayette, IN Dr. Pressler earned his DVM from the University of California at Davis in 1999 and his PhD in immunology from North Carolina State University in 2008. In addition to being a professor at Perdue, he is also the principal investigator in the Comparative Nephrology Laboratory and a Young Investigator Fellow in the Indiana Comparative and Translational Sciences Institute. His primary clinical and basic science interests are veterinary nephrology and urology, particularly the pathogenesis and immune dysfunction of glomerular and autoantibody diseases. Erica Reineke, VMD Assistant Professor, Emergency & Critical Care Medicine - Matthew J. Ryan Veterinary Hospital University of Pennsylvania, School of Veterinary Medicine Philadelphia, PA Dr. Reineke graduated from the University of Pennsylvania School of Veterinary Medicine in 2002 where she continued and completed an internship and residency in emergency and critical care medicine. Her current research interests include continuous glucose monitoring and glycemic control. Alexander Reiter, Dipl. Tzt., Dr. med. vet., DAVDC, EVDC Assistant Professor & Chief, Dentistry and Oral Surgery Service Matthew J. Ryan Veterinary Hospital University of Pennsylvania, School of Veterinary Medicine Philadelphia, PA Dr. Reiter graduated from the University of Veterinary Medicine in Vienna, Austria, in 1996 and spent over a year in companion animal practice in Phoenix, AZ prior to completing his residency in dentistry and oral surgery at the University of Pennsylvania School of Veterinary Medicine. Following a three-year lectureship and completion of a postgraduate thesis, he joined the standing faculty of Penn Vet in 2003. Dr. Reiter was the recipient of the 2004 European Veterinary Dental Society Award and the 2006 American Veterinary Dental Society/Hill's Award. Christopher Rizzo, LVT Veterinary Nurse - New Bolton Center University of Pennsylvania, School of Veterinary Medicine Kennett Square, PA Christopher received his associate's degree in veterinary technology from Camden County College in 2005. Prior to graduation, he was employed in New York City at the Veterinary Emergency Center. He also spent two foaling seasons at Mid Atlantic Equine Medical Center in Ringoes, NJ as a foal nurse. Mr. Rizzo, a Unionville, PA resident, maintains a small local farm where he cares for several of his own horses and boarders.

PROCEEDINGS: Speaker Biographies

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110TH PENN ANNUAL CONFERENCE - 2010

Wednesday, March 3, 2010 Thursday, March 4, 2010 Philadelphia, Pennsylvania

Mark Rondeau, DVM, DACVIM Staff Veterinarian and Lecturer - Matthew J. Ryan Veterinary Hospital University of Pennsylvania, School of Veterinary Medicine Philadelphia, PA Dr. Rondeau received his DVM from Tufts University in Massachusetts in 1999. After completing an internship in small animal medicine and surgery at the VCA South Shore Animal Hospital in Massachusetts, he joined Penn Vet in 2000 to complete a two-year residency in small animal internal medicine. He has written several original papers, chapters and abstracts for professional peer-reviewed publications. Deborah Silverstein, DVM, DACVECC Assistant Professor, Critical Care ­ Matthew J. Ryan Veterinary Hospital University of Pennsylvania, School of Veterinary Medicine Philadelphia, PA Dr. Silverstein earned her DVM from the University of Georgia in 1997 then completed a rotating internship in small animal medicine and surgery, followed by a residency in emergency and critical care medicine at the University of California at Davis. Her research interests include the management and monitoring of sepsis in small animals, specifically shock fluid therapy, vasopressin therapy, assessment of the microcirculation and markers of vascular leak syndromes. Billy I. Smith, DVM, MS, DABVP-FA Assistant Professor, Field Service - New Bolton Center University of Pennsylvania, School of Veterinary Medicine Kennett Square, PA Dr. Smith received a BS in diary production science and a DVM at Louisiana State University. After graduation, he completed an internship program at Utah State University and a residency program in production medicine at the University of Florida, where he also received an MS in veterinary science. He was a staff veterinarian for Aurora Dairy Corporation, where he led animal health and dairy management for three large southeastern dairies and has been awarded numerous grants for a variety of research projects over the years. Colleen Walters-Pinney, CVT Nurse Practitioner, Dermatology and Allergy - Matthew J. Ryan Veterinary Hospital University of Pennsylvania, School of Veterinary Medicine Philadelphia, PA Ms. Walters-Pinney has 11 years experience with the diagnostics and treatment of skin and ear disease as well as the training of veterinary students and dermatology residents. Robert J. Washabau, VMD, PhD, DACVIM Professor of Medicine & Department Chair, Veterinary Clinical Sciences University of Minnesota, College of Veterinary Medicine St. Paul, MN Dr. Washabau received his dual VMD/PhD from the University of Pennsylvania in 1982. He then completed an internship at Penn Vet and a residency in internal medicine at the University of California at Davis. He held the appointments of assistant, associate, and full professor of medicine at Penn Vet (1989-2004) before being recruited to the University of Minnesota where he currently teaches, practices and performs research in gastroenterology and gastrointestinal physiology. Dr. Washabau is currently the chair of the International Gastrointestinal Standardization Group and recently received the WSAVA International Scientific Achievement Award (2009).

PROCEEDINGS: Speaker Biographies

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110TH PENN ANNUAL CONFERENCE - 2010

Wednesday, March 3, 2010 Thursday, March 4, 2010 Philadelphia, Pennsylvania

Alice Wolf, DVM, DACVIM, DABVP Chief Medical Consultant - Veterinary Information Network Adjunct/Emeritus Professor - Texas A&M University, College of Veterinary Medicine College Station, TX Dr. Wolf received her DVM from the University of California at Davis, interned at Angell Memorial Animal Hospital in Boston, MA and returned to U C Davis for her residency in small animal internal medicine. She spent three years in private practice in Albany, CA and the next 24 years as a professor of small animal medicine at Texas A&M University. She has received a number of teaching and service awards and has been recognized for her contributions in feline internal medicine with the AAHA Regional Practitioner of the Year Award and the prestigious Bourgelat Award from the British Small Animal Veterinary Association. Anthony Yu, DVM, MS, DACVD Associate Professor, Dermatology University of Guelph, Ontario Veterinary College Guelph, ON, Canada After finishing a combined master's and dermatology residency at Auburn University in Alabama in 1995, Dr. Yu started his first private dermatology referral practice in Portland, OR. Within his 11 years in Oregon, Dr. Yu dealt with chronic ear, skin and allergic conditions in dogs, cats and horses. In 2004, he returned to Ontario Veterinary College, his alma mater, as a part-time associate professor in veterinary dermatology and became full-time in 2006.

PROCEEDINGS: Speaker Biographies

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110TH PENN ANNUAL CONFERENCE - 2010

Wednesday, March 3, 2010 Thursday, March 4, 2010 Philadelphia, Pennsylvania

COMPANION ANIMAL: Infectious Diseases

FELINE IMMUNODEFICIENCY VIRUS

Angela Mexas, DVM, PhD, DACVIM

Research Investigator, Pathology & Laboratory Medicine University of Pennsylvania Health System Philadelphia, PA

INTRODUCTION

Feline Immunodeficiency Virus has evolved from being considered a death sentence at animal shelters and rescue missions to becoming a manageable chronic illness in domestic cats. Understanding the life cycle of the virus and the pathogenesis of the disease is critical in choosing appropriate diagnostic tools and treatment options. FIV is a retrovirus, lentivirus associated with immunodeficiency syndromes in domestic cats. It is believed to have been present in wild felids for a very long time and has evolved in these hosts to cause very little if any immunodeficiency at all. It is classified as a retrovirus because it carries two copies of its genome in the RNA form along with a reverse transcriptase enzyme. Lentiviruses are so classified because they cause latent disease with slow progression over time. Understanding the life cycle of viral particles in host cells is important to veterinarians because we constantly have to evaluate new information regarding diagnostic tests and anti-retroviral drugs. Because FIV is closely related to the Human Immunodeficiency Virus (HIV) associated with AIDS, we are bombarded with a wealth of information on pathogenesis and treatment options and left with the responsibility of understanding important differences between the human and feline pathogens. As companies and research institutions spend millions of dollars developing new therapeutic options for people with HIV, veterinarians must remain cautiously optimistic that some of these therapies will be useful to us as effective, affordable, and safe treatments for FIV positive cats. Selecting the best candidates for translation into feline medicine will require a thorough evaluation of the treatments' mechanism of action and role in disease prevention. Steps in the viral life cycle include binding, fusion, reverse transcription, integration, protein processing, particle assembly, budding and release. Each of these steps can be targeted therapeutically to reduce viral replication and minimize disease progression. However, current therapies are unable to eradicate integrated viral copies from host cells, so they do not offer a cure. It has been shown in human clinical trials, that targeting more than one step of the viral cycle at a time is imperative in slowing down the development of drug resistance, to delay disease progression. This approach is achieved in human medicine by administering so called "drug cocktails" made up of combinations of drugs that target different steps in the viral cycle all at once. This is necessary because these viruses undergo a high rate of mutations at every viral cycle, resulting in their ability to evade immunologic control and drug effects very quickly. Unfortunately, only two classes of anti-viral therapies have been evaluated for use in cats, and many others target areas that will not apply to FIV therapy. As we discuss each part of the viral life cycle and disease progression we will touch on what is known about treatment options that target these steps.

VIRAL LIFE CYCLE

Viral binding is the process of attachment between a virus particle and the host cell it will infect. This step involves recognition of viral surface proteins by cell surface receptors. The type of viral surface protein present on the viral capsid and the expression of protein receptors on the cell membrane determine which type of cells will be susceptible to infection. Thus, infection with FIV is limited largely to lymphocytes and macrophages, because these cells express the receptors the virus can bind to. There are important differences in the receptor molecules used by FIV and HIV that will limit our ability to use drugs developed for HIV in FIV infected cats. In fact, this is one of the most important differences between FIV and HIV as it has implications not only in drug resistance, but also pathogenesis and the establishment of viral reservoirs. HIV uses the CD4 receptor expressed primarily on T lymphocytes as a primary receptor. Other cells including monocytes and dendritic cells also express this receptor and may play a minor role in HIV. In addition, binding of HIV requires the interaction of surface proteins with secondary or co-receptor molecules. In the case of HIV, CCR5 is the most important coreceptor and CXCR4 can also play a role in some individuals and certain viral strains. In contrast, FIV uses CD134 (otherwise known as OX40) as a primary receptor and CXCR4 as its co-receptor molecule and these receptors are upregulated in activated CD4+ T cell lymphocytes, making these the most susceptible cells to viral infection. Thus, many of the drugs developed against HIV that target CD4 or CCR5 binding to prevent viral entry will be of no use in veterinary medicine. For example, Maraviroc (brand-named Selzentryz) which targets CCR5 specifically, is one such compound that is effective in HIV but cannot be applied to FIV disease because it targets a receptor that FIV does not use. In contrast, compounds that target

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110TH PENN ANNUAL CONFERENCE - 2010

Wednesday, March 3, 2010 Thursday, March 4, 2010 Philadelphia, Pennsylvania

CXCR4 are currently under investigation and may provide therapeutic effects against both HIV and FIV. One such compound, AMD3100, has shown great promise during in-vitro experiments and was most recently shown to improve clinical signs and reduce proviral loads in naturally infected FIV-positive cats. The drug was administered at 0.5 mg/kg q12 hrs SC for 6 weeks. Side effects were not noted, but long-term responses or effects were not evaluated. This compound is not yet licensed for clinical use but shows great promise for the near future. Viral fusion and entry are subsequent steps involved in the infection of HIV or FIV into host cells. Once the viral proteins bind to cell receptors, conformational changes in both the surface of the virus and the cell membrane occur that result in the release of viral proteins, and genomic material into the host cell. This process is still under investigation and new evidence suggests endocytosis is involved in viral entry of HIV. Drugs commonly used in human therapy that target this step include Enfurvitide, a compound that binds to viral protein gp41 and interferes with its ability to fuse the viral and cellular membranes together preventing the entry of viral contents in the host cell. While studies comparing the structure and function of analogous compounds in FIV viral entry have been performed, and show a high degree of homology and response to these compounds in vitro, no clinical recommendations have been forthcoming regarding the use of fusion inhibitors in FIV. The most commonly used antiviral drug in feline practice and the only one that has been tested clinically and is approved for extra-label use is AZT (3'-azido-2',3'-dideoxythymidine), a nucleoside analog that interferes with reverse transcription. Once the viral capsid has bound to the cell surface, fused with the cell membrane and released its contents into the host cell, the process of reverse transcription is involved in converting the viral genome from its RNA form into DNA that can be integrated in the host genome. The enzyme reverse transcrptase is responsible for this process, but insertion of nucleoside analogues, such as AZT, prevent the production of viral cDNA. AZT (zidovudine) has been evaluated in clinical trials in cats and has been shown to reduce plasma viral loads, improve clinical status, and be safe in the treatment of cats with FIV. A common side effect includes development of non-regenerative anemia that must be monitored for through the evaluation of routine CBC's while on therapy, and the drug should be discontinued if a drop in the hematocrit of more than 20% is noted. The recommended dose is 5-10 mg/kg q12 hrs PO or SC. Side effects are more common at the higher doses. The use of AZT in veterinary medicine has been most inhibited by its high cost. New, similar compounds aimed at decreasing the side effects while maintaining efficacy are currently under evaluation. Integrase inhibitors block the next step in the viral life cycle. Once cDNA is made out of viral RNA, it can be introduced into the hosts chromosomal DNA so that the cells' machinery can be used to produce new viral particles. Integrase inhibitors such as Raltegravir (Isentress) have recently been approved for clinical use in human medicine and been shown to aid in the maintenance of low viral loads and high CD4 T cell counts. Integrase inhibitors have not been evaluated for use in veterinary medicine, but based on their efficacy in human medicine, analogous compounds should be developed and studied for cats with FIV. Protease inhibitors are also commonly used in HIV therapy. After DNA integration, the cells' machinery is employed in the transcription and translation of viral RNA and proteins (respectively). Following translation proteins need to be cleaved into functional units and assembled into new viral particles. Protease inhibitors have been designed to block this step and have been used successfully in the clinic, but veterinary studies are lagging. New information is emerging in HIV research regarding cell factors involved in the inhibition of several steps in the viral life cycle. While FIV is well recognized as a useful and important model for HIV infection because many of the pathologic and immunologic features of infection and disease are similar, more research in FIV is needed to determine what therapeutic targets can be applied to cats in practice.

DISEASE PROGRESSION

The feline immunodeficiency virus (FIV) infection of domestic cats is a well-established model for the study of infections with human immunodeficiency virus (HIV) and the related immunodeficiency syndrome (AIDS). Both HIV and FIV infections are characterized by a short acute phase with high but self-limiting viremia, followed by a long latent subclinical phase with low viremia. Most infected humans and felines subsequently progress into a phase of severe immunodeficiency, which is manifested in opportunistic infections or lympho-proliferative diseases. Immunologically, the acute phase of infection is characterized by humoral and T cell-mediated anti-viral immune responses that correlate with a sharp decrease in plasma viremia. However, evidence suggests that the immune response to the virus is lost during the acute phase of infection.

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Understanding the phases of disease and the immunologic response to infection may help the veterinarian interpret diagnostic test results and make decisions regarding how and when to test suspect cats for FIV. The most common route of infection in naturally occurring feline disease is through bite wounds. The virus is highly concentrated in the saliva of infected cats and easily transmitted to the circulation of a negative cat following an attack. Therefore, intact males (with a high propensity for fighting) with outdoor access are at greatest risk for acquiring infection with FIV. While cats have been experimentally infected trans-mucosally in research arenas and vertical transmission has occasionally been observed, these modes of transmission are thought to be rare in naturally occurring disease. This is another key difference between FIV and its human counterpart because much of the effort in prevention of HIV is aimed at the production of anti-viral agents that would reduce infection through sexual contact. Following infection there is a short period of intense viral replication that results in high plasma viral loads, temporary clinical signs (which often go unrecognized in cats) and variable immunologic responses by the host. In fact innate, humoral and cell mediated mechanisms are activated early on to reduce and control plasma viral loads. However, virus that is integrated in cellular reservoirs can eventually evade these immune responses and replicates at sufficient levels to maintain infection in all infected cats. Therefore, while tests that detect antibody production would normally only denote exposure to a pathogen to which a humoral response is targeted, in the case of FIV, antibody production signals infection because the virus is never cleared. Thus, most of our diagnostic tools depend on the detection of antibodies produced against specific viral antigens. This has become of great concern, because the same antibodies are produced in response to the only commercially available vaccine against FIV, making it difficult to differentiate infection from vaccination in the clinic. New diagnostic approaches are aimed at differentiating vaccination from infection, but little progress has been made clinically available in practice. The majority of cases will be diagnosed through routine testing by veterinarians that follow the guidelines recently proposed by the AAFP. These guidelines suggest all cats should be tested at the time of acquisition, illness, exposure to a cat of unknown status, and routinely in the case of cats with associated lifestyles or those who live in households with infected cats. Following these guidelines will result in the diagnosis of cats that are suffering from clinical signs associated with FIV and many others who are not. It is therefore, important to remember that cats can live with FIV infection for a long time without clinical symptoms if managed appropriately to prevent and treat secondary conditions. It is imperative to follow these guidelines for testing in order to prevent spread of infection my managing the positive cats appropriately and to recognize associated conditions early and offer prompt treatment to immunosuppressed cats. Interpretation of serologic tests can be cofounded by false positives and false negatives, so follow up tests and discriminatory diagnostics should be considered in all cases. Clinical signs associated with late stages of FIV infection include stomatitis, lymphadenopathy, opportunistic infections and lympho-proliferative disease (lymphoma). These cats may require specific therapy aimed at reducing viral loads. In addition to anti-retroviral drugs (discussed above) treatment with human interferon alpha (50 IU on the oral mucosa q 24 hrs, for 7 days, on alternating weeks) has been shown to improve survival in clinically ill cats. The prevalence of FIV in domestic cats is approximately 2% when data from multiple studies is considered. Given that vaccination interferes with diagnosis of infection, it is currently recommended to only vaccinate cats that are at high risk of becoming infected and little is known about the relative efficacy of the vaccine in the population of cats at large. Following the recommended guidelines to continue testing cats routinely and evaluating the effects of antiviral therapies will greatly enhance our understanding of the pathogenesis of FIV and aid in making new therapeutic recommendations in the future. Two comprehensive reviews that detail our clinical recommendations to date have recently been published. These reviews summarize clinically relevant findings in many areas of research and are strongly recommended for veterinarians who diagnose and treat cats in general practice. For a more complete reference list please email [email protected]

REFERENCES

Levy J, Crawford C, Harmann K, Hoffman-Lehmann R, Little S, Sundahl E, and Vicky Thayer. 2008 American Association of Feline Practitioners' feline retrovirus management guidelines. Journal of Feline Medicine and Surgery. 2008: 10 (300-316). Hosie MJ, Addie D, Belak S, et al... Feline Immunodeficiency ABCD guidelines on prevention and management. Journal of Feline Medicine and Surgery. 2009: Jul;11(7):575-84.

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Wednesday, March 3, 2010 Thursday, March 4, 2010 Philadelphia, Pennsylvania

COMPANION ANIMAL: Infectious Diseases

UPDATE AND POTPOURRI OF FELINE INFECTIOUS DISEASES©2010

Alice M. Wolf, DVM, DACVIM, DABVP

Adjunct/Emeritus Professor, College of Veterinary Medicine, Texas A&M University Chief Medical Consultant ­ Veterinary Information Network College Station, TX

BARTONELLOSIS

Introduction Bartonella spp. cause cat scratch disease (CSD) and other clinical syndromes in human beings, and are an important cause of endocarditis in dogs. On the other hand, there is scant documented scientific evidence that Bartonella infection causes overt clinical disease in naturally infected cats, in spite of a high prevalence of bacteremia and seropositivity in areas of the United States with warm temperatures and high humidity. Microbiology Bartonella spp. are facultatively intracellular gram-negative rods that are related closely to Brucella spp and the rickettsiae. Their intra-erythrocytic location precludes easy blood culture and a reliable response to antimicrobial therapy. Four species of Bartonella have been shown to infect pet cats. B. henselae infection is most common, and is the most important cause of CSD. B. clarridgeiae may be responsible for a small number of cases of CSD. Rare infections of cats with B. koehlerae and B. bovis also have been reported. Two main genotypes of Bartonella henselae have been identified worldwide ­ Houston and Marseille. A third genotype, Berlin, has only been identified from one cat in Germany. Exotic cats have also been found to carry Bartonella sp. including: mountain lions, cheetahs, African lions, Florida panthers, pumas, and bobcats. Transmission Bartonella spp. are transmitted between cats by Ctenocephalides felis ­ the cat flea. Fleas ingest the organism during a blood meal from a bacteremic cat, and infect a naïve cat through regurgitation of infected saliva during a subsequent blood meal. Ticks may transmit the organism rarely between cats, and are the primary mode of transmission of Bartonella spp. between dogs. The organisms are not transmitted between cats by fighting, grooming, mating, or in-utero. Human beings become infected with Bartonella spp. when flea feces from a bacteremic cat are inoculated into a cat scratch. Although not confirmed, rarely, infection may possibly be acquired directly through the bite of an infected flea. Cats at Risk Although Bartonella infections in cats have only been reported in the modern veterinary literature since 1992, the organism has apparently been infecting and adapting to cats for hundreds of years. A recent paper reports the isolation of Bartonella antigen from dental pulp by PCR assay in 800 year-old cat teeth from France. The prevalence of bacteremia and seropositivity in cats in the United States is highest in regions that favor the reproduction and persistence of fleas. Rates are highest in the southeastern United States (up to 40%), and lowest in the northern tier of states. The incidence in the EU, UK, and other countries also mirrors this pattern with higher seroprevalence rates in warm, moist locales, and much lower rates in colder climes. Bacteremia is more likely to occur in cats with fleas, free-roaming cats, young cats, and those from multiple-cat populations. Pathogenesis After experimental inoculation into Bartonella-naïve cats, the organisms infect erythrocytes and the initial bacteremia lasts 2 to 32 weeks. After this, infected cats undergo bouts of cyclic bacteremia. Between bacteremic phases, when blood cultures (and blood PCR tests) are negative, the organisms may persist in endothelial cells, lymph nodes, or the central nervous system.

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Following initial production of anti-Bartonella IgM antibody, IgG antibody is produced and remains detectable for months to years. There is no evidence that the height of the IgG antibody titer correlates with the presence of bacteremia ­ this observation is important when considering the diagnostic utility of antibody titers. Clinical Signs ­ Experimental Infections Part of the confusion about the clinical importance of Bartonella infections in cats arises from the observation that clinical signs are more likely to occur in cats after experimental inoculation that in naturally infected cats. Inappropriate extrapolation of data from experimental studies is one of many factors that have led to an overdiagnosis of clinical bartonellosis in the general cat population. Following experimental inoculation, some infected cats have developed an inflammatory lesion at the injection site, mild generalized lymphadenopathy, splenomegaly, fever, lethargy, anorexia, myalgia, behavioral or neurologic changes, and reproductive abnormalities. In a number of other studies, no clinical signs were seen following infection. This probably relates to variable pathogenicity among the strains of B. henselae used in these studies. Clinical Signs ­ Natural Infections With rare exception, Bartonella spp. cause prolonged asymptomatic infections in naturally infected cats. Well-documented clinical signs arising directly from infection are very unusual and mostly anecdotal. Bartonella spp. have been linked directly with endocarditis in one cat. Based on anecdotal reports, the organism may be a rare cause of lymphoplasmacytic gingivostomatitis (LPG) and uveitis. Clinicians should remember that feline calicivirus and plaque intolerance are very common causes of chronic LPG, and that many affected cats coincidentally will be Bartonellaseropositive given the high prevalence of infection with the organism. A similar situation arises with uveitis, which usually is caused by viral or fungal infections. Because uveitis often is accompanied by intra-ocular bleeding, the isolation of Bartonella organisms or antibody from within the eye does not confirm infection. The diagnosis of Bartonella-induced uveitis is supported by the exclusion of all other more common causes, the demonstration of higher antibody levels in the aqueous humor than in serum, and a specific response to selective antimicrobial treatment. Recent studies by Dr. Mike Lappin and the infectious disease group at Colorado State University have shown no statistical differences in Bartonella seropositivity between cats with and without uveitis, oral cavity disease, and central nervous system disease (ACVIM 2005). Bartonella Infections in Human Beings The CDC estimates that there are 24,000 cases of CSD/year in the U.S. This is an incidence of 9.3/10,000 ambulatory patients/year. The seropositivity rate for Bartonella in humans is between 3.6% to 15%; with the latter value occurring in a survey of veterinary professionals. Most persons inoculated accidentally with infected fleas feces through a cat scratch probably show no clinical signs or suffer from a vague, mild self-resolving, flu-like illness that does not prompt a visit to the physician. On the other hand, some immunocompetent people will develop typical CSD, with or without systemic complications. Persons with impaired immune systems are at risk for more severe complications of infection. Typical signs of CSD include the development of a pustule (primary inoculation lesion) in the infected scratch within 7 to 10 days of the injury. Regional lymphadenitis, usually non-painful, occurs within 1 to 3 weeks of the injury. Lymph node enlargement may persist for weeks to months. Antimicrobial treatment does not shorten the duration of disease reliably. Atypical signs of CSD include Parinaud's oculoglandular syndrome (associated with a primary inoculation lesion on the conjunctiva and regional lymphadenopathy following infection of the conjunctiva with flea feces from a bacteremic cat), relapsing bacteremias and fevers, encephalitis, endocarditis, hepatitis, pneumonia, and osteomyelitis. Angioproliferative lesions are more common in immunocompromised persons and include cutaneous lesions of bacillary angiomatosis, and cystic hepatic lesions of bacillary peliosis. Systemic complications of zoonotic Bartonella infections are more likely to be severe in immunocompromised human patients. Paradoxically, the response of these patients to antimicrobial treatment is better than that of immunocompetent patients with typical CSD.

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110TH PENN ANNUAL CONFERENCE - 2010

Wednesday, March 3, 2010 Thursday, March 4, 2010 Philadelphia, Pennsylvania

Diagnosis Laboratory tests to detect or exclude infection with Bartonella spp in cats include the detection of anti-Bartonella antibodies through immunofluorescent antibody (IFA) and Western Blot (WB) tests, blood cultures, and the amplification of Bartonella DNA by polymerase chain reaction (PCR) tests. These tests are used to place cats into one of the following categories: 1. 2. 3. 4. Healthy cats that are not infected with Bartonella spp., and therefore are safe companion animals for immunocompromised persons. Healthy cats that currently are infected with Bartonella spp., or that have been infected previously with Bartonella spp. Sick cats (for example, cats with uveitis or stomatitis) with concurrent Bartonella infection that is not the cause of their clinical illness. Cats with Bartonella-induced illness (an unusual occurrence in clinical practice).

Because of the high prevalence of seropositivity to Bartonella in the general cat population and the low incidence of Bartonella-induced disease, the detection of serum antibodies has a poor predictive value (42 to 46 per cent) for the confirmation of disease caused by the organism. Similarly, using the IFA test, there is a poor correlation between the height of the antibody titer and the ability to detect bacteremia. Because titers in infected cats vary greatly over time, increases in titers associated with vague clinical signs should be interpreted with caution. Conversely, a negative IFA titer has a high negative predictive value (>90 per cent), making it a useful screening test to exclude bacteremia in an asymptomatic or symptomatic cat. A small number of cats may be seronegative between cycles of bacteremia, and blood cultures and PCR tests may be needed to confirm the status of these cats, especially if they are being considered as companion animals for immunocompromised persons. With the possible exception of endocarditis, the clinical diseases attributed anecdotally to infection with Bartonella spp. usually are caused by more common infections. Therefore, tests for these other diseases (for example, FeLV/FIV, toxoplasmosis, cryptococcosis, histoplasmosis, and the aforementioned causes of stomatitis) should be performed and interpreted before tests for Bartonella infection are ordered. Based on our present scientific knowledge of the epidemiology of Bartonella infections in cats and human beings, there are no valid indications for the routine testing and subsequent treatment of healthy pet cats that live with healthy owners. This recommendation is also that of the Centers for Disease Control and this information is available on their website: www.cdc.org Treatment Treatment should be reserved for that small group of sick cats with apparent Bartonella-induced disease, based on careful interpretation of serological and culture/PCR results and an exhaustive exclusion of other more common diseases. At the present time, there is no evidence that antimicrobial therapy eradicates Bartonella organisms completely from infected cats. Although the level of bacteremia may be reduced temporarily, recurrence of bacteremia usually occurs due to the intra-erythrocytic location of the organism. Enrofloxacin and doxycycline have been used to reduce the level of bacteremia. Unfortunately, the recommended dose of enrofloxacin has a high risk of inducing retinotoxicity, precluding its safe use in cats. Azithromycin (5-10 mg/kg PO q24h for 5d, then q48h for 40d) has been recommended for anecdotal cases of stomatitis that were suspected to be caused by Bartonella infection. Unfortunately, because bacteremia is cyclic, and because organisms are rarely cleared with antibiotic therapy, there is no good endpoint on which to base apparent success of treatment. PCR testing may be negative at some point, and then return to positive weeks to months later. Antibodies will persist for years, often at high levels even after organisms are gone. Prevention Prevention of CSD in human beings sharing a house with cats depends primarily on scrupulous and effective flea control. Even if the cat is bacteremic, human infection from cat scratches will not occur unless the injuries are contaminated with flea feces. Children, who are at most risk for the development of CSD if infected, should be taught to play gently with their pet cats, especially new kittens, to avoid scratches.

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Wednesday, March 3, 2010 Thursday, March 4, 2010 Philadelphia, Pennsylvania

Cats being considered as companion animals for immunocompromised persons should be selected from a flea-free background. The cats should be screened initially with an IFA test. If the test is positive, it would be wise to consider the cat no further as a safe companion. If the IFA test is negative, blood cultures and PCR tests should be performed. If these latter tests are negative, the cat can be considered safe, as long as it is kept indoors exclusively, not exposed to cats with fleas, and is treated diligently with a year-round flea-control program.

REFERENCES

1. 2. 3. 4. 5. 6. 7. 8. Pressler B: Bartonellosis. In August JR (ed): Consultations in Feline Internal Medicine, vol 5. St. Louis, Elsevier, 2006, in press. Chomel BB, Boulouis HJ, Breitschwerdt EB: Cat scratch disease and other zoonotic Bartonella infections. J Am Vet Med Assoc 224:1270-1279, 2004. Guptill L: The diagnosis and treatment of Bartonella in dogs and cats. Proc ACVIM Forum, Charlotte NC, 2003. Kumasaka K, et al: Survey of veterinary professionals for antibodies to Bartonella henselae in Japan. Rinsho Byori, 49:906-910, 2001. Rolain JM, et al: Immunofluorescent detection of intraerythrocytic Bartonella henselae in naturally infected cats. J Clin Microbiol 39:2978-2980, 2001 Jacomo V, Kelly PJ, Raoult D: Natural history of Bartonella infections (an exception to Koch's postulate). Clin Diag Lab Immunol 9:8-18, 2002 Yamamoto K, et al: Experimental infection of domestic cats with Bartonella koehlerae and comparison of protein and DNA profiles with those of other Bartonella species infecting cats. J Clin Microbiol 40:466-474, 2002 La VD, et al: Molecular detection of Bartonella henselae DNA in the dental pulp of 800-year-old French cats. Clin Infec Dis 39:1391-1394, 2004.

VIRULENT SYSTEMIC CALICIVIRUS

Signs of this strain of calicivirus may include: High fever Facial and limb edema Ulceration, crusting and focal hair loss, especially on the face, muzzle and pinnae Icterus Dyspnea, DIC and death in severe cases Death may occur in some cats with minimal preceding signs Findings on blood chemistry panel may include hyperbilirubinemia, hyperglucosemia and increased CK. Other signs seen with more typical feline URI may also occur, including nasal and ocular discharge, oral ulceration, anorexia and depression. Unless accompanied by the signs described above, cats showing these typical URI signs should not be considered suspect cases. Course of disease The incubation period is between 1-5 days. Cats of all ages, including fully vaccinated cats, have been affected. No other species is known to be affected by this strain of calici virus. There is no known risk to human health. Treatment, as for any virus, is supportive care. It is likely that a significant percentage of cats will continue to shed virus for some time after recovery from clinical signs, as occurs with other strains of feline calici virus. Therefore cats may still be infectious to others following apparent recovery. Confirmed cases should have negative viral cultures before being reintroduced to other cats. Transmission Virus is present systemically, and may be shed in feces and in nasal, ocular and oral secretions. The virus can be readily spread by fomites as well as direct transmission. It can be carried for at least several hours on contaminated hands, clothing, instruments, shoes, etc. Droplet transmission is possible over 1-2 meters. Although calici virus may be carried through ventilation systems on dust and hair, airborne transmission over distances greater than a few feet has not been documented in this outbreak.

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Wednesday, March 3, 2010 Thursday, March 4, 2010 Philadelphia, Pennsylvania

Prevention Calicivirus is moderately hardy in the environment, but bleach (5% diluted at 1:32) is effective as a disinfectant. Suspect cases should be housed in strict isolation, with separate equipment, gowns, gloves, caps, and protective footwear used. Possibly contaminated surfaces should be thoroughly cleaned with bleach. Contaminated exam rooms should be cleaned with bleach, held empty for 24 hours, and cleaned again with bleach prior to reuse. If contamination of a home or clinic is suspected, all surfaces should be thoroughly cleaned and disinfected. If surfaces can't be bleached, the facility or home should be quarantined for 1-2 weeks following cleaning, prior to allowing entry of naïve cats. Heavily contaminated objects such as bedding should be discarded or thoroughly washed. Veterinary staff and others who handle sick cats should change clothing prior to handling healthy cats and at the end of a shift. There has been no further spread of disease documented in clinics that have taken these precautions. The VS-FCV vaccine is NOT recommended. VS-FCV is NOT a disease of household pets. The virus arises anew in each population in which it appears as a mutation from caliciviruses already carried in that group of cats. There is no single genetic mutation that accounts for virulence. No two strains are alike. The vaccines is adjuvanted and may lead to the development of injection-site sarcoma due to chronic site inflammation. VS FCV suspects in a Private Practice setting from UC Davis Due to increased vigilance nationwide in regards to VS-FCV we are unable to handle to the overwhelming volume of inquiries regarding suspect cases. If you believe that you may have a suspect case please first review our VS-FCV information page http://www.sheltermedicine.com/portal/is_vsfcv.shtml

KEY POINTS TO REMEMBER

1. Neither VS-FCV nor field strain FCV can be diagnosed on clinical signs alone. 2. Diagnosis of calicivirus is further complicated by the fact that calicivirus can be isolated from the oral cavity of as many as 1 in 4 healthy cats, so simply detecting the virus in saliva does not provide a definitive diagnosis - its presence could be completely coincidental. Finding calicivirus in other samples such as serum or tissue is more suggestive that an acute infection is present, but does not rule out the possibility that a co-pathogen such as Bordetella bronchiseptica or panleukopenia is responsible for severe manifestations of disease. 3. So far, no relationship has been discovered between the genetic sequence of a particular strain of calicivirus and the level of virulence. Virulent systemic strains are not particularly closely related to one another, although within each outbreak isolates from individual cats have been similar. Specialized laboratories can only distinguish between strains that are closely related to one another or to the vaccine. Therefore, within a given outbreak it is possible to identify which cats have been infected with that particular strain, but there is no way to say what the virulence may be of any particular strain from an individual cat based on genetic sequence. 4. If you have a single suspect case in your clinic the cat should be carefully isolated and all surfaces should be cleaned with soap and water, followed by application of freshly made bleach solution diluted at 1/2 cup per gallon or potassium peroxymonosulfate (Trifectant®). The area should be allowed to dry thoroughly and the process repeated before any other animals are placed on the surface or in the cage. All suspect cases should be treated symptomatically, the clinic should treat all suspects as being potentially contagious and staff should increase bio-security vigilance. 5. At this point we are unable to provide diagnostic support to facilities reporting a single suspect case. All professional staff who have been in contact with this suspect cat should be advised to protect the health of currently housed cats in the clinic and the health of their personnel pets by thoroughly washing their hand and by changing clothes before coming into contact with subsequent animals. 6. We are interested in receiving tissue samples from suspect cats examined by private practitioners that meet ALL of the following criteria. a. The particular case meeting the criteria as outlined at http://www.sheltermedicine.com/portal/is_vsfcv.shtml AND...

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b. The client reports that other cats in their home have similar symptoms beyond what is generally described as Feline Upper Respiratory Disease and the client has brought these cases into your clinic for examination OR... c. A single case occurred in your clinic AND subsequent to this cats visit, other suspect cases occur in ether animals currently housed in your clinic, or who were in your clinic during the same time as the initial suspect case, or in staff members personnel pets. Or, the individual cat has come from a shelter or rescue group with other suspect cases that have been examined by a veterinarian and have been determined to be suspect VS-FCV cases. 7. VS-FCV has been ruled out in overwhelming majority of VS-FCV cases submitted to our program. In cases VS-FCV has been confirmed, thorough disinfection and strict isolation of suspect cases has been sufficient to end the outbreak. If you suspect a case: Email Dr. Kate Hurley at [email protected] You may also call our program coordinator Mike Bannasch at: 530 7547355.

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110TH PENN ANNUAL CONFERENCE - 2010

Wednesday, March 3, 2010 Thursday, March 4, 2010 Philadelphia, Pennsylvania

COMPANION ANIMAL: Infectious Diseases

CHRONIC DRAINING TRACTS AND NODULES IN CATS®2010

Alice M. Wolf, DVM, DACVIM, DABVP

Adjunct/Emeritus Professor, College of Veterinary Medicine, Texas A&M University Chief Medical Consultant ­ Veterinary Information Network College Station, TX It is very frustrating to be faced with a patient with a "typical cat bite abscess" that fails to respond to repeated attempts at appropriate topical and systemic antibiotic therapy or has recurring problems following an apparent response to therapy. Recurrent or antibiotic resistant nodules and chronic draining tracts or wounds require more intense investigation and thorough reevaluation. Historical investigation should include evaluation for trauma or surgery that may have occurred recently or years in the past. History of travel or previous residence in another locale may suggest exposure to infectious agents not common in the local environment. A thorough physical examination should be performed to determine whether a systemic disorder is present. Common causes of chronic draining wounds in cats include (not necessarily in order of frequency depending on region of the country), foreign bodies (plant awns, teeth, bone sequestra, suture material, porcupine quills), unusual or resistant bacteria (Mycobacteria, Nocardia, Actinomyces, L-forms, Mycoplasma), parasites (Cuterebra), mycotic diseases (Coccidioides, Blastomyces, Histoplasma, Cryptococcus, Sporothrix, Pythium), neoplasms, and congenital defects (dermoid sinus, meningocoele, patent urachus). Diagnostic evaluation of these patients includes a laboratory data base (minimum of CBC, recommend also including a biochemistry profile and urinalysis) and testing for FeLV and FIV infection. Radiographs may be used to identify metallic foreign bodies, tooth fragments, tooth root abscesses, and osteomyelitis. Fistulography with iodinated contrast media (Renografin) can be helpful in determining the depth and direction of some tracts and may outline some radiolucent foreign bodies. Exfoliative cytology of exudate and aspirates from the affected tissue can be used to identify inflammatory cellular constituents and infectious organisms (particularly fungi) in the lesion. Samples for bacteriologic culture (aerobic, anaerobic, and/or fungal) should be collected by deep aspiration or careful deep swabbing of the tract because surface contamination is often present in such lesions and overgrowth of these organisms can mask the true nature of the lesion. Ideally, these procedures are best performed on a fresh, unopened lesion. A portion of the biopsy specimen should also be submitted for culture in a sterile container because some organisms are best cultured from homogenized tissue and will not be recovered from swab specimens alone. Some foreign bodies can be removed by probing the lesion with alligator forceps. Surgical biopsy with special staining (acid fast, and PAS or GMS stains) is required to diagnose some of mycobacterial and fungal diseases. Be sure to request these special stains if you suspect that these infections are present because most laboratories will not routinely perform them. Surgical exploration and extirpation of the lesion is a last step and is often unrewarding unless the true underlying cause of the drainage has been accurately identified. Nocardia often responds well to trimethoprim-sulfadiazine (TMS) given at 30-45 mg/kg PO q12h (2-3 times the usual recommended dose). Long term use of high dose TMS may cause folic acid deficiency anemia and supplementation with folic acid (2 mg/day) may be advisable in these patients. Azithromycin is another drug that may be effective against Nocardia and, because this drug has a long half life in the cat, has the advantage of being able to be administered q48h and q72h dosing for chronic therapy. Recently, we have had several feline patients whose disease failed to respond to the usual therapy and required 6-8 weeks of amikacin injections for resolution. Renal function should be watched carefully during this therapy. Actinomyces should be treated with penicillin or cephalosporins. Bacterial osteomyelitis should be treated for a minimum of 2-3 months with an antibiotic selected on the basis of bacterial culture and sensitivity testing. One of the more interesting causes of chronic abscesses is L-form bacterial infection. L-forms are cell wall-free bacteria that are usually a common species that has undergone alteration due to some environmental pressure. Lesions occur most often on the limbs and systemic signs of illness such as fever and anorexia accompany the abscesses. Joints may be involved and can collapse due to cartilage destruction. This discharge appears purulent and is granulomatous with many PMNs and macrophages. Organisms cannot be identified on cytologic examination and culture on routine bacteriologic media is unsuccessful. L-form infections do not respond to commonly used antibacterial agents but respond promptly to tetracycline drugs (tetracycline and doxycycline [most recommended for the cat due to fewer side effects]). The clinical appearance of Mycoplasma infections is similar to that described for L-forms and tetracycline drugs are also effective against these organisms.

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Atypical Mycobacteria infection is more common in the Pacific northwest but affected cats have been identified from all over the U.S. Draining tracts occur most often in the inguinal area and are frequently associated with proliferative, granulomatous tissue reaction. M. smegmatis, however, has a flatter appearance with new tracts developing from hemorrhagic-appearing spots on the skin. Cytologic examination of the exudate from these lesions demonstrates a mixed population of non-degenerate PMNs and macrophages. Diagnosis is made by identifying organisms on acid fast stains of biopsy specimens. High dose quinolone therapy has been successful in treating these lesions. Clofazamine (Lamprene7) can be used as an alternative. This drug has a long half life and the dosing interval can often be increased to q48h and eventually q72h if healing is occurring as treatment progresses. Clofazamine is not approved for use in the cat and reversibly stains tissues orange-yellow during treatment. Treatment with a combination of clarithromycin and rifampin is another approach that has been successful in some cases. Rifampin should never be used alone because of development of resistance. Potentially useful drugs for the treatment of feline mycobacterial disease: from Dr. Danielle Gunn-Moore Drug Enrofloxacin Rifampicin Clarithromycin Azithromycin Isoniazid Dihydrostreptomycin Pyrazinamide Ethambutol Clofazamine Dose (mg/kg) Interval (hours) 5 PO 10-20 PO 5-10 PO 5-10 PO 10-20 PO 15 IM 15-40 PO 15 PO 8 PO 12-24 12-24 12 12-24 24 24 24 24 24 Toxicity Sudden blindness. Cartilage damage? Hepatotoxicity, discoloration of body fluids. Pinnal or generalised erythema. G-I signs? G-I signs? Hepatotoxicity, peripheral neuritis. Ototoxicity. Hepatotoxicity. Optic neuritis. Hepatotoxicity.

Cryptococcus, Blastomyces, Histoplasma, and Coccidioides are usually responsive to itraconazole (Sporanox7) at 10 mg/kg PO q12-24h or for Cryptococcus, fluconazole 5-10 mg/kg PO q12-24h. Itraconazole and fluconazole cause fewer side effects (anorexia, vomiting, hepatotoxicity) than ketoconazole in the cat. Sporothrix responds to oral iodine therapy (0.5 ml of a 20% solution, PO q24h) and also appears to respond well to itraconazole treatment in some cases (see dose above). Sporotrichosis is a zoonosis and affected cats should be handled carefully. Pythium infections are resistant to all known antifungal agents, surgical removal (if possible) is the treatment of choice. Newer antifungals include voriconazole and caspofungin but little information is available about their use in animals at the present time. Successful management of draining tracts caused by foreign bodies (or parasites) follows identification and removal of the foreign body or sequestrum and includes appropriate selection of an antibacterial agent for systemic therapy to combat secondary invaders. Neoplastic diseases should be properly identified by biopsy and successful treatment depends on the nature of the neoplastic disorder. The age of the cat (young), character of the discharge (usually serous, relatively acellular unless secondary infection is present), and location of the lesion are important clues in identifying congenital anomalies that may be associated with chronic drainage.

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COMPANION ANIMAL: Infectious Diseases

FELINE CHOLANGITIS: UPDATE ON TERMINOLOGY & THE ROLE OF BACTERIA

Mark P. Rondeau, DVM, DACVIM (SAIM)

Staff Veterinarian and Lecturer ­ Matthew J. Ryan Veterinary Hospital University of Pennsylvania, School of Veterinary Medicine Philadelphia, PA

STANDARDIZING THE TERMINOLOGY

Historically, the veterinary literature regarding inflammatory disease of the feline liver and biliary tract has utilized differing and non-standardized classification systems to describe the complex of conditions that may occur1-3. Consequently, it has been difficult to compare results between studies and confusion has developed amongst veterinarians regarding how to describe the condition. A standardized classification system for this disease complex has recently been proposed by the World Small Animal Veterinary Association (WSAVA) Liver Standardization Group.4 This group stratifies cholangitis in cats into the following three categories: neutrophilic cholangitis (NC), lymphocytic cholangitis (LC), and chronic cholangitis associated with liver fluke infestation. NC and LC represent the common inflammatory diseases that have been described previously in the cat. NC is characterized histologically by the presence of neutrophils within the lumen or epithelium of bile ducts. This disease can be seen in acute or chronic stages. During the acute stage, neutrophilic inflammation and edema are often present in portal areas. In chronic NC, mixed inflammation is often present in portal regions, possibly coexistent with bile duct hyperplasia and fibrosis. LC is a disease process characterized histologically by lymphocytic inflammation restricted to portal areas with varying degrees of fibrosis and bile duct hyperplasia. In addition to small lymphocytes, solitary plasma cells and eosinophils may be present.

PREVIOUS TERMINOLOGY

Most classification schemes used previously describe histologic lesions with or without neutrophilic inflammation. For cases with neutrophilic inflammation, previous terminology includes suppurative cholangitis/cholangiohepatitis1,2 or just cholangiohepatitis3. These terms would correlate with what the WSAVA calls NC (including both the acute and chronic forms). The diseases lacking neutrophilic inflammation seem to cause more confusion. This is likely because there are several variants that are not clearly recognized as different entities. A research group at the University of Minnesota described a histologic lesion in which there is predominantly lymphocytic inflammation (+/- plasmacytic) in the portal areas with varying degrees of bile duct hyperplasia and fibrosis as lymphocytic portal hepatitis3. Cats with lymphocytic portal hepatitis lack inflammation associated with the bile ducts, and as such should not be classified as having cholangitis. It has been shown that lymphocytic portal hepatitis is a common lesion in older cats, being present in 82% of cats over 10 years of age and in 96% of cats over 15 years of age in one study5. It is likely that lymphocytic portal hepatitis is a normal finding in aging cats, or that it represents a non-specific response of the liver to disease elsewhere in the body. Cases with lymphocytic inflammation involving the bile ducts has been previously referred to as lymphocytic lymphocytic-plasmacytic cholangitis/cholangiohepatitis1, non-suppurative cholangitis/cholangiohepatitis1, 2 cholangitis/cholangiohepatitis or progressive lymphocytic cholangitis6,7. Within this group of disorders, there seems to be a wide range of varying disease states, which may make the WSAVA classification of LC a bit oversimplified. In some cases there seems to be only inflammation, bile duct hyperplasia and fibrosis. In others, there is destruction and loss of bile ducts, resulting in ductopenia. Other cases may represent a pre-neoplastic state, while some have small cell (low-grade) lymphoma. Whether there is a progression from LC to small cell lymphoma or if these are separate entities has not been clearly elucidated, but much anecdotal evidence suggests that this may be a progression of the same disease. To complicate things further, the disease described as progressive lymphocytic cholangitis in the UK has a very different clinical picture than we typically associate with LC, occurring in younger cats and being marked by icterus and ascites. Better characterization of the lymphocytic inflammatory disorders of the cat is necessary.

PATHOGENESIS OF CHOLANGITIS

A single pathogenesis for cholangitis in cats remains unproven to date. It has been hypothesized that some, perhaps many, cases of cholangitis are associated with ascending bacterial infection from the intestine to the biliary tract, resulting in acute neutrophilic inflammation of bile ducts and ductules1-4. Absent appropriate diagnosis and therapy, the acute

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neutrophilic form of cholangitis may then be followed by the chronic, lymphocytic form of the disease2. Evidence in support of this hypothesis derives from the association reported between cholangitis, pancreatitis, and inflammatory bowel disease8. Despite an obvious association, studies documenting the prevalence of bacterial infection of the biliary tract in affected cats have yielded inconsistent results. Infection rates as low as 14% with NC and 5% with LC have been reported1. However, other studies have documented higher infection rates, including positive bile cultures in 5 of 6 cats with NC in a recent report9. Two studies describing cats with extra-hepatic bile duct obstruction (EHBDO), the majority of which had cholangitis, reported high rates of infection (53% and 55%)10,11. Explanations for negative cultures in some cases may include timing of culture (some patients may have been receiving antibiotics at the time of culture), infection with organisms that are difficult to grow by traditional methods, or inadequate sampling. Evidence of Helicobacter infection has been reported in some cats with cholangitis12,13. A survey of cats with all types of hepatobiliary disease at one institution revealed that positive bacterial cultures were more common when sampling bile (36%, excluding contaminants) than hepatic tissue (14%)14. In addition to the bacterial pathogenesis described above, other theories have suggested an immune-mediated, nutritional or genetic pathogenesis. Evidence for these etiologies is mainly speculative. For example, there is histologic similarity between feline cholangitis and some know immune-mediated diseases in people, namely primary biliary cirrhosis and primary sclerosing cholangitis. Further study into the pathogenesis of feline cholangitis may elucidate the true etiology. However, it is possible that the disease process is multifactorial.

RETROSPECTIVE STUDY

The primary goal of this study was to characterize a population of cats with cholangitis using the classification system developed by the WSAVA Liver Standardization Group, and to determine whether this classification system was applicable to our population of clinically affected cats. The biopsy database at the University of Pennsylvania was searched for cases of feline cholangitis, hepatitis or cholangiohepatitis diagnosed between January 1990 and December 2005. Histopathology was reviewed by a single pathologist and all cases having cholangitis as the primary lesion and a complete medical record were included. Cases were stratified into groups using the WSAVA classification system for feline cholangitis. Cases in which the neutrophil was the predominant inflammatory cell type and in which fibrosis and bile duct hyperplasia were characterized as minimal or mild were classified as acute neutrophilic cholangitis (ANC). Cases with mixed inflammatory cells and a component of neutrophilic inflammation and in which moderate to severe fibrosis or bile duct hyperplasia were present were classified as chronic neutrophilic cholangitis (CNC). Cases in which there was predominantly lymphocytic or lymphoplasmacytic inflammatory infiltrate with minimal to no neutrophilic infiltrate were classified as lymphocytic cholangitis (LC). Seventy-four cases were included in the study. Of these, 13 had ANC, 31 had CNC and 30 had LC. The median age for all cases was 11 years, with no significant difference between groups. 63.5% of cats in the study were male. No breed predilection was found. There were no significant differences between groups in the frequency of any clinical signs or physical examination findings. Cats with CNC were significantly more likely than cats in any other group to have increased ALT, GGT, total bilirubin, total protein, and globulin measurements. However, there was a significant amount of overlap for these values between groups. Ultrasonographic abnormalities associated with the liver were seen frequently in all groups, with no significant differences detected between groups. Ultrasonographic distension of the common bile duct (CBD) was seen more commonly in cats with ANC (42%) and CNC (67%) than in cats with LC (7%). Pancreatic inflammation was common in the few cases that had pancreatic biopsies performed (11/14, 78.5%). Similarly, intestinal inflammation was common in the cases that had intestinal biopsies (16/21, 76.2%). However, there were no differences between groups and the small number of cases that had both intestinal and pancreatic biopsies performed makes interpretation of a relationship between cholangitis, pancreatitis and inflammatory bowel disease difficult. Excluding probable contaminants from analysis, culture yielded bacterial growth in 45% of the cases in which it was performed. Cats with CNC were more likely to have a bacterial pathogen isolated (61.5% of cases) than were cats with LC (21.1%), but there was no difference when cats with CNC and ANC (50%) were compared. Overall, bile cultures were more likely to be positive and less likely to be contaminated than were hepatic cultures. This suggests that bile culture may be preferable to hepatic tissue culture for documentation of bacterial infection in cases of cholangitis. Cats with CNC were more likely to have EHBDO identified at surgery (76%) than were cats with LC (6%), but there was no difference when cats with CNC and ANC (40%) were compared. There was no difference in frequency of bacterial growth in cats with EHBDO compared to those without EHBDO, though cats with CBD distension on ultrasound were more likely to have a pathogen isolated (67%) than those without CBD distension (31%). The overall survival to discharge was 72%, with no differences between groups.

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PROSPECTIVE STUDY

The goals of this ongoing study are to determine the prevalence of bacterial infection in cats with diffuse hepatobiliary disease (including cholangitis), to evaluate the diagnostic utility of hepatic tissue versus bile for the identification of bacterial pathogens in these cats, and to assess the utility of real-time PCR (RT-PCR) for detection of bacterial organisms in frozen hepatic tissue and bile. Cases at the University of Pennsylvania in which hepatic biopsy is performed as part of a complete diagnostic evaluation of diffuse hepatobiliary disease are being enrolled consecutively. Cats receiving antibiotic therapy within 2 days prior to sampling are excluded from the study. For all cases, hepatic tissue is acquired using the method desired by the attending clinician, and bile is collected via cholecystocentesis. Control samples were obtained at the time of euthanasia from cats without liver disease that were part of a breeding colony involved in an unrelated study. Control hepatic tissue was obtained via wedge biopsy and bile via cholecystocentesis within 10 minutes of euthanasia. To date, 22 cases and 8 control cats have been included since April 2006. Aerobic and anaerobic bacterial culture was performed on all samples (hepatic tissue and bile) at the time of acquisition. RT-PCR using 16S rRNA gene primers was performed on batched, frozen samples (hepatic tissue and bile) within 6 months of their acquisition. Routine histopathology using light microscopy was performed on all cases and controls. Cases with cholangitis were categorized as having ANC, CNC or LC as described above. Cases without cholangitis were categorized as having hepatic lipidosis (HL) or other hepatic disease. All histopathology was reviewed by a single pathologist. Twelve cases with cholangitis (7 with CNC and 5 with LC), 5 cats with HL, 5 cats with other types of hepatic disease, and 8 control cats have been evaluated to date. Liver histopathology was normal in all controls. Bile culture was positive in 5 of 22 cases, including 4/7 (57%) cats with CNC, and 1 cat with concurrent HL and biliary carcinoma. The following bacterial organisms were isolated from bile: E.coli (3), -hemolytic Streptococcus (1), P. aeruginosa (1) and an unidentified anaerobic gram-positive rod. RT-PCR of the bile was positive in 4 cases, all of which had positive bile cultures. In 3 of the 4 cases in which RT-PCR was positive, DNA sequencing identified the same organism that had been found using traditional bacterial culture of the bile. In one case, DNA sequencing identified B.fragilis, which had not been identified using bacterial culture. Bile cytology was abnormal in 5/7 cats with CNC, showing either neutrophilic inflammation, presence of bacteria or both. Bile cytology was abnormal in all cats with presence of bacterial infection. Three of the 22 cases had EHBDO identified at surgery and all 3 had evidence of bacterial infection of the bile. Hepatic tissue culture was positive in 2 of 22 cases. In both cases E.coli was isolated from both hepatic tissue and bile of cats with CNC. RT-PCR of hepatic tissue was negative in all cases. Culture and RT-PCR revealed no evidence of bacterial infection in hepatic tissue or bile of any control samples. Due to the small case numbers it is difficult to draw significant conclusions from the data obtained to date from this ongoing study. However, it appears that bacterial infection is more common in cats with CNC than in cats with LC and those with other types of hepatobiliary disease. It also appears that bile may be more useful than hepatic tissue for the purpose of bacterial identification. RT-PCR may be a viable method to rapidly and accurately detect bacterial DNA in bile, but perhaps not in hepatic tissue. All 3 cases with extra-hepatic bile duct obstruction had bacterial infection of bile, further suggesting a strong relationship between these 2 conditions. Further data is required to better define the relationships between cholangitis, extra-hepatic bile duct obstruction and bacterial infection in cats and to determine the optimal diagnostic and therapeutic interventions in these cases.

CONCLUSIONS AND RECOMMENDATIONS

It is obvious that standardized terminology would be useful in eliminating the confusion surrounding the different forms of cholangitis in cats. The WSAVA classification system may not be perfect, but it was easily applied to our clinical population of cats in our retrospective study. This classification system represents a useful starting point for terminology standardization, though it may need to be modified as more information is gathered, especially in regards to the lymphocytic forms of disease. From a clinical standpoint, there is significant overlap in clinical signs, physical exam findings, clinicopathologic findings and imaging findings in cats with all forms of cholangitis. There is also significant overlap between cats with cholangitis and cats with other forms of diffuse hepatobiliary disease, such as hepatic lipidosis and neoplasia. This obviates the need for cytologic and/or histologic samples for diagnosis. Wedge biopsies from multiple liver lobes are preferred, but when these are not available (due to patient or owner restrictions) tru-cut needle biopsies or fine needle aspirate cytology may be useful. Cytology is very sensitive for identifying vacuolar change associated with hepatic lipidosis, but not for identifying underlying causes of lipidosis such as cholangitis or neoplasia. Cytology is specific for identifying lymphoblastic lymphoma,

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but not for other disease processes. Given that many cases of cholangitis are associated with bacterial infection, we recommend obtaining samples for bacterial culture from all cats with diffuse hepatobiliary disease. Based on the results of the above and previous studies, bile obtained via cystocentesis is the recommended sample for aerobic and anaerobic cultures. Once a diagnosis of cholangitis is obtained, treatment is ideally based on results of histopathology and bacterial culture. Cats with ANC and CNC should be suspected of having a bacterial infection. Antibiotic therapy in these cases should ideally be based on culture and sensitivity results and continued for 4-6 weeks (or more if clinical response is not complete). Based on the results of the above and previous studies, empiric antibiotic therapy (either while pending culture results or in the absence of bacterial culture) should include a broad spectrum protocol that is especially effective against gram negative and anaerobic bacteria. Rational choices would include potentiated beta-lactams (such as clavamox) or a combination of a fluoroquinolone (such as marbofloxacin or enrofloxacin) and metronidazole. In cases of ANC or CNC with negative (or lacking) bacterial cultures, we would recommend empiric antibiotic therapy with reevaluation of response (clinical and clinicopathologic) in 1-2 weeks. If the patient is improving, antibiotics should be continued as directed above. However, if there is no response to antibiotics, treatment with immunosuppressive corticosteroids (such as prednisolone 1mg/kg PO BID) would be indicated, as there may be an immune component to these diseases (especially with CNC). In cats with LC, bacterial culture is still recommended, as we have documented bacterial infection in some of those cases. However, most cases are culture negative and many cats with LC will need corticosteroid treatment. The utility of other therapies such as ursodeoxycholic acid, SAMe, milk thistle and vitamin E have not been evaluated for cats with cholangitis. There is a rationale for using ursodeoxycholic acid (10-15 mg/kg PO SID) given its choleretic and immunomodulatory effects. Use of the other drugs listed is clinician dependent, but certainly all have potential benefits without significant negative effects.

1. Center SA, Rowland PH. The cholangitis/cholangiohepatitis complex in the cat, in Proceedings. 12th Annu Meet ACVIM Forum 1994;766-771. 2. Day DG. Feline cholangiohepatitis complex. Vet Clin North Am Small Anim Pract 1995;25:375-385. 3. Gagne JM, Weiss DJ, Armstrong PJ. Histopathologic evaluation of feline inflammatory liver disease. Vet Pathol 1996;33:521-526. 4. van den Ingh TSGAM, Cullen JM, Twedt DC, et al. Morphological classification of biliary disorders of the canine and feline liver. In: Rothuizen J, Bunch SE, Charles JA, et al., eds. WSAVA standards for clinical and histological diagnosis of canine and feline liver disease. Edinburgh: Saunders Elsevier, 2006;61-76. 5. Weiss D, Gagne JM, Armstrong PJ. Characterization of portal lymphocytic infiltrates in feline liver. Vet Clin Path 1995;24:91-95. 6. Lucke VM, Davies JD. Progressive lymphocytic cholangitis in the cat. J Small Anim Pract 1984;25:249-260. 7. Day MJ. Immunohistochemical characterization of the lesions of feline progressive lymphocytic cholangitis/cholangiohepatitis. J Comp Path 1998;119:135-147. 8. Weiss DJ, Gagne JM, Armstrong PJ. Relationship between inflammatory hepatic disease and inflammatory bowel disease, pancreatitis, and nephritis in cats. J Am Vet Med Assoc 1996;209:1114-1116. 9. Brain PH, Barrs VR, Martin P, et al. Feline cholecystitis and acute neutrophilic cholangitis: clinical findings, bacterial isolates and response to treatment in six cases. J Feline Med Surg 2006;8:91-103. 10. Mayhew PD, Holt DE, McLear RC, et al. Pathogenesis and outcome of extrahepatic biliary obstruction in cats. J Small Anim Pract 2002;43:247-253. 11. Eich CS, Ludwig LL. The surgical treatment of cholelithiasis in cats: a study of nine cases. J Am Anim Hosp Assoc 2002;38:290-296. 12. Bookmens SY, Kusters JG, Hoffmann G, et al. Detection of Helicobacter pylori in bile of cats. FEMS Immunol Med Microbiol 2004;42:307-311. 13. Greiter-Wilke A, Scanziani E, Soldati S, et al. Association of Heliobacter with cholangiohepatitis in cats. J Vet Intern Med 2006;20:822-827. 14. Wagner KA, Hartmann FA, Trepanier LA. Bacterial culture results from liver, gallbladder, or bile in 248 dogs and cats evaluated for hepatobiliary disease: 1998-2003. J Vet Intern Med 2007;21:417-424.

REFERENCES

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COMPANION ANIMAL: Vaccinology

CANINE AND FELINE VACCINATION: PROTOCOLS, PRODUCTS, AND PROBLEMS©2010

Alice M. Wolf, DVM, DACVIM, DABVP

Adjunct/Emeritus Professor, College of Veterinary Medicine, Texas A&M University Chief Medical Consultant ­ Veterinary Information Network College Station, TX

GENERAL CONCEPTS:

Dramatic changes have occurred in the past 10 years regarding the way veterinarians view vaccines and vaccination practices. The concepts of core and non-core vaccines, disease risk assessment, extended inter-vaccination intervals, and using products that minimize vaccine-associated inflammation are currently mainstream veterinary medicine. There are now a number of publications that document the long duration of immunity provided by most feline viral vaccines. The third revision of the American Association of Feline Practitioners (AAFP) Vaccination Guidelines for cats was published in late 2006. The second revision of the American Animal Hospital Association Guidelines for vaccination of dogs was published in 2006 and updated in 2007. The World Small Animal Veterinary Association Guidelines were published in 2007. These are very thorough documents that are exhaustively referenced and are an outstanding resource for veterinary practitioners as they change vaccination practices. While a direct association between post-vaccinal chronic inflammation and risk of vaccine-associated sarcoma (VAS) has not been established, adjuvants are known to cause chronic inflammation and have been found histologically in sarcomas. The AAFP Feline Vaccine Advisory Panel suggests that, after considering all available evidence, veterinarians use less inflammatory products whenever possible. The AAFP is careful to state that the direct impact of adjuvants in VAS is currently unclear.

CORE VACCINES FOR CATS:

Core vaccines should be given to every patient regardless of lifestyle. For cats, the core vaccines include: parvovirus (panleukopenia), herpesvirus (feline viral rhinotracheitis), calicivirus and rabies. In the most recent AAFP guidelines, Feline Leukemia (FeLV) vaccine is also recommended as a CORE vaccine for kittens. The reason for recommending universal kitten-hood protection against FeLV is because cats under a year of age are at greatest risk for acquiring this disease. Virtually 100% of kittens infected with FeLV at 6 weeks of age or less will remain persistently infected for life. At 6 months of age, the risk of persistent infection drops to about 30% and this decreases further to 5 15% after 12 months due to the development of natural resistance to this disease with age. When we ask clients about their kitten's environment, they may tell us that the kitten will be kept only indoors. However, the kitten may escape or the client may begin allowing the cat outside. The owner may not return the kitten for FeLV vaccination after the pediatric vaccination series has been completed even though the kitten's risk of exposure to FeLV has changed. By vaccinating the most susceptible individuals (young kittens), we will provide the best possible protection during the period of highest susceptibility to the disease. After a year of age, if the cat truly is kept only indoors without exposure to FeLV-infected cats, we do not need to continue FeLV vaccine administration. I recommend that a non-adjuvanted FeLV vaccine that reduces the potential risks associated with adjuvants be used. FVRCP: Modified live (MLV) FVRCP vaccines are recommended because they are not adjuvanted and do not carry the same risk of inducing chronic vaccine site inflammation as killed adjuvanted vaccines. In addition, a recent study has shown more rapid development of immunity against feline parvovirus in kittens given MLV FVRCP compared to those given killed FVRCP vaccine. RABIES: We have two choices for rabies vaccination of cats. Killed, adjuvanted 3-year licensed vaccines and a recombinant, non-adjuvanted, one year licensed vaccine (PureVax® Rabies - Merial). An important factor in the induction of VAS is chronic inflammation at the injection site. Experimental histologic studies of vaccination sites show that nonadjuvanted vaccines produce little to no inflammation, whereas adjuvanted vaccines cause inflammatory changes at the site that may persist for long periods of time. In my opinion, it is much better to use a non-adjuvanted vaccine more frequently rather than any adjuvanted vaccine, regardless of the frequency of use. An additional advantage of using a rabies vaccine with a one year license is that we can use this to prompt the owner to return for the most important part of

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the yearly visit, the physical examination and wellness assessment.

NON-CORE VACCINES FOR CATS:

FeLV: The FeLV vaccine is considered non-core for adult cats and each patient should have an appropriate lifestyle risk assessment to determine whether this vaccine should be used. Intranasal FVRC or FVRCP: This vaccine has particular use in shelters, catteries, and other situations where early onset of protection is desirable and where exposure to high levels of the URI viruses is expected. While intranasal vaccine with herpesvirus and respiratory calicivirus may be advantageous because this is the natural route of exposure for these agents, this is not the case for feline parvovirus (panleukopenia). The parenteral route is still preferred for this antigen. Chlamydophila and Bordetella are on the AAFP non-core list but I do not recommend giving either of these to household pet cats. Both of these diseases are very uncommon causes of upper respiratory disease and these vaccines are reactive and have a short duration of immunity. Chlamydophila or Bordetella bacterins may be helpful for short-term use in shelter or cattery situations where an outbreak of upper respiratory disease has occurred if these agents are cultured from a number of cats and confirmed as a major component of the respiratory syndrome.

NOT RECOMMENDED VACCINES FOR CATS:

The feline infectious peritonitis (FIP coronavirus) vaccine and feline Giardia vaccines are on the AAFP not recommended list. Neither the WSAVA nor I recommend the currently available FIV vaccine because the vaccine is poorly efficacious, it is adjuvanted, and administration will result in false positive results when cats are tested for FIV. FIV-vaccinated cats will test falsely positive on antibody-based tests (ELISA, Western Blot, IFA) for at least a year post-vaccination. FIV PCR testing is available but some tests are not sufficiently accurate to help us differentiate vaccinated from naturally-infected cats. Virulent Systemic Calicivirus (VS-Calicivirus) is NOT recommended. A review of caliciviral disease follows and explains why this vaccine is neither necessary nor recommended. Calicivirus Etiology ­ Virology Feline calicivirus is a common feline pathogen of the family Caliciviridae. This family of RNA viruses also contains important pathogens of humans and other animals. The replication of caliciviruses is rapid and error-prone. This results in continuous genomic recombination and the production of a genetically diverse group of viruses that adapt quickly to changing environmental and host selection pressures. The genetic variability of feline caliciviruses produces a broad spectrum of pathogenicity and tissue tropism among different viral isolates. This diversity also accounts for the failure of conventional feline calicivirus vaccines to broadly protect cats against the all of the current and constantly emerging new virus variants. Spectrum of Calicivirus-associated disease Acute upper respiratory disease is the most common clinical manifestation of feline calicivirus infection. Physical signs usually include fever, oculonasal discharge, sneezing, and tongue, palate, and/or nasal planum ulceration. Coughing and other signs of lower respiratory involvement or pneumonia may occur occasionally. The management of these cats is supportive and symptomatic and includes maintaining hydration and nutrition, broad-spectrum antibiotic therapy to prevent secondary infections in ulcerated tissues, and pain control. Kittens affected with upper respiratory calicivirus early in life may develop chronic secondary bacterial rhinosinusitis and become "chronic snuffler cats" due to permanent hyperplasia and damage to the nasal turbinates and nasal and sinus mucosa. Arthrotropic calicivirus infection is most often seen in kittens ("limping kitten syndrome"). Signs include fever, lameness, reluctance to walk, and serous polyarthritis with joint effusion. Upper respiratory signs may be absent or may appear after the lameness is apparent. Treatment consists of supportive care with pain management. Most affected kittens improve significantly within 3-5 days. Very rarely, these polyarthritic signs may be seen post-calicivirus vaccination. Virulent systemic calicivirus (VS-FCV) has been widely publicized and this publicity has raised concern in the veterinary community because of several rare clusters of cases that have occurred in veterinary hospitals. Although only recently named as VS-FCV, severe systemic illness and death due to systemic calicivirus is not a new phenomenon and reports in the older veterinary literature describe affected patients similar to those in the current publications. Viral isolates of VS-FCV

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from different clusters of patients are all genetically different. From currently available evidence, it appears that these virulent isolates appear by spontaneous mutation from the cluster of caliciviruses circulating in the particular cat population in which disease occurs. There is no single common genetic mutation or marker that accounts for the pathogenicity of these isolates. Cats affected with VS-FCV initially show signs of typical upper respiratory disease with high fevers, oculonasal discharge, and oral ulceration. The virus then causes vasculitis which produces edema of the ears, face, feet, and/or lower limbs. Tissue necrosis and skin sloughing occurs in the areas of vasculitis and edema. Internal organ involvement may result in pneumonia, pancreatitis, hepatitis, and enteritis. The mortality rate in groups of affected cats may be as high as 30-50%. VS-FCV is primarily a disease of group housed cats with less than ideal husbandry. It is not a disease of household pets. These poorly kept cats maintain a high level of circulating caliciviruses in their population. In addition, the stress on cats in these crowded multiple cat environments probably enhances the replication rate of calicivirus leading to a greater propensity for highly virulent strains to emerge. VS-FCV disease appears suddenly in these populations, affects a small cluster of cats, and then burns itself out and disappears. Although caliciviral shedding in recovered cats may persist for as long as 16 weeks, at the present time, these hypervirulent caliciviruses do not appear to be maintained in the population after the termination of an outbreak and the disease disappears as suddenly as it appeared. Treatment of VS-FCV is symptomatic and supportive. Mortality rates in cluster outbreaks may approach 50% of affected cats. A recent study of a VS-FCV specific, synthetically sequenced, parenterally administered antiviral phosphorodiamidate morpholino oligomer (PMO) shortened recovery time and improved survival in three naturally-occurring outbreaks of severe caliciviral disease. Future work with such compounds may improve our ability to treat and control feline caliciviral infections. Confirming a diagnosis of VS-FCV in the live cat is difficult because serologic testing, PCR examination, virus isolation, and even genetic sequencing cannot differentiate virulent isolates from routine respiratory or arthrotropic caliciviruses. Immunohistochemical identification of calicivirus in vasculitis lesions from biopsies or on necropsy of cats with typical clinical signs is often the most helpful specific diagnostic tool. The Shelter Medicine Program at the University of California at Davis (UCD) performs calicivirus identification and has set out very specific guidelines for submission of samples from suspect VS-FCV patients (Appendix 1). This document also includes a link to the UCD Shelter Medicine website with additional information about virulent calicivirus variants. Prevention: Caliciviruses are highly contagious and transmission is primarily by direct contact with secretions and excretions from infected cats. Outbreaks of respiratory or virulent calicivirus disease are controlled by strict isolation of infected individuals and disinfection of infected premises. Caliciviruses are relatively stable in the environment but can be inactivated with dilute hypochlorite and potassium peroxymonosulfate. Contaminated surfaces should be thoroughly cleaned and disinfected as described in Appendix 1. Veterinary personnel coming in contact with calcivirus affected cats should wash exposed skin thoroughly and change their clothing before handling additional hospitalized cats or returning home to their own pet cats. FCV vaccines only produce non-sterilizing immunity. They are very effective in preventing most cats from developing significant signs of respiratory disease but they do not prevent all signs of illness in all cats. Vaccines do not prevent infection with nor chronic carriage of calcivirus. Because of the rapid evolution of calicivirus mutants and the plethora of calicivirus variants, a recent study reports that currently available monovalent calicivirus vaccine strains protect against only 75-87.5% of street strain isolates. Polyvalent respiratory calicivirus vaccines may be more broadly protective. Conventional respiratory calicivirus vaccines do not protect against VS-FCV. While there is a commercial VS-FCV vaccine presently available, it uses killed virus, it is adjuvanted, and it has only been tested by challenge against the same VS-FCV isolate that is contained in the vaccine. Because each outbreak involves a unique genetic mutant of calicivirus, it is unlikely that a monovalent VS-FCV vaccine will protect against these other highly variable mutant isolates. In addition, VS-FCV is an exceedingly rare manifestation of FCV and it is not a problem in well-kept house pets. I do not recommend the presently available killed virus, adjuvanted VS-FCV vaccine because, in my opinion, the risks of its use outweigh any potential benefit.

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REFERENCES

1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. Abd-Eldaim M, Potgieter L, Kennedy M: Genetic analysis of feline caliciviruses associated with a hemorrhagic-like disease. J Vet Diagn Invest 17(5):420-429, 2005. Bannasch M, Foley J: Epidemiologic evaluation of multiple respiratory pathogens in cats in animal shelters. J Feline Med Surg 7(2):109-119, 2005. Coyne KP, Dawson S, Radford AD, et al: Long-term analysis of feline calicivirus prevalence and viral shedding patterns in naturally-infected colonies of domestic cats. Vet Micriobiol 118(1-2):12-25, 2006. Coyne KP, Jones BRD, Kipar A, et al: Lethal outbreak of disease associated with calicivirus infection in cats. Vet Rec 158(16):544-550, 2006. Coyne KP, Reed FC, Porter CJ, et al: Recombination of feline calicivirus within an endemically infected cat colony. J Gen Virol 87(pt 4):921-926, 2006. Declercq J: Pustular calicivirus dermatitis on the abdomen of two cats following routine ovariectomy. Vet Dermatol 16(6):395-400, 2005. Hurley KE, Pesavento PA, Pedersen NC, et al: An outbreak of virulent systemic calicivirus disease. J Am Vet Med Assoc 224(2):241-249, 2004. Ohe K, Sakai, Sunaga F, et al: Detection of feline calicivirus (FCV) from vaccinated cats and phylogenetic analysis of its capsid genes. Vet Res Commun 30(3):293-305, 2006. Ossiboff R, Sheh A, Shotton J, et al: Feline caliciviruses (FCVs) isolated from cats with virulent systemic disease possess in vitro phenotypes distinct from those of other FVC isolates. J Gen Virol 88(pt 2):506-507, 2007. Porter CJ, Radford AD, Gaskell RM, et al: Comparison of the ability of feline calicivirus (FCV) vaccines to neutralise a panel of current UK FCV isolates. J Feline Med Surg 10(1):32-40, 2008. Poulet H, Brunet S, Leroy V, et al: Immunisation with a combination of two complementary feline calicivirus strains induces a broad cross-protection against heterologus challenges. Vet Microbiol 106(1-2):17-31, 2005. Radford AD, Coyne KP, Dawson S, et al: Feline calicivirus. Vet Res 38(2):318-335, 2007. Radford AD, Dawson, Ryvar R, et al: High genetic diversity of the immunodominant region of the feline calicivirus capid gene in endemically infected cat colonies. Virus Genes 27(2):145-155, 2003. Radford AD, Sommerville LM, Dawson S, et al: Molecular analysis of isolates of feline calicivirus from a population of cats in a rescue shelter. Vet Rec 149(16):477-481, 2001. Radford AD, Dawson S, Coyne KP, et al: The challenge for the next generation of calicivirus vaccines. Vet Microbiol 117:14-18, 2006. Rice CC, Kruger JM, Venta PJ, et al: Genetic characterization of 2 novel feline caliciviruses isolated from cats with idiopathic lower urinary tract disease. J Vet Intern Med 16(3):293-302, 2002. Rong S, Slade D, Floyd-Hawkins K, et al: Characterization of a highly virulent feline calicivirus and attenuation of this virus. Virus Res 122(1-2):95-108, 2006. Smith AW, Iverson PL, O'Hanley PD, et al: Virus-specific antiviral treatment for controlling severe and fatal outbreaks of feline calicivirus infection. Am J Vet Res 69(1):23-32, 2008.

APPENDIX 1: From Dr. Michael Bannasch at the UCD Shelter Medicine Program

VS FCV suspects in a Private Practice setting Due to increased vigilance nationwide in regards to VS-FCV we are unable to handle to the overwhelming volume of inquiries regarding suspect cases. If you believe that you may have a suspect case please first review our VS-FCV information page http://www.sheltermedicine.com/portal/is_vsfcv.shtml Key points to remember 1. Neither VS-FCV nor field strain FCV can be diagnosed on clinical signs alone. 2. Diagnosis of calicivirus is further complicated by the fact that calicivirus can be isolated from the oral cavity of as many as 1 in 4 healthy cats, so simply detecting the virus in saliva does not provide a definitive diagnosis - its presence could be completely coincidental. Finding calicivirus in other samples such as serum or tissue is more suggestive that an acute infection is present, but does not rule out the possibility that a co-pathogen such as Bordetella bronchiseptica or panleukopenia is responsible for severe manifestations of disease.

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3. So far, no relationship has been discovered between the genetic sequence of a particular strain of calicivirus and the level of virulence. Virulent systemic strains are not particularly closely related to one another, although within each outbreak isolates from individual cats have been similar. Specialized laboratories can only distinguish between strains that are closely related to one another or to the vaccine. Therefore, within a given outbreak it is possible to identify which cats have been infected with that particular strain, but there is no way to say what the virulence may be of any particular strain from an individual cat based on genetic sequencing. 4. If you have a single suspect case in your clinic, the cat should be carefully isolated and all surfaces should be cleaned with soap and water, followed by application of freshly made bleach solution diluted at 1/2 cup per gallon or potassium peroxymonosulfate (Trifectant®). The area should be allowed to dry thoroughly and the process repeated before any other animals are placed on the surface or in the cage. All suspect cases should be treated symptomatically, the clinic should treat all suspects as being potentially contagious and staff should increase bio-security vigilance. 5. At this point we are unable to provide diagnostic support to facilities reporting a single suspect case. All professional staff that have been in contact with this suspect cat should be advised to protect the health of currently housed cats in the clinic and the health of their personal pets by thoroughly washing their hands and by changing clothes before coming into contact with subsequent animals. 6. We are interested in receiving tissue samples from suspect cats examined by private practitioners that meet ALL of the following criteria: a. The particular case meets the criteria as outlined at http://www.sheltermedicine.com/portal/is_vsfcv.shtml AND... b. The client reports that other cats in his/her home have similar symptoms beyond what is generally described as Feline Upper Respiratory Disease and the client has brought these cases into your clinic for examination OR... c. A single case occurred in your clinic AND subsequent to this cats visit, other suspect cases occur either in animals currently housed in your clinic, or who were in your clinic during the same time as the initial suspect case, or in staff members personal pets. Or, the individual cat has come from a shelter or rescue group with other suspect cases that have been examined by a veterinarian and have been determined to be suspect VS-FCV cases. 7. VS-FCV has been ruled out in overwhelming majority of VS-FCV cases submitted to our program. In cases VS-FCV has been confirmed, thorough disinfection and strict isolation of suspect cases has been sufficient to end the outbreak.

For additional information, contact: Mike Bannasch Program Coordinator UC Davis Koret Shelter Medicine Program 530-754-7355

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Building the Canine Vaccination Protocol adapted with permission from: Richard B. Ford, DVM, MS

The concept of CORE and NON-CORE vaccines is valid and has direct application in veterinary medicine today. Simply stated, this means separating the vaccines currently in your refrigerator into 2 separate groups: those that every dog and every cat will receive (CORE) and those that the attending clinician decides are necessary (or NOT necessary) based on health risk assessment of the individual patient (NON-CORE). While this may not sound especially important, there is value in assuring that every person in the hospital, technicians as well as veterinarians, is aware of the CORE vaccines and can consistently communicate the same vaccine message to clientele. The series of 4 tables that follow represent a list the CORE vaccines for the dog and current recommendations for incorporating these vaccines into a rational vaccination protocol.

Recommendations for Administration of Canine Vaccines-CORE & Non-CORE CORE Canine Vaccines and Recommendations for Administration

(based on the 2006 Report of the AAHA Canine Vaccine Task Force) CORE Vaccines Distemper Recombinant, or Modified-Live Parvovirus Modified-Live Adenovirus-2 Modified-Live (SQ injection) Rabies Killed-1 Year Killed-3-Year (SQ injection) Primary Puppy Series (< 16 weeks) Primary Adult Series (> 16 weeks)

Booster Interval

Administer 1 dose at 6-8 weeks of age, then, Every 3 to 4 weeks until 15-16 weeks of age.

Administer 2 doses 3 to 4 weeks apart.

Administer 1 dose one year following completion of the initial series; then Every 3 years thereafter.

Administer 1 dose at 12 to 16 weeks of age.

Administer 1 dose

Administer 1 dose one year following administration of the first dose, then annually or triennially according to product label.

NOTE: Requirements for canine rabies vaccination are established by State and/or local statutes and may differ from the recommendations listed above.

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NON-CORE Canine Vaccines and Recommendations for Administration

(based on the Report of the 2006 AAHA Canine Vaccine Task Force) NON-CORE (optional) Vaccines Bordetella bronchiseptica + Parainfluenza Avirulent-Live Primary Puppy Series (< 16 weeks) A single dose is recommended by the manufacturers and some may be given as early as 3-4 weeks of age. Check product literature for specific age recommendations. 2 doses, 2 to 4 weeks apart are recommended. Primary Adult Series (> 16 weeks) A single dose.

Booster Interval Annually; animals in a high risk/exposure environment may benefit from a booster if longer than 6 months since the previous dose.

(intranasal administration ONLY) Bordetella bronchiseptica Killed, or Antigen Extract (SQ administration) Leptospirosis (serovars: canicola, icterohemmorhagiae, pomona, grippotyphosa) Various 2-way and 4-way combinations are available. Killed bacterin (SQ administration) Lyme borreliosis Recombinant, or Killed bacterin

Administer 2 doses, 2 to 4 weeks apart beginning as early as 8 weeks of age. Administer 2 doses, 2 to 4 weeks apart beginning as early as 12 weeks of age. (Vaccination of dogs less than 12 weeks of age is generally not recommended)

Administer 2 doses, 2 to 4 weeks apart.

Administer 2 doses, 2 to 4 weeks apart.

Annually; animals in a high risk/exposure environment may benefit from a booster if longer than 6 months since the previous dose. Annual booster is recommended for dogs with a defined risk of exposure. Vaccination is not recommended for all dogs. Exposure risk should be considered prior to recommending.

Administer 2 doses, 2 to 4 weeks apart beginning as early as 9 weeks of age.

Administer 2 doses, 2 to 4 weeks apart.

Annual booster is recommended for dogs with a defined risk of exposure. Vaccination is not recommended for all dogs.

Recommendations vary Recommendations vary Not Stipulated. depending on size of the depending on size of the dog and risk of dog and risk of Duration of immunity studies exposure. See exposure. See have not been conducted. Manufacturer's Manufacturer's (SQ administration) Recommendations. Recommendations. Porpyhromonas spp. Administer 2 doses, 3 Administer 2 doses, 3 Not Stipulated. (prevention of weeks apart beginning weeks apart. periodontitis) as early as 7 weeks of Duration of immunity studies Killed bacterin age (manufacturer have not been conducted. (SQ administration) recommendation) NOTE: Although vaccines licensed by the USDA are currently available in the United States, routine vaccination of dogs against coronavirus and Giardia lamblia is NOT recommended.

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(SQ administration) Crotalus atrox (Western Diamondback Rattlesnake vaccine) Toxoid

110TH PENN ANNUAL CONFERENCE - 2010

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CANINE INFLUENZA VACCINE: Canine influenza is an uncommon disease seen primarily in group-housed dogs with poor husbandry. It is not a common disease among household pets. A killed virus vaccine against canine influenza was released in mid-2009. The AAHA has not yet updated their guidelines to include this new product. This canine influenza vaccine is conditionally licensed and it requires 2 doses to provide protection. Therefore, protective immunity will not be established until 3-4 weeks following the initial vaccine administration. This canine influenza vaccine produces non-sterilizing immunity and it is reported to lessen (but not prevent) clinical signs, reduce the duration of signs, and vaccination does not prevent infection or shedding of the virus. At the present time, the canine influenza vaccine is considered to be non-core and it is recommended primarily for dogs with a significant potential for exposure such as racing greyhounds and show dogs. It may also be recommended in locales where an outbreak of the disease is occurring. PEDIATRIC VACCINATION: The goal of pediatric vaccination is to stimulate active and solid immunity before the susceptible kitten or puppy is exposed to pathogenic organisms. This means that we must start a vaccination program early enough to prevent active disease as maternal antibody wanes. The pediatric core FVRCP vaccine series should be started when the kitten or puppy is seen for its first pediatric examination at 6-8 weeks of age. Core vaccines should be repeated at 3-4 week intervals until the kitten or puppy is 16 weeks of age. Although some biologics manufacturers have experimental studies that demonstrate good protection by 12 weeks of age, recent research using conventional kittens indicates that maternal antibody interference with vaccination may persist in some kittens beyond 14 weeks of age. Therefore, I recommend administering the final pediatric vaccination at 16 weeks of age or older. Rabies vaccine should be given at 12 weeks of age or older as per the Rabies Compendium and state/local ordinances. I recommend using only a non-adjuvanted rabies vaccine for cats and a 3-year licensed rabies vaccine for dogs. Kittens should be tested negative for FeLV prior to vaccination. In addition to the other serious consequences of infection, there is no demonstrated benefit of giving an FeLV vaccine to an FeLV-infected cat. I recommend using a non-adjuvanted FeLV vaccine according to the manufacturer's instructions. RE-VACCINATION INTERVALS: The CORE vaccines: FVRCP, FeLV, DAP, and RV should be repeated at one year of age. As per AAHA, AAFP and ACVIM recommendations, FVRCP or DAP is given no more frequently than every 3 years after that time. RV should be readministered according to the manufacturer's licensing approval (1 year or 3 years) and according to state/local ordinance. FeLV vaccination may be continued according to manufacturer's instructions if the cat is at risk of exposure after 1 year of age. Non-CORE vaccines (e.g. Leptospirosis, Bordetella, Borrelia) are primarily bacterins and have a shorter duration of immunity than viral vaccines. These vaccines will need to be repeated yearly in order to maintain an effective level of immunity.

VACCINE SAFETY: ADVERSE EVENTS AND HOW TO AVOID THEM

INTRODUCTION Adverse events associated with vaccine administration to small animals are relatively rare given the frequency with which vaccines are given to patients and the complexity of these biological agents. Two recently published studies reviewed patient records from the database of a large corporate veterinary clinic network. The incidence of adverse events associated with vaccination was reported to approximately 1:250 for dogs within 3 days of vaccination and 1:200 for cats within 30 days of vaccination. In these studies, young animals and small breeds of dogs receiving multiple vaccines/antigens per visit were at higher risk for an adverse event. Unfortunately, the true incidence of adverse events associated with vaccination is still largely unknown because adverse events may not be recognized as vaccine-related, may not be reported by owners to veterinarians, may not be reported by veterinarians to manufacturers, and because we have no unbiased national database for adverse event reporting to which veterinarians or researchers have access.

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DIRECT EFFECTS OF VACCINES Activation of the immune system by vaccination Stimulation of the immune system by parenteral vaccination may cause malaise, fever, inappetence, and lymphadenopathy due to the activation of immunologic and inflammatory pathways with resultant increases in lymphokines, interferons, leukotrienes, and other inflammatory mediators. Such reactivity usually appears within 24-48 hours of vaccination and is generally mild, transient, and self-limited. This is the most common post-vaccinal adverse event in cats. The effects of such immune stimulation may be blunted by pre- and post-treatment with non-steroidal anti-inflammatory drugs. In adult dogs, administering no more than one vaccine per visit and separating individual vaccine adminstration by 3-4 weeks may also help to reduce this adverse event. Immunosuppression caused by vaccines Transient immunosuppression associated with vaccination can be demonstrated with modified live virus (MLV) antigens. MLV distemper immunosuppression may be a factor in the hypertrophic osteodystrophy-like syndrome seen in young Weimaraner dogs that are affected with a breed-related neutrophil function defect. For this reason, recombinant Distemper antigen is recommended for this breed. Rarely, post-vaccinal immunosuppression may allow subclinical opportunistic infections to become clinically apparent. Often there is no way to predict these events and no way to effectively prevent the potential consequences of immunosuppression. Vaccine administration should be avoided in animals receiving cyclosporine and other potent immunosuppressive drugs, and those with known immunodeficiency syndromes. Local site reactions Local site reactions include an immediate pain response on injection, transient swelling and pain at the injection site, and inflammatory nodules that may persist for weeks to months following vaccination. In the review study of adverse events in cats, the most common adverse event at 30 days post-vaccination was a palpable nodule remaining at the injection site. It is this chronic vaccination site inflammation that is widely believed to be the underlying cause for the development of vaccine-associated sarcomas (VAS) in cats. Avoiding vaccines that contain inflammatory ingredients such as vaccine adjuvant should decrease the incidence of local site reactions. HYPERSENSITIVITY REACTIONS Type I Hypersensitivity Type I hypersensitivity reactions mediated by IgE and encompass a wide range of acute clinical presentations. These reactions range from minor urticaria/angioedema to dramatic and potentially fatal anaphylaxis. Cats rarely develop urticaria but anaphylaxis is fairly common. The liver is the primary shock organ for the dog and the lung is the primary shock organ in cats. Both species may exhibit collapse, cyanosis, vomiting, diarrhea, or dyspnea associated with an anaphylactic reaction. We tend to think narrowly about the constituents in our vaccine products. In addition to the desirable antigen(s), there are a number of residual proteins and other potential sensitizing compounds that may remain from the vaccine manufacturing process or that may be added as part of that process. These sensitizers may be present in minute amounts but this may be sufficient to stimulate and then trigger the hypersensitivity response upon subsequent vaccine exposure. Sensitizers include bovine serum albumin and fibronectin from fetal calf serum used in viral culture media, antibiotics used during viral culture to prevent bacterial overgrowth, and casein, gelatin, and other stabilizers used to extend vaccine shelf life. Rarely, type I reactions may occur with the first vaccine administration. It is believed that maternal transfer of antigen-specific IgE that binds to mast cells in the offspring accounts for these unusual and unexpected reactions. While not supported by controlled studies, clinical experience suggests that urticaria/angioedema is often associated with the administration of Leptospira antigen in dogs, however, this reaction can occur as a response to any vaccine. The Dachshund breed appears to be more frequently affected by post-vaccinal urticaria/angioedema. The Pug breed appears to have a predisposition to post-vaccinal anaphylaxis. If the offending sensitizer can be recognized, it should be avoided in the future. If additional vaccine must be given in the future, pre-treatment with diphenhydramine 2.2 mg/kg IM and rapid acting glucocorticosteroid 30 minutes prior to vaccination may prevent the urticarial/angioedema response. The patient should be hospitalized and observed for the day.

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If anaphylaxis has occurred, the best approach is to completely avoid future administration of the offending vaccine to that patient. Type II Hypersensitivity Type II hypersensitivity is an immune-complex reaction associated with IgM and/or IgG antibody and mediated through activation of the classical complement cascade leading to direct cell membrane attack and lysis. Rarely, type II hypersensitivity may involve cell-mediated cytotoxicity. Hematologic disorders (immune-mediated hemolytic anemia [IMHA] and immune-mediated thrombocytopenia [IMTP]) are the most common types of type II hypersensitivity reactions attributed to small animal vaccination. If these disorders are vaccine-related, clinical signs usually appear within 3 weeks of vaccination. Other type II immune-complex disorders reported in association with vaccination include polyarthritis and polyneuritis. The pathophysiology behind these apparently vaccine-related immune complex events is unclear. Suggested mechanisms for this reactivity include: alterations of immunoregulation by vaccination, non-specific immune activation by adjuvants or microbe-derived "superantigens", and molecular mimicry between autoantigens and vaccine antigens. Exposure to crossreactive tissue protein in vaccine is another proposed mechanism of vaccine injury that has recently been investigated in cats. Preliminary experimental studies show that residual proteins from virus culture on Crandall-Rees feline kidney cells remain in sufficient quantities in some feline parenteral vaccines to generate auto-antibody against normal feline kidney cells. What is not yet known is whether these cross reacting antibodies are of any clinical relevance to the cat. However, I believe that it is yet another excellent reason to avoid overvaccination of cats. Revaccination should be avoided in the future in patients with vaccine-related type II hypersensitivity diseases. Type III Hypersensitivity Type III hypersensitivity results in large immune complexes that are deposited in the walls of blood vessels leading to immunologic attack and vasculitis. These reactions are very slow to develop and clinical signs may not appear for several weeks following vaccination. The classic type III hypersensitivity reaction is the Arthus vasculitis associated with canine adenovirus 1 antigen that causes the "blue eye" (corneal edema) reaction in dogs. The most common type III vaccine-related event is post-vaccinal cutaneous vasculopathy. This event is almost always associated with subcutaneous rabies vaccine administration. Histopathologic examination demonstrates an ischemic dermatopathy associated with vasculitis and panniculitis. Rabies antigen and complement can be demonstrated within vascular walls with immunohistochemical staining. Cutaneous vasculopathy may occur in any dog but appears most frequently in soft-coated dogs such as Poodles and Terriers that have hair that grows continuously. The cutaneous vasculopathy lesions consist of well-demarcated, often hyperpigmented areas of hair loss occurring at the vaccination site. Because it may take some time for the hair to epilate from the site, there may be a lag time of weeks to months after vaccination before cutaneous vasculopathy lesions become apparent. If recognized early, it may be possible to stimulate hair regrowth by treating with pentoxyfylline at 25 mg/kg PO q12h and Vitamin E. Surgery may also be performed to remove the area of vasculitis-related alopecia. This problem can be prevented by avoiding the vaccine that induced the lesion. Systemic vasculopathy/vasculitis is a rare but much more severe type III reaction. Because systemic vasculitis is a more recently recognized problem, there are few descriptions of this problem in the veterinary literature at the present time. Dachshunds, Chihuahuas, Whippets, and Italian greyhounds tend to manifest vasculitis as ear tip thrombosis and necrosis. Some dogs may develop blistering or ulcerative lesions at mucocutaneous junctions or areas at the conjunction of haired and non-haired skin. Oral mucous membrane and tongue ulceration, toenail and digital necrosis, footpad sloughing, and other skin lesions have also been observed. Systemic vasculitis lesions usually appear within 2-3 weeks of vaccination. Diagnosis of systemic vasculitis/vasculopathy is made by biopsy of lesions to confirm the vasculitis. Systemic vasculitis may be a life-threatening event. Treatment includes pentoxifylline and vitamin E as previously described for cutaneous vasculopathy. Additional therapy may include fluid, electrolyte, and nutritional support. Corticosteroids, antibiotics, gastric protectants, and analgesics may be used depending on the severity and location of the lesions.

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Complete healing may take many weeks. Systemic vasculitis reactions are serious and should be considered potentially lifethreatening. Prevention consists of avoiding any revaccination of the patient in the future. Revaccination should be avoided in patients with Type III hypersensitivity reactions. VACCINE-ASSOCIATED SARCOMA Vaccine-associated sarcomas (VAS) are connective tissue tumors occurring at vaccination sites in response to chronic vaccine-induced inflammation. These neoplasms are highly malignant and very locally invasive. While the cat is definitely at highest risk for developing post-vaccinal sarcoma, vaccine site sarcomas have also been reported in dogs and in ferrets. This serious and often fatal adverse vaccine event was first described in 1991 and concern about this problem led to the formation of several panels and a national task force to study it further. In response to the recognition of VAS, the American Association of Feline Practitioners issued recommendations for decreased frequency of vaccine administration, use of less reactive feline vaccines, and specific sites for vaccine administration in cats. Recently, a genetic marker has been identified that may be the underlying factor predisposing some cats to neoplastic transformation at the site of chronic vaccine-induced inflammation. The incidence of VAS has been variably reported in the literature as between 1.3 per 1000 to 1 per 10,000 cats. Older cats (mean age 8-9 years) are more frequently affected and VAS has been seen in cats not vaccinated for 5-9 years suggesting that it may take many years for neoplastic development to become apparent. VAS has been difficult to study because tumors may take years to develop, veterinarians change the vaccine products they use, vaccination records may be incomplete, and the patient population is highly mobile. The one published retrospective review of VAS incidence is limited by the small number of animals used, the assumption that whatever vaccine was used the year the tumor developed was the initiating cause, and because non-adjuvanted recombinant vaccines had not been available long enough to be evaluated in the data analysis. Because VAS incidence is low, statistically valid prospective experimental studies would require too many animals to be practical or ethical. Therefore, the exact etiopathogenesis and underlying mechanism for VAS development remains a controversial issue. Nevertheless, vaccine adjvant is believed by many veterinarians to play a significant role in the post-vaccinal inflammation that leads to VAS development. This contention is supported by the temporal association between the appearance of VAS and the introduction of killed, adjuvanted rabies vaccines, killed adjuvanted feline leukemia vaccines, and killed adjuvanted FVRCP vaccine. The United Kingdom (UK) Veterinary Medicines Directorate has had an adverse event monitoring system in place since 1984. A report of data analysis from this program demonstrated an increasing incidence of VAS from 1995 to 1999 with sarcomas occurring more frequently in cats receiving FeLV vaccine (adjuvanted) or other killed feline vaccines containing aluminum adjuvants. Rabies vaccines are not used in the UK. A recent review of VAS incidence and changes in site locations of VAS from 1990 to 2006 demonstrates an increasing incidence of neoplasms and a shift in their location from the interscapular area to the hind limbs. This geographic shift in location corresponds to changes in vaccination protocols to administer rabies and feline leukemia vaccines in the hind limbs of the cat recommended by the AAFP in 1996. In 1999, the World Health Organization classified veterinary vaccine adjuvant as a class III/IV carcinogen on the basis of their review of the literature on VAS. All post-vaccinal masses persisting for more than 4 weeks should be biopsied. Inflammatory masses should be completely excised with wide margins. If histopathologic examination confirms neoplasia, the patient should be referred for definitive and radical treatment. Because VAS have tendrils of neoplastic cells that extend deeply from the primary lesion, effective treatment requires detailed imaging (CT or MRI) to define the exact extent of the neoplastic tissue, complete surgical excision with deep margins, and follow up radiation and/or chemotherapy. Prevention of VAS involves avoiding inflammatory vaccines that can potentially induce neoplastic transformation in genetically predisposed cats. Using the AAFP recommended vaccination sites will facilitate complete excision of a VAS should one occur. PRODUCT-RELATED EVENTS The major biologics manufacturers have highly controlled production processes and quality control systems to assure the efficacy and safety of their products and direct product-related adverse events are very rare. Some examples of productrelated events include residual virulence of modified live virus vaccines or attenuated bacterins, interaction between viral vaccine components, contamination of canine vaccine with bluetongue virus, and rabies vaccine recall due to failure of efficacy in a longer duration of immunity study. Unfortunately, there is no way to predict or prevent product-related events. However, if such an event is suspected, it should be reported to the manufacturer immediately.

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LACK OF IMMUNOLOGIC RESPONSE TO VACCINES AS AN ADVERSE EVENT Most situations where vaccines fail to produce protective immunity are not related poor product efficacy but most often to improper vaccine handling or administration, or the inability of the host immune system to mount an adequate immunologic response to the vaccine. Vaccines subjected to temperature variations or extremes during shipping and storage may lose potency. The administration of vaccines to ill or immunosuppressed patients may at best be ineffective and rarely may cause disease. MLV intranasal upper respiratory vaccines should not be administered to cats with retroviral infection (FeLV or FIV) because they can induce severe upper respiratory signs including oculonasal discharge and nasal or oral ulceration. Animals that lack a certain lymphocyte subset or subsets that are critical for recognition and generation of a protective response to a particular antigen are called non-responders or sub-optimal responders. These animals can be vaccinated repeatedly with highly efficacious vaccines but fail to be protected because they lack the genetic programming to respond. Some breeds of dog (Rottweiler, Doberman, Pit Bull) appear to be more susceptible to canine parvovirus and may develop disease in spite of having received one or more vaccines. It is likely that these animals represent non-responders. We see fewer of these individuals now than in the past because we have more efficacious canine parvovirus vaccines and because many non-responders that developed clinical parvovirus disease died as a result and are no longer contributing to the gene pool. ANTIBODY PRODUCTION AS AN ADVERSE EVENT In addition to the immune-mediated disease previously mentioned, there are other examples where the immunologic response to vaccination may have a negative effect. In an experimental study, cats vaccinated with intranasal feline coronavirus vaccine (FIP vaccine) developed antibodies that caused antibody dependent enhancement of disease when they were challenged with a pathogenic coronavirus. More vaccinated cats died and they died more rapidly than unvaccinated cats in this study. Vaccination with the feline immunodeficiency virus vaccine generates antibody that is indistinguishable from natural infection. FIV-vaccinated cats will test positive with both ELISA and Western blot diagnostic tests for FIV for at least a year post-vaccination confounding our ability to determine whether they have true infection or not. ADVERSE EVENT REPORTING In order to properly report a suspected adverse vaccine event, veterinarians must keep accurate patient records that include the product name, manufacturer, lot and serial number, and the location of vaccine administration. All suspected events should be reported immediately to the professional services hotline for the vaccine manufacturer. If the patient is given several vaccines produced by different manufacturers, it will be impossible to determine which one may have caused the adverse event. If an adverse event is confirmed, it should also be reported to the USDA adverse event reporting site: http://www.aphis.usda.gov/animal_health/vet_biologics/vb_adverse_event.shtml

REFERENCES

Alberdein D, Munday JS, Dyer CB, Knight CG, French AF, Gibson IR: Comparison of the histology and immunohistochemistry of vaccination-site and non-vaccination-site sarcomas from cats in New Zealand. N Z Vet J. 2007 Oct;55(5):203-7 Banerji N, Kapur V, Kanjilal S: Association of germ-line polymorphisms in the feline p53 gene with genetic predisposition to vaccine-associated feline sarcoma. J Hered 2007;98(5):421-7. Burton G, Mason KV : Do postvaccinal sarcomas occur in Australian cats? Aust Vet J. 1997 Feb;75(2):102-6 Day MJ et al, A kinetic study of histopathological changes in the subcutis of cats injected with non-adjuvanted and adjuvanted multi-component vaccines. 2007 May 16;25(20):4073-84 Day MJ, Horzinek MC, Schultz RD: WSAVA Guidelines for Vaccination. J Sm Anim Pract 2007;48(9):528-541 Day MJ: Does inflammation trigger cancer in cats? Proceedings World Small Animal Veterinary Congress 2007. Day MJ: Vaccine side effects: Fact and fiction. Vet Micriobiol 2006 117:51-58.

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Deim Z, Palmai N, Cserni G. Feline vaccine-associated fibrosarcoma induced by aluminium compound in two cats: short communication. Acta Vet Hung. 2008 Mar;56(1):111-6. De Man MM, Ducatelle RV: Bilateral subcutaneous fibrosarcomas in a cat following feline parvo-, herpes- and calicivirus vaccination. J Feline Med Surg. 2007 Oct;9(5):432-4. Duval D, Giger U: Vaccine-associated immune-mediated hemolytic anemia in the dog. J Vet Intern Med 1996 10:290-295. Foley JE, et al: Outbreak of fatal salmonellosis in cast folliwng use of a high-titer modified-live panleukopenia vaccine. J Am Anim Hosp Assoc 1999 214:67-70. Hendrick MJ, Goldschmidt MH: Do injection site reactions induce fibrosarcomas in cats? J Am Vet Med Assoc. 1991 Oct 15;199(8):968. Horzinek MC, Thiry E: Vaccines and vaccination: the principles and the polemics. J Feline Med Surg. July 2009;11(7):530-7. Jelínek F. Postinflammatory sarcoma in cats. Exp Toxicol Pathol. 2003 Sep;55(2-3):167-72. Lester S, Clemett T, Burt A: Vaccine site-associated sarcomas in cats: clinical experience and a laboratory review (19821993). J Am Anim Hosp Assoc. 1996 Mar-Apr;32(2):91-5. Kass P, et al: Multicenter case-control study of risk factors associated with development of vaccine-associated sarcomas in cats. J Am Vet Med Assoc. November 2003;223(9):1283-92. Kohn SL et al: Polyarthritis following vaccination in 4 dogs. Vet Comp Orthopaed Traumatol 2003 16:6-10. Lappin MR, et al: Investigation of the induction of antibodies against Crandall-Ress feline kidney cell lysates and feline renal cell lysates after parenteral administration of vaccines against feline viral rhinotracheitis, calicivirus and panleukopenia in cats. Am J Vet Res 2005 66: 506-511. Levy JK, Crawford PC, Slater MR: Effect of vaccination against feline immunodeficiency virus on results of serologic testing in cats. J Am Vet Med Assoc 2004 225:1558-1561. McAnulty JF, Rudd RG: Thrombocytopenia associated with vaccination of a dog with modified-live paramyxovirus vaccine. J Am Vet Med Assoc 1985 186:1217-1219. McEntee MC, Page RL: Feline vaccine-associated sarcomas. J Vet Intern Med 2001 15:176-182. Moore GE et al: Adverse events after vaccine administration in cats: 2,560 cases (2002-2005) Am Vet Med Assoc. July 2007;231(1):94-100. Moore GE et al: Adverse events diagnosed within three days of vaccine administration in dogs. J Am Vet Med Assoc. October 2005;227(7):1102-8. Munday JS, Stedman NL, Richey JS: Histology and immunohistochemistry of seven ferret vaccination-site fibrosarcomas. Vet Pathol. May 2003;40(3):288-93. O'Toole D, Van Campen H, Woodard L: Bluetongue virus: contamination of vaccine. J Am Vet Med Assoc. August 1994;205(3):407-8. Ohmori K et al: IgE reactivity to vaccine components in dogs that developed immediate-type allergic reactions after vaccination. Vet Immunol Immunopathol 2005 104:249-256.

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Rassnick KM: Feline vaccine-associated sarcomas: The problem is not over yet. Proceedings ACVIM Forum 2006. Richards JR et al: The 2006 American Association of Feline Practitioners Feline Vaccine Advisory Panel report. J Am Vet Med Assoc. November 2006;229(9):1405-41. Roth JA: Mechanistic bases for adverse vaccine reactions and vaccine failures. Adv Vet Med 1999 41:681-700. Scott FW, Corapi WV, Olsen CW: Evaluation of the safety and efficacy of Primucell- FIP Vaccine. Feline Health Topics. September 1992;7(3):6-8. Shaw SC, Kent MS, Gordon IK, et al. Temporal changes in characteristics of injection-site sarcomas in cats: 392 cases. (1990-2006). J Am Vet Med Assoc. 2009 Feb 1;234(3):376-80. Spickler AR, Roth JA: Adjuvants in veterinary vaccines: Modes of action and adverse events. J Vet Intern Med. 2003 May-Jun;17(3):273-81. Strasser A et al: Immune modulation following immunization with polyvalent vaccines in dogs. Vet Immunol Immunopathol 2003 94:113-121. Vaccine-Associated Feline Sarcoma Task Force: The current understanding and management of vaccine-associated sarcomas in cats. J Am Vet Med Assoc. June 2005;226(11):1821-42. Vascellari M et al: Fibrosarcomas at presumed sites of injection in dogs: characteristics and comparison with nonvaccination site fibrosarcomas and feline post-vaccinal fibrosarcomas. J Vet Med A Physiol Pathol Clin Med. August 2003;50(6):286-91. Vitale CB, Gross TL, Magro CM: Vaccine-induced ischemic dermatopathy in the dog. Vet Dermatol 1999 10:131-142. Whittemore JC et al: Feline serum antibody responses to Crandall-Rees feline kidney cell inoculations and characterization of target antigens. J Vet Intern Med 2005 19-449Wilson RB, Holladay JA, Cave JS: A Neurologic Syndrome Associated with Use of a Canine Coronavirus-Parvovirus Vaccine in a Dog. Compend Contin Educ Pract Vet. February 1986; 8(2):117-124. World Health Organization: International Agency for Research on Cancer IARC Monographs on the Evaluation of Carcinogenic Risks to Humans Volume 74; 23 February - 2 March, 1999, PP: 24, 305, 310 UC Davis Koret Shelter Medicine Program 530-754-7355

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COMPANION ANIMAL: Vaccinology

EFFECTIVE CANCER VACCINES ­ A PROMISE OR PIPE-DREAM?

Nicola Mason, BVM, PhD, DACVIM

Assistant Professor, Medicine & Pathobiology University of Pennsylvania, School of Veterinary Medicine Philadelphia, PA

INTRODUCTION

The immune system plays an important role in tumor surveillance and destruction of malignant cells. In the late 1800's William Coley recognized that when the immune system is appropriately stimulated, it can prevent tumor progression and induce established tumor regression. However, only more recently has it been recognized that lymphocytes and the cytokine IFN- play key roles in preventing tumor development and influence the antigenic profile of malignant cells.1 These findings support the strategy of developing anti-cancer vaccines that effectively stimulate robust T cell mediated immunity against tumor-associated antigens (TAA). However, they also provide insight into some important obstacles (such as immune editing and the development of tumor escape variants) that must be overcome to translate the generation of antitumor immunity into clinically relevant therapeutic effects such as prolonged disease free survival and overall survival.2 To achieve optimal efficacy, augmentation of tumor-specific T cell numbers must be coupled with strategies to overcome the evasive and suppressive effects of the tumor on the immune response. Many novel approaches to stimulate T cell mediated anti-tumor immunity are in phase I, II and III clinical trials in the human oncology clinic. In contrast, the use of cancer vaccines in veterinary oncology remains in its infancy. In this lecture we will discuss some of the different cancer vaccine strategies designed to stimulate anti-tumor immunity and present examples of vaccines that have been employed in phase I/II clinical trials in dogs with hematological and solid malignancies. Ongoing and future clinical trials to evaluate novel veterinary cancer vaccines will also be presented and discussed.

CELL BASED CANCER VACCINES WHOLE TUMOR CELL VACCINES

In the veterinary arena, the majority of efforts to stimulate anti-tumor immunity have focused on active immunization strategies to increase the number of tumor-specific cytotoxic CD8+ T lymphocytes (CTLs) in vivo. These approaches have largely utilized whole tumor cell vaccines intended to prime functional, tumor-specific cytotoxic T cell responses. Since the whole antigenic repertoire of the tumor cell is used as the immunogen, it is likely that a polyvalent immune response directed against multiple TAA will be generated and that this polyvalent immune response will remain protective despite the tumor's best efforts to escape immune recognition by down regulating some targeted antigens. Furthermore, whole tumor cell based vaccines are particularly attractive in the veterinary arena where few bona fide TAA have been identified. Autologous whole tumor cells genetically modified to express immune stimulatory molecules and "helper" cytokines such as GM-CSF and IL-2 have been used to directly prime antigen-specific T cells in dogs with malignant melanoma, mammary 3 carcinoma and fibrosarcoma. In these cases, the tumor cell itself presents antigen to the patient's immune system. T cell responses against the presented tumor antigens are "helped" by GM-CSF and IL-2 secreted by the genetically modified tumor cell. Since this approach requires the patient's own, autologous tumor, it is somewhat limited in its practical application. Alternatively, allogeneic cells have been used in cancer vaccines to prime T cells.4,5 In this approach, allogeneic tumor cells are genetically modified to express cytokines such as GM-CSF and chemokines e.g. CCL21 that will promote macrophage, dendritic cell (DC) and T cell recruitment to the vaccination site. Irradiated tumor cells expressing these chemoattractive cytokines are administered intradermally to the patient, and are phagocytosed by recruited DCs and macrophages. TAA are processed by these cells and presented to the patient's T cells on the surface of these professional antigen-presenting cells. Multiple allogeneic, GM-CSF secreting whole tumor cell vaccines are now in phase III trials in humans and have shown varying degrees of success in stimulating tumor-specific CTL responses and inducing clinical 4,6-9 responses in human patients with prostatic, pancreatic and pulmonary carcinomas. Whole tumor cell vaccines that have been tested to date in the canine system include autologous and allogeneic whole tumor cells genetically modified to express human GM-CSF, co-stimulatory molecules (B7-1 and B7-2) or a xenogenic tumor-specific antigen.3,10,11 When used in the treatment of dogs with oral melanoma, these vaccines were well tolerated and induced objective clinical responses in <35% of canine patients. The safety and efficacy of an allogeneic hemangiosarcoma cell line transduced with canine GM-CSF is currently being evaluated in a phase I clinical trial for dogs

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with splenic hemangiosarcoma at the University of Pennsylvania. Patients with a histopathological diagnosis of splenic hemangiosarcoma are currently being vaccinated every three weeks following splenectomy in order to stimulate anti-tumor immune responses. The ability of the vaccine to stimulate anti-tumor humoral and cell mediated immunity is being evaluated and correlated with effects on disease free survival and overall survival. While the targeting of multiple tumor-derived antigens is important to promote polyvalent anti-tumor responses and reduce the risk of antigen variant loss, the use of whole tumor cell vaccines carries with it the risk of inducing autoimmunity to antigens that are not specific for malignant cells. However, no serious adverse side effects have been documented to date in either human or veterinary trials using whole tumor antigens as the antigenic payload.10,12-16

ANTIGEN-PRESENTING CELL VACCINES

In the human clinic, cell-based vaccination strategies to activate tumor-specific T cells and generate anti-tumor immunity have primarily focused on the use of autologous tumor peptide-pulsed dendritic cells (DC) to trigger antigen-specific T cell responses in cancer patients.17,18 In this approach, prior to administration, ex vivo generated, activated DC are "loaded" with TAA. These antigens are displayed on the surface of the DCs in the context of MHC I molecules and are presented to T cells. T cells that recognize presented TAA will become activated, proliferate, produce cytokines and kill tumor cells that present the same antigen. Peptide pulsed DCs have been used in clinical trials in human patients with melanoma, lymphoma and renal cell carcinoma and have been shown to be safe and capable of stimulating anti-tumor immune responses in vivo.19-21 In veterinary medicine, autologous, bone marrow derived DCs transduced with the melanoma specific antigen, gp100 were shown to be safe and capable of inducing tumor antigen-specific CTL responses in a small cohort of dogs with MM.22 Furthermore, the use of adenoviral vectors to target CD40 and deliver TAA to dendritic cells in vivo has shown efficacy in stimulating anti-tumor immunity in dogs.23 However, due to the small number of dogs in the study, no conclusions could be drawn regarding the therapeutic benefit of DC vaccination. While DCs are considered to be the most effective antigen presenting cells in their capacity to stimulate T cells they do not proliferate in vitro and large volume apheresis of DC precursors is required to secure sufficient cells to generate a vaccine. Large volume apheresis is problematic in pediatric patients and in smaller veterinary patients and as a result alternative APCs, such as CD40-activated B cells (CD40-B cells) are being evaluated for their ability to stimulate anti-tumor immunity in 24-26 Like DCs, CD40-B cells loaded with tumor antigen are capable of activating naïve T cells, boosting memory T cell vivo. responses and breaking tolerance to TAAs. However, unlike DCs, B cells can proliferate in vitro, such that numbers sufficient for vaccination can be generated from a small volume of peripheral blood. In both APC types, TAA can be supplied to the APC as peptides or as genetic material such as plasmid DNA or RNA. The use of whole tumor RNA, transfected into the APC, allows for gene transfer without the use of viruses or vectors and permits an MHC-independent, multiple-antigen targeting approach important in cancers where few TAAs have been described. The safety and efficacy of RNA-loaded CD40 activated B cells to stimulate functional antigen-specific CTL responses against TAAs in dogs with spontaneously occurring lymphoma has been evaluated at the University of Pennsylvania. In a phase I clinical trial evaluating the safety and efficacy of tumor-RNA loaded CD40-B cells in the treatment of canine lymphoma, this approach was found to be safe and well tolerated with preliminary evidence of efficacy at stimulating anti-tumor immunity.

DNA AND PEPTIDE VACCINES

Identification of antigens that are specifically expressed or over-expressed by tumor cells has led to the development of vaccines that are based on specific peptides or the DNA that encodes these specific TAAs. This approach carries less risk of inducing systemic autoimmunity than whole cell vaccines due to the fact that only a single TAA is targeted. However, targeting a single tumor protein or peptide exerts selective immune pressure that may promote down-regulation of the targeted antigen and the generation of resistant tumor "escape" variants. Therefore, genes and their proteins that are essential to tumor cell survival and so cannot be down-regulated by the tumor (e.g. survivin or telomerase) are receiving increased attention as potential targets for immunotherapy. In general, these approaches have been limited in veterinary medicine by our current restricted knowledge of canine MHC haplotypes (required for the design of peptide vaccines) together with the paucity of identified bona fide TAA in the dog. One exception to this is tyrosinase, a melanocyte specific gene expressed in both human and canine malignant melanoma. The first, and to date only cancer vaccine to receive a conditional product license for use in veterinary oncology in the US is 27 a DNA vaccine that encodes a xenogenic tyrosinase gene coupled with huGM-CSF. The vaccine is indicated for the treatment of dogs with stage II or stage III oral melanoma where local control has been achieved. The vaccine is delivered

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by transdermal route and is given every two weeks for a total of four doses. Thereafter booster vaccines are recommended every six months. Over 100 dogs with oral melanoma were treated prior to licensure and while clinical responses varied amongst patients, the vaccine was shown to be safety, immunogenic and capable of inducing clinical responses in some dogs with malignant melanoma.27,28 A recombinant human VEGF vaccine has also been evaluated in dogs with soft tissue sarcomas and has been shown to reduce circulating VEGF concentrations and induce clinical responses in a proportion of treated dogs.29 Taken together, these are exciting results and it is likely that over the next few years as TAA are identified in the dog and common MHC haplotypes are determined, peptide and DNA vaccines targeting TAA will be developed, optimized and marketed.

NON-SPECIFIC T CELL ACTIVATION

Immunomodulatory agents including Toll Like Receptor (TLR) agonists such as oligodeoxynucleotides (ODNs) with unmethylated CpG dinucleotide motifs and Bacillus Calmette-Guerin (BCG) have been used either alone or in combination with whole tumor cell vaccines, DNA vaccines and peptide vaccines to augment their immunogenicity and therapeutic efficacy in a wide variety of different tumor types in humans. These agents exert their immunostimulatory effects via TLRs expressed on the surface of APCs such as macrophages and dendritic cells. Following TLR engagement, APCs become activated and up-regulate cell surface expression of MHC class I and II molecules and co-stimulatory molecules, empowering them to prime tumor-specific T cells. TLR stimulated APCs also secrete chemokines that attract T cells increasing the likelihood of T cell interaction and activation. However, despite promising results in augmenting T cell priming and activation in human clinical trials and evidence of immunomodulatory effects of CPG and BCG in the dog their 30,31 Cationic liposome-DNA evaluation as potent immunomodulatory agents in the canine cancer patient remains limited. complexes have been evaluated alone and together with whole tumor cell lysates in an adjuvant setting to elicit nonspecific tumor activity in the dog.16,32 While the cationic liposomes have been used successfully as a transfection agent to delivery a transgene encoded by plasmid DNA in to canine cells, it is apparent that the liposome complexes themselves exert anti-tumor and anti-angiogenic effects.33 Adenoviral gene delivery of immune stimulatory agents such as CD40L and Flt3L have also been evaluated in dogs and have shown promising effects on immune function and tumor regression.34,35

BIO-ENGINEERED BACTERIA

The immune stimulatory properties of bacterial components have been used to promote the efficacy of cancer vaccines in stimulating anti-tumor immunity (see above). Bioengineered bacteria genetically modified to express TAA represent a unique way to effectively direct potent bacterial induced innate and adaptive immune responses against TAA. One bacteria hat has been used in this way is the gram positive, intracellular, facultative bacterium Listeria monocytogenes. 36,37 Administration of listerial recombinants engineered to express the universal TAA Her2-neu has been shown to result in robust anti-tumor immune responses that can lead to regression of established tumors in mice.38,39 Evidence of stimulation of both innate and adaptive immune responses together with inhibitory effects on regulatory or suppressor T cells make this approach an exciting new prospect in both the human and veterinary oncology clinic. A phase I clinical trial to evaluate the safety and efficacy of recombinant Listeria monocytogenes genetically engineered to express Her2-neu to treat canine osteosarcoma is due to start in 2010 at the University of Pennsylvania.

SUMMARY

To date cancer vaccines in human and veterinary clinics have focused on increasing the numbers of activated, fit, tumorspecific T cells. Much progress has been made in this arena in human medicine however increasing the numbers of tumor specific T cells alone often fails to provide clinically relevant therapeutic effects. These findings indicate that attention should now be paid to combination therapies that aid in optimizing the trafficking of tumor-specific T cells into the tumor site and those that counteract the immunosuppressive effects of the tumor microenvironment. In summary, our ever increasing understanding of the basic biology of cell mediated immune responses coupled with an increased ability to manipulate the size, specificity, longevity and location of these responses suggests that combination immunotherapies for the treatment of both human and veterinary cancer patients will becoming increasingly sophisticated and therapeutically efficacious in many malignancies in the near future and will become a common fixture in our armory against cancer.

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REFERENCES

1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. Shankaran, V. et al. IFNgamma and lymphocytes prevent primary tumour development and shape tumour immunogenicity. Nature 410, 1107-11 (2001). Clark, C.E. et al. Dynamics of the immune reaction to pancreatic cancer from inception to invasion. Cancer Res 67, 9518-27 (2007). Hogge, G.S. et al. Development of human granulocyte-macrophage colony-stimulating factor-transfected tumor cell vaccines for the treatment of spontaneous canine cancer. Hum Gene Ther 9, 1851-61 (1998). Eager, R. & Nemunaitis, J. GM-CSF gene-transduced tumor vaccines. Mol Ther 12, 18-27 (2005). Nemunaitis, J. Vaccines in cancer: GVAX, a GM-CSF gene vaccine. Expert Rev Vaccines 4, 259-74 (2005). Dummer, R. GVAX (Cell Genesys). Curr Opin Investig Drugs 2, 844-8 (2001). Hege, K.M., Jooss, K. & Pardoll, D. GM-CSF gene-modifed cancer cell immunotherapies: of mice and men. Int Rev Immunol 25, 321-52 (2006). Nemunaitis, J. et al. Phase 1/2 trial of autologous tumor mixed with an allogeneic GVAX vaccine in advanced-stage non-small-cell lung cancer. Cancer Gene Ther 13, 555-62 (2006). Ward, J.E. & McNeel, D.G. GVAX: an allogeneic, whole-cell, GM-CSF-secreting cellular immunotherapy for the treatment of prostate cancer. Expert Opin Biol Ther 7, 1893-902 (2007). Finocchiaro, L.M. & Glikin, G.C. Cytokine-enhanced vaccine and suicide gene therapy as surgery adjuvant treatments for spontaneous canine melanoma. Gene Ther 15, 267-76 (2008). Whitley, E.M. et al. Canine mammary tumor cells transfected with B7-1 or B7-2 stimulate proliferation of peripheral blood mononuclear cells. Anticancer Res 22, 2567-74 (2002). Alexander, A.N. et al. Development of an allogeneic whole-cell tumor vaccine expressing xenogeneic gp100 and its implementation in a phase II clinical trial in canine patients with malignant melanoma. Cancer Immunol Immunother 55, 433-42 (2006). Jaffee, E.M. et al. Novel allogeneic granulocyte-macrophage colony-stimulating factor-secreting tumor vaccine for pancreatic cancer: a phase I trial of safety and immune activation. J Clin Oncol 19, 145-56 (2001). Milazzo, C., Reichardt, V.L., Muller, M.R., Grunebach, F. & Brossart, P. Induction of myeloma-specific cytotoxic T cells using dendritic cells transfected with tumor-derived RNA. Blood 101, 977-82 (2003). Soiffer, R. et al. Vaccination with irradiated autologous melanoma cells engineered to secrete human granulocytemacrophage colony-stimulating factor generates potent antitumor immunity in patients with metastatic melanoma. Proc Natl Acad Sci U S A 95, 13141-6 (1998). U'Ren, L.W., Biller, B.J., Elmslie, R.E., Thamm, D.H. & Dow, S.W. Evaluation of a novel tumor vaccine in dogs with hemangiosarcoma. J Vet Intern Med 21, 113-20 (2007). Brossart, P., Wirths, S., Brugger, W. & Kanz, L. Dendritic cells in cancer vaccines. Exp Hematol 29, 1247-55 (2001). Steinman, R.M. & Dhodapkar, M. Active immunization against cancer with dendritic cells: the near future. Int J Cancer 94, 459-73 (2001). Hsu, F.J. et al. Vaccination of patients with B-cell lymphoma using autologous antigen-pulsed dendritic cells. Nat Med 2, 52-8 (1996). Kim, J.H. et al. Phase I/II study of immunotherapy using autologous tumor lysate-pulsed dendritic cells in patients with metastatic renal cell carcinoma. Clin Immunol 125, 257-67 (2007). Nestle, F.O. et al. Vaccination of melanoma patients with peptide- or tumor lysate-pulsed dendritic cells. Nat Med 4, 328-32 (1998). Gyorffy, S. et al. Bone marrow-derived dendritic cell vaccination of dogs with naturally occurring melanoma by using human gp100 antigen. J Vet Intern Med 19, 56-63 (2005). Thacker, E.E. et al. A genetically engineered adenovirus vector targeted to CD40 mediates transduction of canine dendritic cells and promotes antigen-specific immune responses in vivo. Vaccine 27, 7116-24 (2009). Coughlin, C.M., Vance, B.A., Grupp, S.A. & Vonderheide, R.H. RNA-transfected CD40-activated B cells induce functional T-cell responses against viral and tumor antigen targets: implications for pediatric immunotherapy. Blood 103, 2046-54 (2004). Mason, N.J. et al. RNA-loaded CD40-activated B cells stimulate antigen-specific T-cell responses in dogs with spontaneous lymphoma. Gene Ther 15, 955-65 (2008). Schultze, J.L. et al. CD40-activated human B cells: an alternative source of highly efficient antigen presenting cells to generate autologous antigen-specific T cells for adoptive immunotherapy. J Clin Invest 100, 2757-65 (1997). Bergman, P.J. et al. Development of a xenogeneic DNA vaccine program for canine malignant melanoma at the Animal Medical Center. Vaccine 24, 4582-5 (2006).

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25. 26. 27.

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28. 29. 30.

31. 32. 33. 34. 35. 36. 37. 38.

39.

Liao, J.C. et al. Vaccination with human tyrosinase DNA induces antibody responses in dogs with advanced melanoma. Cancer Immun 6, 8 (2006). Kamstock, D., Elmslie, R., Thamm, D. & Dow, S. Evaluation of a xenogeneic VEGF vaccine in dogs with soft tissue sarcoma. Cancer Immunol Immunother 56, 1299-309 (2007). Henry, C.J. et al. Evaluation of a novel immunomodulator composed of human chorionic gonadotropin and bacillus Calmette-Guerin for treatment of canine mast cell tumors in clinically affected dogs. Am J Vet Res 68, 1246-51 (2007). Milner, R.J., Salute, M., Crawford, C., Abbot, J.R. & Farese, J. The immune response to disialoganglioside GD3 vaccination in normal dogs: a melanoma surface antigen vaccine. Vet Immunol Immunopathol 114, 273-84 (2006). Dow, S. et al. Phase I study of liposome-DNA complexes encoding the interleukin-2 gene in dogs with osteosarcoma lung metastases. Hum Gene Ther 16, 937-46 (2005). Kamstock, D. et al. Liposome-DNA complexes infused intravenously inhibit tumor angiogenesis and elicit antitumor activity in dogs with soft tissue sarcoma. Cancer Gene Ther 13, 306-17 (2006). Candolfi, M. et al. Adenoviral-mediated gene transfer into the canine brain in vivo. Neurosurgery 60, 167-77; discussion 178 (2007). von Euler, H. et al. Efficient adenovector CD40 ligand immunotherapy of canine malignant melanoma. J Immunother 31, 377-84 (2008). Paterson, Y. & Maciag, P.C. Listeria-based vaccines for cancer treatment. Curr Opin Mol Ther 7, 454-60 (2005). Wood, L.M., Guirnalda, P.D., Seavey, M.M. & Paterson, Y. Cancer immunotherapy using Listeria monocytogenes and listerial virulence factors. Immunol Res 42, 233-45 (2008). Seavey, M.M. et al. A novel human Her-2/neu chimeric molecule expressed by Listeria monocytogenes can elicit potent HLA-A2 restricted CD8-positive T cell responses and impact the growth and spread of Her-2/neu-positive breast tumors. Clin Cancer Res 15, 924-32 (2009). Singh, R., Dominiecki, M.E., Jaffee, E.M. & Paterson, Y. Fusion to Listeriolysin O and delivery by Listeria monocytogenes enhances the immunogenicity of HER-2/neu and reveals subdominant epitopes in the FVB/N mouse. J Immunol 175, 3663-73 (2005).

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110TH PENN ANNUAL CONFERENCE - 2010

Wednesday, March 3, 2010 Thursday, March 4, 2010 Philadelphia, Pennsylvania

COMPANION ANIMAL: Behavior

UPDATE ON HUMAN DIRECTED AGGRESSION

Debra Horwitz, DVM, DACVB

Veterinary Behavior Consultations St. Louis, MO Aggression is the most serious and dangerous behavior problem that dog owners may need to deal with. Since there are many different types of aggression, making a diagnosis, determining the prognosis (the chances of safe and effective control and/or improvement) and developing an appropriate treatment plan are best handled by a veterinary or applied animal behaviorist. Multiple factors contribute to aggressive behaviors in dogs: genetic factors, biological factors of age and hormonal status, environmental variables, developmental influences, learning and experience all may influence the aggressive behavior of a dog. In some cases medical conditions can contribute to aggression, therefore before a behavior consultation it is essential that a dog have a complete physical examination and a set of blood tests (minimally a CBC, Chem Screen, T4 and TSH) to rule out organ dysfunction.

Aggression is usually defined as threat or harmful action directed to one or more individuals1. The behavior can consist of vocalizations, facial expressions, body postures, inhibited attacks and physically injurious attacks. There are many different methods to classify and categorize aggression in animals. The victim or target, the location where the aggression occurs or the type of aggression such as offensive or defensive are all used to classify aggressive behavior. In veterinary behavioral medicine, diagnostic categories classify aggression in animals. Those commonly cited include: dominance/conflict aggression, fear, possessive, protective and territorial, parental, play, predatory, redirected, pain induced or irritable, pathophysiological or medical and learned2,3,4. However, no standardization of diagnostic categories presently exists. In many cases, more than one form of aggression may be exhibited in any one animal since aggressive responses tend to be multi-factorial.

CLASSIFICATION OF AGGRESSION

DEMOGRAPHICS OF AGGRESSION

Caseloads of behavior referral practices reveal younger dogs presented more frequently for aggressive behaviors when compared to older animals. In dog bite reports filed with various agencies, mixed breeds are more common than purebred dogs. Interestingly, 85% of bites to people were from owned dogs, not stray dogs. Larger dogs seem to be responsible for more reported bites than smaller ones most likely due to the size of the dog and the subsequent damage from the bite.5 Between 1979 and 1996, there were more than 300 human dog bite-related fatalities in the United States6. Sacks et al (2000) looked at fatal dog bite reports over a 20-year period and found that, 24% of the deaths involved unrestrained dogs off the owner's property, 58% involved unrestrained dogs on the owner's property, 17% involved restrained dogs on the owner's property and < 1% involved restrained dogs off the owner's property. Their research also found that while recent fatal dog bite reports seemed to show an increase in fatal bites by Rottweilers and Pit Bulls, data from previous years show a different distribution. From 1979-1980 Great Danes caused the most reported fatal dog bites. Since 1975, more than 30 breeds of dogs have been cited in fatal dog bite reports. This does not even attempt to look at mixed breed dogs whose breed identification is difficult to determine. Guy (2001) looked at the demographic and aggressive characteristics of dogs in a general veterinary caseload7. Biting behavior was reported for 15.6% of all dogs, with the highest frequency of biting reported in dogs less than one year of age. Neutered male dogs were the most likely to be reported as having bitten in this study. Other studies have noted a positive association between neutering and aggression, but when dogs that were neutered specifically because they were aggressive were removed from the analysis, this association went away8. Guy (2001) also found that whether or not a dog was purebred did not significantly affect the reported frequency of biting. Guy further investigated risk factors for dog bites to owners and compared 227 biting and 126 non-biting dogs9. Significant risk factors for an outcome of biting were noted: "the dog being female (particularly if small), the presence of one or more teenage children in the home, a history of a pruritic or malodorous skin disorder which had received veterinary treatment, aggression over food in the first 2 months of ownership, the dog having slept on someone's bed in the first 2 months of ownership, and the dog having been given a significantly higher ranking for excitability based on its behaviour in the first 2 months of ownership." Small dogs were determined to be a higher risk of having bitten than large dogs and biting dogs were more likely to have exhibited fear of children, men and strangers. Other studies have shown a relationship between the management of the dog and

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110TH PENN ANNUAL CONFERENCE - 2010

Wednesday, March 3, 2010 Thursday, March 4, 2010 Philadelphia, Pennsylvania

aggression10. Children are often the targets of canine aggression and research has revealed which encounters are the riskiest11.

IDENTIFYING INDICATORS OF AGGRESSION

Canids have evolved a series of facial expressions and body postures designed to indicate their intention in encounters with other canids and use these same signals in their encounters with humans. Often the misunderstanding of these signals result in biting episodes. In dogs, staring, snarling (lifting the lip), growling, snapping and biting are all indicators of aggression. In addition, the position of the ears, tail and hair indicate potential responses and the underlying emotional state such as fear, anxiety, etc. A good understanding of aggressive indicators can help avoid injury. Not all dogs will go through the different signals in order, or slowly. The type of intruder, the distance to the dog, the speed of approach and prior encounters will all influence the dog's response. If a dog has learned that an aggressive response results in what the dog considers a beneficial outcome, the aggressive response is likely to be repeated. It is important to remember that aggression is just a symptom of the behavior that the dog performs. Without a complete behavioral history, it may not be possible to say more than the dog threatened and/or bit someone. A behavioral history should help establish motivation for the behavior and possibly a diagnostic category. A good understanding of aggressive body postures and facial expressions is necessary to identify types of aggression. Other information such as victim, location of the aggressive episode, location, number and severity of bite wounds, previous aggressive episodes, and other behaviors that the dog does will all factor into a diagnosis. These cases can be difficult and the risk and danger to the people who live and interact with the dog may be high. Assessing risk and helping to formulate a prognosis is a useful first step. Certain factors shown to affect risk and prognosis in aggressive dogs include: · Size of pet · Context · Predictability of behavior · Aggressive choices made by the pet o Severity of aggression · Severity of injuries sustained · Family composition-young children, elderly individuals, health issues · Ability to provide safety for people who come in contact with the pet · Willingness of those in contact with the pet to live with risk of further aggression · Ongoing medical disease An essential first step is the safety needs of the humans and other animals that may have to encounter the dog while it is undergoing treatment. Factors to consider include the level of aggression to date, the type of bites, the composition of the household, predictability of aggressive behaviors and owner control of the pet and circumstance. For some owners, creating a safe environment may not be possible either due to their constraints, pet constraints or both. Safety recommendations should include identifying all aggressive episodes and their stimuli and then avoiding them (such as keeping children separate from the pet, feeding in a separate room, keeping away from visitors), secure confinement must be created (crates, a room with a locked door, in the yard with a locked gate) if the pet's behavior cannot be predicted or controlled. Owners must realize that aggressive dogs are not cured, but rather controlled and perhaps will learn new responses, but may always be a risk in certain situations. Punishment is contraindicated because it can escalate rather than diminish aggression by causing pain, fear or anxiety. In fact, in many cases underlying anxiety is what has induced the aggressive responses. Owners must stop all punitive measures including "alpha rolls" and other attempts to dominate as these can increase aggression rather than diminish it12. Owners must be aware of potential liability and the pet kept away from visitors, strangers, and neighbors. If outdoors, the dog must be under adult supervision with the dog on a leash held by the adult. If possible and practical, muzzle training can begin. Often owners will bring up the discussion of new homes for aggressive dogs. This is very difficult to assess. Owners make excuses for their pet's behavior and assume that in another environment the dog will not engage in the aggressive responses. This is often not the case. Giving an aggressive dog to another home or shelter without full disclosure of the aggressive tendencies is risky others can be injured. Therefore, another role for the veterinarian is to help the client understand what a danger their pet may represent to others. This needs to be done realistically and empathetically because despite the behavior most owners love their pet.

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110TH PENN ANNUAL CONFERENCE - 2010

Wednesday, March 3, 2010 Thursday, March 4, 2010 Philadelphia, Pennsylvania

AGGRESSION DIRECTED TOWARD FAMILIAR PEOPLE

One of the most common types of aggression seen by veterinary behaviorists is aggression directed toward familiar people, usually family members. In the past, this has been labeled dominance-related aggression yet veterinary behaviorists believe that this is an overused and oversimplified explanation and diagnosis2. Practitioners of applied animal behavior interpret dominance hierarchies, ranking and how they interact in the human-dog relationship many different ways and may use varying criteria to define dominance13, 14, 15, 16. The concept of dominant and subordinate relationships between animals was developed from observation of animals (wolves, baboons, chickens) living in social groups.17 Social hierarchies arranged around dominant and subordinate relationships decrease the conflict associated with the allocation of critical resources, i.e. food, shelter, mates and territory18. However, one's dominance is within the context of a relationship with another individual, not of the individual himself and neither is dominance synonymous with aggression. An individual could be dominant in one relationship and not in another. Early studies of captive wolves mentioned a dominance hierarchy between individuals and the use of aggression to maintain this order, which then became extrapolated to domestic dog behavior. However, further studies on wild wolves did not note these types of relationships. Instead, the wild wolf pack functioned more like a family with the leader wolves taking more a parental role, allowing offspring to eat first and very little aggression19. This new research describes the role of wolf leaders as parental in nature. They lead, teach, and care for their pack members rather than control a competitive hierarchy. When mature, the offspring do not compete to overthrow the pack leader; instead, they leave the pack, find a mate, and start a family of their own. If those old theories do not apply to wolves, why should we consider them true of dogs especially in light of other findings that show how dogs themselves have changed due to domestication20? Certainly, this recent research calls into question the assumption that dogs would have a dominant/subordinate relationship with their owners. The complex interspecies relationship between a companion dog and its human family involves a variety of motivations and influences, including genetics, socialization, available resources, fear, conflicts, learning, behavioral pathology, and disease21. Communication is hindered because of misunderstood meaning and intent behind each species' communication methods. Most dogs that are engaged in unwanted or undesirable behaviors are anxious and fearful. For example, consider a dog that has stolen an object and is under the bed hiding, growling and snarling at the owner. The dog is using threat behavior and hiding to indicate that they are fearful (hiding) want to avoid confrontation (threat behavior), yet many owners force the dog out from under the bed and in the process may be injured. In this situation, the owner focused the stealing behavior and on attempts to retrieve the item unaware of the messages contained in the dog's behavior. Because they are not usually educated about how their pet communicates with them and the best way to communicate to their pet misunderstandings occur. Simple canine messages, which often indicate what the pet may do, which can be subtle and fleeting are missed. Consider a person approaching a dog who then lowers their head, averts their eyes and turns their head to the side. In dog language, this indicates an unwillingness to interact, yet the person may reach out to touch the dog and the dog snaps at their hand. So rather than being dominant, the dog was showing anxiety and avoidance behaviors that were not understood nor acted upon. If we continue to look at the dominance model to explain undesirable behaviors in our companion dogs, we exclude other possibilities: · When dogs perform an unwanted behavior, it is often because they thought it was the appropriate behavioral choice at the time. · Unless taught a new response, a dog is unlikely to pick a different one. · Dogs do not obey if they do not understand the request. · When dogs do not listen to a command, a competing emotion or stimulus (good or bad) that is stronger than their desire to perform the requested task might be catching their attention. · The dog was not trained to respond in all situations. · Owners were not taught the proper techniques to communicate with their dog. Many dogs that are aggressive to family members are fearful or anxious and exhibit conflict behavior22. Their behavior arises from uncertainty about their role or the response to their actions both assertive and deferential. Their future behavior is often determined by the responses to their threats, yet owners can be very inconsistent, allowing behaviors at some times and punishing them at other times. Caution should be exercised to avoid labeling all aggression toward family members as dominance motivated aggression since this may be simplistic. Whenever you are dealing with an aggressive dog, confrontations should be avoided, these will likely increase rather than decrease aggression since they increase anxiety, fear and defensive responses.

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110TH PENN ANNUAL CONFERENCE - 2010

Wednesday, March 3, 2010 Thursday, March 4, 2010 Philadelphia, Pennsylvania

Possessive aggression may be directed to humans or other pets that approach the dog when it is in possession of something that is highly desirable such as a favorite chew toy, food, or treat. While protecting possessions may be necessary if an animal is to survive and thrive in the wild, it is problematic when directed toward people or other pets in a household. What can be confusing for some owners is that it is not always food that brings out the most protective displays. Novel and highly desirable objects such as a tissue that has been stolen from a garbage can, a favored toy, human food, or a piece of rawhide are some of the items that dogs may aggressively protect.

PREVENTION AND CONTROL OF HUMAN DIRECTED AGGRESSION

Aggression directed toward family members can be complicated to treat. The first step is avoidance of all encounters known to elicit aggressive responses. Having predictable interactions with the dog, and daily activities that fulfill canine needs for exercise, social interaction and exploration are quite useful. Structuring interactions to earn all things and attention given for calm and quiet behavior makes things more predictable for everyone. Teaching the dog to be comfortably confined can also avoid aggressive encounters. Head collars, leashes, muzzles and gates all help to keep victims of aggression separated from the dog. Slow counter conditioning to triggers and desensitization to stimuli are also useful treatment modalities.

REFERENCES

Beaver BV, The veterinarian's encyclopedia of Animal Behavior. Iowa State University Press, Ames, Iowa, 1994 pp. 6 Reisner IR An overview of Aggression In: BSAVA Manual of Canine and feline Behavioural Medicine Eds. Horwitz, Mills and Heath, BSAVA, Gloucester, UK. 2002 pg. 181-194. 3 Houpt KA Domestic Animal Behavior for Veterinarians and Animal Scientists, Iowa State University Press, Ames, Iowa, 1991, pp. 34-74. 4 Landsberg G, Hunthausen W, Ackerman L, Handbook of behavior problems of the dog and cat. Saunders, Philadelphia, 2003, pp. 385-426 5 Wright, J. "Canine Aggression toward People", Veterinary Clinics of North America: Small Animal Practice, 1991, 21:2, 299314. 6 Sacks JJ, Sinclair L, Gilchrist J, Golab GC, Lockwood R. "Breeds of dogs involved in fatal human attacks in the United States between 1979-1998." JAVMA, 217:6 (2000) pp. 836-840. 7 Guy NC, Luescher UA, Dohoo SE, et.al "Demographic and aggressive characteristics of dogs in a general veterinary caseload" Applied Animal Behaviour Science. 74 (2001) 15-28. 8 Podberscek AL, Serpell JA "The English Cocker Spaniel: preliminary findings on aggressive behaviour" Applied Animal Behaviour Science, 47 (1996). 75-89. 9 Guy NC, Luescher UA, Dohoo SE, et.al "Risk factors for dog bites to owners in a general veterinary caseload" Applied Animal Behaviour Science. 74 (2001) 29-42. 10 Sullivan et al The management & behavioural history of 100 dogs reported for biting a person Applied Animal Behaviour Science 114: 149-158 (2008) 11 Reisner IR, Shofer FS, Nance ML. Behavioral assessment of child-directed canine aggression Inj. Prev. (2007) 13:348-351 12 Herron ME, Shofer FS,Reisner IR Survey of the use and outcome of confrontational and non-confrontational training methods in client-owned dogs showing undesired behaviors. Applied Animal Behaviour Science 117: 47-54 (2009) 13 Hallgren, A. Mother and Pups. Animal Behavior Consultant Newsletter, July 1990 Vol. 7:3 14 Trattner, A. Letter to the Editor. Animal Behavior Consultant Newsletter, Oct. 1990. Vol.7:4 15 Schilder, MBH, Netto, WJ. Letter to the Editor. Animal Behavior Consultant Newsletter. July 1991. Vol.8: 3. 16 John W.S., Bradshaw , Emily J., Blackwell , Rachel A., Casey. Dominance in domestic dogs -- useful construct or bad habit? Journal of Veterinary Behavior: Clinical Applications and Research/, May/June 2009, Pages 135-144 17 Alcock, J, Animal Behavior: An evolutionary approach. Edition 2. Sunderland, Mass, Sinauer Associates Inc. 1979. 18 Voith, VL, Borchelt, PL, Diagnosis and treatment of Dominance Aggression in dogs, In: Veterinary Clinics of North America: Small Animal Practice, Vol. 12:4, 1982, pp. 655-663. 19 Mech, D Whatever happened to the term Alpha Wolf? International Wolf Winter 2008 pp 4-8. 20 Gácsi1,M, McGreevy P., Kara E & Miklósi A Effects of selection for cooperation and attention in dogs Behavioral and Brain Functions, 5:31 (2009) 21 DeKeuster T., Jung H. Aggression toward familiar people and animals In: BSAVA Manual of Canine and Feline Behavioural Medicine second edition eds. Horwitz and Mills, BSAVA, Gloucester, UK (2009) pp 182-210 22 Luescher UA, Reisner IR Canine Aggression toward familiar people: A new look at an old problem In: VCNA Small Animal ed. Landsberg G, Horwitz D, Saunders, PA 38 (2008) 1107-1130.

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110TH PENN ANNUAL CONFERENCE - 2010

Wednesday, March 3, 2010 Thursday, March 4, 2010 Philadelphia, Pennsylvania

COMPANION ANIMAL: Behavior

AGGRESSION TOWARD UNFAMILIAR DOGS ON WALKS

Debra Horwitz, DVM, DACVB

Veterinary Behavior Consultations St. Louis, MO

INTRODUCTION

Aggression between unfamiliar dogs may have many motivations, fear, territoriality, competition and as a learned behavior. Inadvertent reinforcement of the behavior by owner actions can be a factor in aggression toward unfamiliar dogs1. Even when dogs are restrained by leashes fights can occur. Roll and Unshelm2 noted that dog fights in Germany occur most often in public with 74.8% on streets and sidewalks and 9.2% in public parks, and up to 56.3 % of the animals were off leash at the time of the fight and 13% of aggressors and 35% of the victims were on a leash at the time of the fight. When dogs fight, owners or other dogs within the vicinity may be injured due to redirected aggression. Redirected aggression is aggression (growl, snarl or bite) redirected to a person, animal or object other than that which evoked the aggression3. Although it is not always clear at the time it often appears that certain gestures or postures from either dog can elicit aggression. These can include placing head, or feet on the back of the other dog, assertive body postures such as eye contact, high tail and stiff legged approach. In a normal interaction, if one dog responded with subordinate body postures or cues, the encounter should end peacefully. However, things can escalate if one dog does not recognize and respond appropriately to subordinate cues. In other cases neither dog responds with subordinate cue and fighting escalates. In many situations the owner may inadvertently reinforce a tense and defensive behavior by tightening the leash and/or with their vocal cues and body posture. When the owner tightens the leash and draws the dog in closer they are usually doing so because they are unsure of how their dog may respond. However, these behaviors (leash tightening and tense posture) may signal to the dog that the impending approach is problematic, and therefore increase rather than decrease the dog's emotional arousal.

HISTORY TAKING

Naturally a behavioral history should include background information about the dog's early experiences with other dogs. Lack of exposure to other dogs as a puppy may result in an adult dog that has poor social skills. Traumatic early experiences such as attacks or fights may contribute to fear, anxiety and defensive responses. In addition all previous attempts to change or correct the problem must be explored and detailed. The aggressive responses should be explored in detail including location, distance to the other dog and the response itself. Every effort should be made to determine both a distance and response gradient. In other words, at what distance does the response first begin (perhaps with just alerting behavior, watchfulness and not full blown aggressive behaviors) and what does it look like. The owner should be encouraged to describe the response in very precise detail including body posture, vocalizations, and ability to control or divert the dog. The goal is to establish the distance at which the dog first notices another dog, what the response is at that time and also to determine when the response is at it's peak and where the other dog is at that time. Finally, how does the encounter end and when or at what distance does the dog return to a baseline controllable behavior? In other words, how does the behavior vary across distance and perhaps speed of approach? Is the behavior different when the dog is on a leash, off leash, behind windows or fences? Do these locations make a difference in the owner ability to control the dog? What have they done in the past to try and control or change the behavior? Have any of the interventions been useful or changed the response in any way?

DIAGNOSIS

In many cases the responses are a combination of fear based responses, anxiety and learned responses. In some cases it is apparent that the dog has poor social communication skills and does not read the social signals of other dogs appropriately. When the problem occurs on the territory or from behind fences, or windows it may be a territorial aggressive response.

PROCEEDINGS: Companion Animal ­ Behavior

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110TH PENN ANNUAL CONFERENCE - 2010

Wednesday, March 3, 2010 Thursday, March 4, 2010 Philadelphia, Pennsylvania

TREATMENT FOR INTER DOG AGGRESSION ON WALKS

Since the problem occurs on walks, all walks must be curtailed until the dog learns new responses. If the only way the dog goes outdoors to eliminate is on a walk then walks must be arranged at times and places where encountering other dogs is less likely. Treatment will focus on three areas, increasing control and ability to leave a potentially aggressive situations, systematic desensitization to other dogs and classical counterconditioning to the approach of other dogs6. The owner must also realize that high arousal situations are not good learning situations therefore, training must occur when the dog is calm. It is important for the owner gain control of their pet. Leashes are absolutely necessary (not retractable leashes) and the use of headcollars (Gentle Leader® Premier Pet Products) and/or muzzles strongly recommended for dogs that will be in situations with multiple dogs. The owners should also work at establishing reliable responses to basic obedience commands. The dog is also taught to sit and "watch" or "focus" on the owner while remaining relaxed. In addition the owner is taught an escape strategy that will allow them to leave situations where they cannot control the dog or unacceptable behavior is likely to occur. This is a command that teaches the dog to quickly turn 180 degrees and follow the owner in another direction so that the approaching dog is now behind them. This must be perfected prior to reinstating any walks and must occur each and every time the owner sees a dog at the predetermined distance that is likely to elicit the unwanted responses. The response should be prompt, and briskly but not frantically executed. Lastly, it is essential to establish a gradient of reinforcement for this dog. Usually these are food treats. The owner must find a food reward that is extremely enticing to the dog and will command their attention at nearly all times. Usually this is table food such as cheese, lunch meat etc, not biscuits. This food is reserved for training only and must not be given at any other time. Two common treatment strategies are often employed. One is to counter condition the dog to accept the approach and greeting of other dogs with subordinate or relaxed body postures. This most often is done slowly, with other dogs keeping their distance as the owner rewards calm, subordinate behaviors, usually with food. This is best accomplished first in unfamiliar parks and at some distance from other dogs until the dog is reliably able to assume calm and subordinate behaviors at the distant sight of other dogs. Gradually the dog is exposed to dogs at closer distances and in more familiar locations. The other approach is to classically counter condition the dog to associate something pleasant with the sight and approach of other dogs. The dog is taught to sit and focus on the owner for a food reward. Once that response is reliably established using the distance gradient created during history taking the owner is instructed to ask the dog to sit when a dog is visualized at the distance that will not elicit an unwanted response. At that time the dog is fed the food reward regardless of what they are doing. As the dog gets closer and it is likely the owner cannot keep the dog calm they stop all treats and give the escape command and turn and leave. The idea is to associate the approaching dog with good things, but keeping below the threshold of unwanted responses. Over time many dogs learn to sit quietly anticipating a food reward as the dog approaches without engaging in unwanted behaviors. Some owners are able to use a distraction method, such as the noise of keys jingling to keep the dog focused on them as they walk by other dogs without interaction. While dogs trained in this manner usually do not greet other dogs, they will walk calmly with their owners and not initiate fighting behavior. The goal of either type of treatment is for the dog to remain calm in the presence of other dogs. This may not result in the dog interacting appropriately with other dogs, but rather stay quietly by the owners side or stepping off the walking path and remaining calm. Greeting and playing with other dogs may not be possible.

TREATMENT OF TERRITORIAL AGGRESSION

Territorial aggression toward other dogs may only be exhibited when unfamiliar dogs are on the resident dog's property, or what the aggressor considers his territory. Some dogs get highly aroused at the sight of other dogs on their territory and may even attempt to jump fences, go through windows or doors to get to the intruder. Certainly, it is easier to prevent this type of aggression than to treat it. Dogs should not be allowed to engage in prolonged aggressive displays at windows, doors and fences at other dogs or people. Owners should strive early in the dog's life to get control of barking and other territorial displays. Some dogs that act territorial are actually fearful and this can often be determined in the history taking, concentrating on body postures and pet response to intruders who do enter the house or yard. Dogs that are aggressive toward other dogs may not be aggressive toward people on their property.

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110TH PENN ANNUAL CONFERENCE - 2010

Wednesday, March 3, 2010 Thursday, March 4, 2010 Philadelphia, Pennsylvania

Treatment for territorial aggression toward other dogs has several components. First, in the home the dog can be taught a "quiet" command so that barking displays can be halted. This is often best accomplished using a leash and headcollar for control. Alternately, visual access could be blocked to decrease the arousal level. In the yard, blocking visual access is also a possibility. The dog should not be allowed outdoor access without supervision since engaging in the behavior is very reinforcing and will cause it to continue and perhaps escalate. However, the cornerstone of treatment is to counter condition and desensitized the dog to the approach of other animals in its territory. The use of a headcollar and/or muzzle is necessary for owner confidence and control. This is accomplished by first teaching the dog a command incompatible with barking and lunging, such as a sit/stay. Food rewards are often helpful in the beginning so that the dog is relaxed and compliant. Then the dog is gradually exposed to dogs near the territory and praised for good behavior. At first it may be necessary to use dogs that the resident dog knows and recognizes and progress to unknown animals5. If the dog is an intact male, castration is recommended.

TREATMENT FOR FEAR BASED AGGRESSION

Fear based aggression toward unfamiliar dogs is probably very common in aggressive encounters with other dogs. The diagnosis is often made based on the body postures and reaction of the dog when faced with another dog. The fearful dog will often have the tail tucked, ears back and may lean against the owner or attempt to get behind them. They may be barking at the approaching dog and backing up at the same time. Often the dog is averting their eyes. On occasion this type of behavior can be precipitated by previous aggressive attacks from which the dog could not escape and sustained injury. However, once the dog learns that their aggressive responses will result in the dog or them leaving the situation their body postures may become more confident. Treatment is the often facilitated by the use of headcollars which not only give the owner control, but also seem keep the dog relaxed. The primary treatment is counter-conditioning and desensitization. However, the owner needs to be very careful not to reinforce fearful behavior by body contact, or vocal intonation. Also important is to set up situations for the dog to experience a non fearful interaction. This requires a good understanding of the stimulus gradient and the response gradient for the dog. Treatment is also facilitated by using highly valued food rewards tailored to each individual dog. It may be necessary to start with dogs that the dog knows, small dogs etc. until the dog is relaxed. It can be very difficult for owner to set up training situations. If owners continue to walk their dog, they must use a headcollar and be very cognizant of people approaching. If they see someone coming toward them with a dog, they should stop, put their dog in a sit/stay and reward calm behavior using valued food rewards. If the dog becomes anxious, the owner should quickly leave the area. The dog should not be placed in situations where they are unable to be calm and be rewarded for good behavior. Greetings with other dogs should be avoided. Dog parks should be avoided with all dogs that show aggression toward other dogs since interactions will be difficult to predict and control.

PHARMOCOLOGICAL INTERVENTION

In most situations medication is not indicated. If the dog is also extremely fearful and unwilling to go outdoors because they might encounter another dog then medication and/or pheromone collars may be useful.

REFERENCES

1. 2. 3. 4. 5. 6. Mertens, PA Canine Aggression In: BSAVA Manual of Canine and Feline Behavioural Medicine Eds. Horwitz DF, Mills DS, Heath S BSAVA: Gloucester, 2002 pp. 209-210 Roll A, Unshelm J Aggressive conflicts amongst dogs and factors affecting them. Applied Animal Behaviour Science 52: 229-242, 1997 Borchelt, PL. & Voith, VL. Classification of Animal Behavior Problems. Veterinary Clinics of North America: Small Animal Practice.12: 4. Philadelphia, W. B. Saunders Co. 1982. Pp. 571-585. Overall, KL. Animal Behavior Case of the Month. JAVMA 207: 305-307,1995 Hart, BL. & Hart, LA.: Aggressive Behavior in Dogs. Canine and Feline Behavioral Therapy, Lea & Febiger, 1985. p. 55. Horwitz DF, Neilson JC Blackwell's 5 minute Veterinary Clinical Companion: Canine and Feline Behavior, Blackwell Publishing, Ames, Iowa. 2007 pp. 71-78.

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110TH PENN ANNUAL CONFERENCE - 2010

Wednesday, March 3, 2010 Thursday, March 4, 2010 Philadelphia, Pennsylvania

COMPANION ANIMAL: Behavior

FELINE AGGRESSION TOWARD HOUSEHOLD CATS

Debra Horwitz, DVM, DACVB

Veterinary Behavior Consultations St. Louis, MO

OVERVIEW OF FELINE AGGRESSION

When possible, cats use body postures to attempt to avoid outright aggression. Therefore, understanding feline body language will help with diagnosis. Threatening body postures include hissing, piloerection, arching of the back and side presentation. Ear posture can be helpful as well; ears turned to the side and back usually indicate defensive aggression while ears turned back and up at the ends are often indicating offensive aggression. Cats that are restricted in movement may chose to fight when unable to flee resulting in defensive and possible fear-based motivations. Ability to get away and under something or up high can influence the expression of the aggressive response. Naturally, any medical or environmental issues can influence aggressive responses. Therefore, a good medical examination and behavioral history are essential for diagnosis and treatment. Historical questions should include when and where the aggressive episodes occur, who the victims are, what is the body posture and facial expression of the cat before, during and after the incident. Victim responses to the aggression may alter responses and should be discussed in the history. The frequency of aggressive episodes should be noted and will help determine both prognosis and treatment response. Finally, an attempt should be made to assess the intensity of the aggressive response, hissing, swatting, growling, chasing, 3 wrestling, biting and scratching .

FIGHTING BETWEEN HOUSEHOLD CATS

When cats within a household fight, several motivations are possible and contributory to the ongoing problem and should be identified to aid in diagnosis and resolution. Fights can occur between cats that have lived together for some time perhaps due to a change in social status or a traumatic event, fights may be the sequel to redirected aggressive behavior or another anxiety producing event, aggression may occur with the introduction of another cat, or due to illness or social changes within the home. Fear, anxiety and territorial responses all contribute to intercat aggression within a household.

HISTORY TAKING

All behavior cases benefit from thorough and complete history taking. Important information to collect includes the daily routine, pet-owner interactions and allocation of resources within the home. Identify all participants in the aggressive behavior. Detailed descriptions of several selected aggressive episodes will help to identify triggers, participants, owner responses and possible treatment options. Identifying all aggressive behaviors including blocking access to territory, staring, chasing, hissing, growling biting and attacks, facial expressions and body postures is necessary to get a comprehensive understanding of the problem. Identify and discuss any treatment options already attempted including implementation and what effect they may have had on the problem behavior. Ongoing behaviors of the cats involved should be examined noting signs of anxiety, fear and defensive behaviors (hiding, inappetence, lack of evidence of grooming) to determine their effect on treatment and resolution of the problem. Examine litter box use by all cats within the home since social issues often contribute to non-litter box usage.

DIAGNOSIS

After compiling a behavioral history, it should be possible to reach a diagnosis. Common diagnostic categories include territorial aggression, social status aggression, redirected aggression, fear aggression, irritable aggression, defensive aggression, offensive aggression and intermale aggression.

TERRITORIAL AGGRESSION AND SOCIAL STATUS AGGRESSION BETWEEN CATS

Fighting between cats can occur over territory or instability in social relationships. Cats may begin to fight when a young resident cat reaches social maturity (between 1-2 years of age), when an aging cat leaves the home or changes in their interactions with the other cats, another cat enters the home or resident cats experience a shift is social relationships.

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Wednesday, March 3, 2010 Thursday, March 4, 2010 Philadelphia, Pennsylvania

While some behaviorists disagree, others believe that cats do have structured social interactions and a social structure. However, as far as can be determined the basis is not on the same threats and deference system as dogs. Threats between cats can be covert, such as blocking access to locations, staring or supplanting. Chasing and overt aggressive threats such as growling, hissing, biting may also be evident1. Cats appear to show submission by crouching, turning the ears down and avoidance1. Speculation on space usage suggests that cats do not share space equally and additional cats in the household may result in some cats not having access to food bowls, resting places and litter boxes if placement of these resources is limited or restricted. Another possible theory is that cats fight to increase individual distance between them, and not about territory2. In territorial disputes, one cat (the aggressor) will usually chase another (the victim). Vocalizations such as hissing, growling and yowling often accompany the chase. This may result in one cat living in a restricted area to keep away from the aggressor. When territorial aggression is severe, cats may need to be separated at all times to avoid injury or alternate living arrangements found for some of the cats in the home. Drug therapy alone is rarely curative in these situations and in many cases; the prognosis for severe territorial aggression is poor.3 In social status aggression, there may be only occasional fights if access to litter boxes resting-places and food bowls is adequate. Some studies indicate that cats do not share space equally and that within a group of cats, certain individuals appear to be more controlling and assertive.4 This behavior was most evident in the use and access to certain resources within the home. In order to create harmony, it may be necessary to keep fighting cats separated unless supervised or using structured introductions. Introductions can be accomplished using food or play and the goal is to associate pleasant things with the presence of each cat. This technique is described below.

REDIRECTED AGGRESSION

Redirected aggression arises from the cat being in an aggressive or agitating circumstance, but unable to vent that aggression on the causative agent5. Stimuli that can potentially cause redirected aggressive behavior include the sight, sound or odor of another cat or other animal, unusual noises, unfamiliar people, unfamiliar environments and pain6. One such example is when a cat indoors sees another cat out of a window. The inside cat may become very agitated and begin to hiss and growl. If the owner or another animal walks into the room and diverts the first cat's attention, either accidentally or purposefully, they may become the recipient of an aggressive attack. When this happens between resident cats, the cats may no longer tolerate being together and fight whenever they see one another resulting in ongoing aggression. At other times, while one cat (the initial aggressor) may be fine, the other cat (initial victim) becomes defensive and the result is a fear-induced aggression. The fearful cat may growl or hiss at the sight of the other cat, run away or hide and become inactive. The victim behavior may then result in maintaining aggressive responses from the initial aggressor cat.

FEARFUL OR DEFENSIVE AGGRESSION

This can often be a sequel to fighting between cats. At times, the aggressor will no longer be threatening, but the victim is fearful and exhibits defensive behaviors. The cat assumes a fearful or defensive posture (crouched, ears flat, pupils dilated, piloerection and hissing, spitting or growling).3 When the aggressor sees these types of behaviors and body postures, they may respond aggressively as well and the problem continue. This type of aggression is treated with a counter conditioning and desensitization program described below. When not working with the cats they should be separated to avoid aggressive encounters and exacerbation of the problem.

IRRITABLE AGGRESSION

This is a likely diagnosis when other factors may contribute to aggression. These might include medical problems, changes in environment or social interaction with the owners. If these problems are resolved, the aggressive behavior may diminish.

TREATMENT MANAGEMENT TECHNIQUES

Immediately after a fight, owners must separate the cats until they both calm down. The best way to calm an agitated cat is to put the cat in a darkened room with food, water and litter box and leave it there. Some cats may be so agitated, that picking them up may be dangerous and injury to owners is possible. For those situations, herding the cat using a broom, lifting the cat with heavy gloves on or throwing a blanket over the cat so it can be lifted is safest. Keep the cat in the dark

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Wednesday, March 3, 2010 Thursday, March 4, 2010 Philadelphia, Pennsylvania

until it is calm which can take hours to several days. The owner can go in only to turn on the light, feed the cat and then leave. Once the cat begins to approach the owner calmly and with relaxed body postures, the cat may be ready for release. Long periods may be necessary for some cats to calm down and premature and/or early re-introduction may cause fighting to resume and prolong the problem. Therefore is inappropriate to try to bring the cats close together immediately following an aggressive episode. The most common error owners make in trying to resolve this problem is to attempt to bring the cats too close together, too soon. This often results in more fighting and makes re-introduction more difficult. Even after release of the aggressor cat, it may be necessary to create separate areas for food, resting places and litter boxes for each cat in order to create harmony. Do not cluster these materials together, but spread throughout the environment keeping in mind how the various cats access the space available to them. Some cats may only have access to certain household areas and if resources are not within those areas anxiety and house soiling may result. It also might be helpful for the aggressor to wear a quick release/elastic cat collar with a large bell that will forewarn the victim of their approach 7,8 allowing escape .

BEHAVIOR MODIFICATION EXERCISES

The focus is on counter conditioning and desensitization exercises to re-introduce the cats to one another. The goal is to allow the cats to be together without any aggressive behaviors (growling, hissing, chasing, staring etc.). Conduct introductions slowly, using food to facilitate calm, non-anxious behavior (counter-conditioning). The cats need to be far apart, so that they are relaxed (desensitization). Offer each cat a delectable food treat that they will eat. For safety and control, it is often advisable that each cat wear a harness and leash. If the cats will not eat, then they are too anxious and probably too close together and should be moved further apart. If the cats still will not eat, then separate until the next feeding. If the cats do eat at that time, allow them to remain together while they eat and then separate them. The next feeding is at the same distance. If things go well at that session, the next time the dishes can be moved closer together, but perhaps only 6-8 inches. If the cats are comfortable, sometimes they can be left together leashed, under supervision so that they can groom, and then separated again. Two feedings at the same distance without aggressive or anxious behaviors must happen before moving the bowls closer together. Clients should be cautioned that this is a slow process and not to rush. Allowing the cats to interact in an aggressive manner sets the program back and makes resolution more difficult. Separate the cats except for introductions and always supervise when they are together. It also may be helpful to switch litter pans between the cats to aid in familiarization. Another technique that may help is to rub the cats with towels and switch from one cat to the other to mix their scents. If the cats will not eat when they see one another, then it may be possible to get the cats to eat food treats while on opposite sides of a closed door. If the cats will eat at that time, use non-visual introductions for a few days and then try feeding across the room again. An additional method of introduction is with the use of a crate. Place one cat in the crate while the other cat is loose in the room. The goal is to allow the cats to become comfortable with the presence (both sight and odor) of the one another. Usually it is best to have the aggressor in the cage and the victim to be loose. This allows the victim to adjust the distance to their comfort level and move around in the presence of the aggressor. Over time, the occupant of the crate can be switch for the introductions with the victim inside and the aggressor outside. Do this cautiously and all interaction stopped if the aggressor threatens the victim in the cage. If the cats are uncomfortable if one is loose, both cats can be in carriers for the introduction. Use food to help calm the cats and reward the desired behavior. A similar technique using double baby gates on doorways to allow the cats to visualize each other without getting too close to one another is possible. A third way to integrate cats is with play therapy. If the aggression has not been severe, it may be possible to get the cats re-acclimated to one another through play using a Feline Flyer®. With each cat on either side of a slightly open door, introduce the Feline Flyer and see if they will play with each other. Finally, the use of Feliway® (CEVA) in a diffuser form has shown to be helpful in calming cats and facilitating reintroduction.

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110TH PENN ANNUAL CONFERENCE - 2010

Wednesday, March 3, 2010 Thursday, March 4, 2010 Philadelphia, Pennsylvania

PHARMACOLOGICAL TREATMENTS

For some cases, the addition of psychotropic medication can be helpful in resolving the aggression. The suggested drugs do not have FDA approval for this use and are an extra label drug usage. Prior to use, all animals should have physical examinations, laboratory screenings for liver and kidney function and in some cases, electrocardiograms. Signed consent and release forms are advisable. Owners should be informed of potential side effects and plan to be home to monitor their pet for the first 1-2 days of treatment. Several classes of drugs have been used to treat aggression in cats. In some cases, both the aggressor and the victim may need medication. · Fluoxetine and Paroxetine are selective serotonin re-uptake inhibitors used to treat aggression in cats. Selective serotonin reuptake inhibitors may take several weeks to become effective. Common side effects include constipation, urinary retention, anorexia, gastrointestinal signs, tremors, irritability and lethargy. Starting at a low dose for 1-2 weeks and gradually increasing the dose can minimize side effects. Toxicity due to serotonin syndrome is possible when more than one antidepressant is used and therefore this should be avoided. o Fluoxetine 0.5-1.0 mg/kg every 24 hours; 9 o Paroxetine 0.25-.5 mg/kg every 24 hours . · Clomipramine and Amitriptyline HCL are tricyclic antidepressants used in the treatment of aggression in cats. Clomipramine is a serotonin re-uptake inhibitor while amitriptyline and also inhibits both the reuptake of norepinephrine and serotonin. Most tricylic antidepressants have some anti-histamine actions and can interfere with thyroid medications. Clomipramine and amitriptyline must be given daily to be effective and can take 2-4 weeks to facilitate a change in behavior. Common side effects include tachycardia, urinary retention, and sedation, G.I.T. upset, mydriasis and a dry mouth. Amitriptyline is very bitter and therefore administration may be extremely difficult. Because of potential increases in heart rate, exercise caution in patients with cardiac disease and an EKG prior to use may be prudent. 10 o Clomipramine 0.25-0.5 mg/kg, PO every 24 hours . o Amitriptyline 0.5-1.0 mg/kg PO q 12-24 hoursError! Bookmark not defined.. · Benzodiazepines such as diazepam (1-2mg/cat every 12 hours) have been shown to be useful in aggression.11 Reports of hepatotoxic reactions have surfaced use this drug with extreme caution.12 Cats on benzodiazepines could disinhibit and the aggression may increase rather than diminish. Generally, this is not a drug of first choice due to potential toxic reactions. Because medicating cats can be a challenge the interest in administering medication via a transdermal route has become quite high. Although an attractive alternative, recent studies have unfortunately not been able to demonstrate good absorption of medication. Ciribassi et al showed that although Fluoxetine was absorbed through the skin in cats, the 13 relative bioavailability was only 10% of that for the oral route of administration . Mealey et al. looked at the systemic absorption of amitriptyline and buspirone after oral and transdermal administration to healthy cats and found that systemic absorption of both drugs was poor when compared to the oral route of administration14. Use medication for 6-12 weeks and if the behaviors have changed the animal is weaned off the medication by decreasing the dose 25% every 2-4 weeks while watching for a return of any aggressive indicators such as growling, hissing or chasing. If aggressive behaviors return, maintain the pet at the same dose for several weeks to see if the animal stabilizes before attempting to decrease the dose again. Drug therapy alone is rarely helpful without concurrent behavioral and environmental changes. Most cases of fighting between cats are amenable to treatment. Cases where aggression is severe and injury has occurred have a poorer prognosis. Many cases will still resolve if given enough time, often 6-20 months in severe cases.

REFERENCES

Crowell-Davis, SL., Barry, K, Wolfe, MA "Social behavior and aggressive problems of cats" Veterinary Clinics of North America: Small Animal Practice. May 1997, 27:3 pp. 549-568 2 Barry, K. "Intercat aggression in the household" AVMA Convention Notes, 1999. Veterinary Software Publishing 3 Marder, AR. "Diagnosing and treating aggession problems in cats" Veterinary Medicine, Aug. 1993, pp 736-742. 4 Bernstein P, Strack M A game of cat and House: spatial patterns and behavior of 14 Domestic cats (felis Catus) in the home. Anthrozoos, 1996; 11: 25-39. 5 Beaver, B The Veterinarian's Encyclopedia of Animal Behavior ,Iowa State University Press, Ames, Iowa, 1994. pp.224 6 Landsberg, G, Hunthausen, W, Ackerman, L "Feline Aggression" Handbook of Behavior Problems of the dog and cat 2nd edition, Saunders, Philadelphia, 2003 pp. 427-453.

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Wednesday, March 3, 2010 Thursday, March 4, 2010 Philadelphia, Pennsylvania

Heath, S "Feline Aggression" In: BSAVA Manual of Canine and Feline Behavioural Medicine Eds. Horwitz, Mills and Heath. BSAVA, UK. 2002, pp.225. 8 Lindell EM, Erb HN, Houpt KA "Intercat Aggression: retrospective study examining types of aggression, sexes of fighting pairs, and effectiveness of treatment" Applied Animal Behaviour Science, 1997, 55, pp. 153-162 9 Mills, DS. Simpson BS "Psychotropic agents" In: BSAVA Manual of Canine and Feline Behavioural Medicine Eds. Horwitz, Mills and Heath. BSAVA, UK. 2002, pp. 237-248 10 King JN, SteffanJ, Heath SE, Simpson BS et al "Determination of clomipramine for the treatment of urine spraying in cats" JAVMA 225:6 881-887 2004 11 Marder AR., "Psychotropic Drugs and Behavioral Therapy," Veterinary Clinics of North American: Small Animal Practice, Mar. 1991 21:2 pp. 329-342. 12 Center, SA. et al., "Fulminent hepatic failure associated with oral administration of diazepam in 11 cats," JAVMA 209:3 (August 1, 1996): 618-625 13 Ciribassi J, Luescher A, Pasloske KS et al. (2003) "Comparative Bioavailability of fluoxetine after transdermal and oral administration to healthy cats" AJVR 64:8 994-998. 14 Mealey KL, Peck KE, Bennett BS et al. (2004) "Systemic absorption of amitriptyline and buspirone after oral and transdermal administration to healthy cats" J Vet Intern Med. 18: 43-46

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110TH PENN ANNUAL CONFERENCE - 2010

Wednesday, March 3, 2010 Thursday, March 4, 2010 Philadelphia, Pennsylvania

COMPANION ANIMAL: Behavior

A CASE-BASED APPROACH TO ELIMINATION PROBLEMS IN CATS

Debra Horwitz, DVM, DACVB

Veterinary Behavior Consultations St. Louis, MO Feline house soiling (toileting in the wrong location) and marking are the most common behavioral problems of cats and the most annoying to our clients. Because house soiling can often be precipitated by medical problems, a good physical examination and urinalysis are essential for all patients that are house soiling. In a retrospective study of cats with problem elimination behavior, sixty percent of the cats had a history of FUS/LUTD1. Inappropriate elimination can also be a symptom of other medical abnormalities, such as hyperthyroidism, diabetes mellitus or liver disease. Urine marking is a common behavioral complaint of cat owners and can be very damaging to the household and the human-cat relationship. Studies have indicated a correlation between underlying social issues between household cats and urine marking and therefore relationships between cats should be explored2.

HISTORY FOR TOILETING AND MARKING PROBLEMS

A complete and thorough behavioral history is essential to determine what is going on and help formulate a treatment plan. Essential points include: Establishing the duration and progression of the problem behavior. What type of elimination is deposited outside of the litter box; urine, stool or both? Location of the elimination, i.e. vertical deposition of urine or horizontal deposition. Information on the litter box is useful and essential. Litter box size, covered box vs. uncovered box, litter type, number of boxes and rate of cleaning, box location should all be discussed. A diagram of the locations of inappropriate elimination The frequency of urination or defecation outside the litter box When (time of day) the owners find the elimination outside of the litter box. What substrate (material) does the cat eliminates on; different substrates for urine and stool? Information about the household routine and any changes in the home. How many other pets are in the household especially additional cats? Social relationship between cats in the household, including any overt signs of aggression (hissing, growling, chasing) and covert signs of aggression (blocking, staring, supplanting from spaces) All previous treatment attempts, behavioral, medical and pharmacological.

DIAGNOSIS

With thorough history taking you should be able to establish a diagnosis. The major diagnostic categories for feline inappropriate elimination include location preference, substrate preference, litter aversion, location aversion, and marking. House soiling can also be influenced by stress and anxiety as well as litter box factors such as size, cleanliness and placement. The use of a diagnostic category will help in the formulation of a treatment plan. Cats that mark with urine on vertical surfaces usually continue to use the litter box for elimination of both urine and stool. The diagnosis should focus on the location of the urine, the size of the urine spot and possible sources of stress in the 3 household. Marking in cats is often categorized as either sexual or reactional marking behavior . Cats will mark with urine 3 to attract mates and also urine mark in response to environmental changes and/or stress . Urine marks are often found in socially significant places such as owner possessions, laundry or in prominent locations. Marking behavior on horizontal locations is often revealed as small amounts of urine deposited in multiple locations. Although spraying is usually thought to be associated with intact animals, neutered animals will spray. Additionally, cats will often mark inside the house as a territorial response to the presence of other cats outside the home.

PROCEEDINGS: Companion Animal ­ Behavior

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110TH PENN ANNUAL CONFERENCE - 2010

Wednesday, March 3, 2010 Thursday, March 4, 2010 Philadelphia, Pennsylvania

TREATMENT FOR HOUSE SOILING

CHANGING ACCESS The goal is to try to limit a cat's access to the areas where they have previously soiled. Confinement can be used to try to find a litter usage pattern4. When the cat is in confinement, owners should check on the cat and try to ascertain when the cat urinates and defecates. When the owners are home, the cat may be out under strict supervision, and know where the cat is at all times. Confining a cat 24 hours a day is stressful and cats that use the litter box in confinement may still eliminate outside of the box when released. Confinement works best in conjunction with other environmental changes to increase litter box usage. INCREASING LITTER BOX ATTRACTION The litter pan should be friendly and very clean. Waste material should be scooped out 1-2 times a day. Owners must empty and wash the litter box frequently, perhaps weekly. The depth should be adequate, 3-4 inches seems preferred. Research has shown that some cats prefer the clumping materials to clay litter products5 it may be beneficial to switch to a clumping type product. Litter boxes must be easily accessible, in quiet locations and where the cats spend their time. Where and how to allocate litter boxes should be decided based in information on the household routine, the number of other cats within the home and the social relationship between individuals. In multi cat households there should be an adequate number of pans (one pan per cat) in different locations, not just an increase in the number of pans side by side. In some cases, the history shows a clear preference for a certain material. In selected cases, providing this material in the litter box may increase litter box use. If the cat will not use the litter box while in confinement, offering alternative boxes and substrates as a "litter trial" may be appropriate. A litter trial consists of offering the cat a choice of litter materials and boxes in the confinement spot and recording which material or box the cat prefers. Sometimes this choice is based on information in the history suggesting a substrate preference. MAKING PREVIOUSLY SOILED AREAS LESS ATTRACTIVE The owner must adequately clean the areas that the cat previously soiled and enzymatic cleaners work the best. Making the areas where the cat has urinated or defecated before aversive to the cat helps to prevent re-soiling. Commonly used techniques include food bowls, aluminum foil, plastic, potpourri, mothballs, sticky tape, and upside down plastic carpet runners. Be sure to be aware of the household composition before suggesting various items, i.e. mothballs may not be appropriate in households with small children or dogs.

A recent study by Tynes et al found that cats that urine marked usually did not have any urinary tract pathology6 but other disorders can influence urine marking. The rest of the treatment plan should be designed to address the underlying causes; intact cats should be neutered, scent profile in the home made constant, changes kept to a minimum and attempting to resolve the social issues between cats. Neutering is effective in reducing urine marking in only 90% of male cats and 95% of female cats, and even animals neutered prior to puberty may mark with urine7,8. When there are multiple cats in the home marking with urine may occur to delineate territory, or due to a lack of adequate resources or space or due the stress of too many cats and these issues must be addressed to aid in resolution. For cats that are dealing with social stresses within the home, individuals may benefit from "alone time". This allows the spraying cat to have access to an area (basement or bedroom) all by him/herself without the presence of the other cats in the household for 4-6 hours a day. The separate space should have a food bowl, water bowl, litter box and adequate resting and hiding locations. Social interactions with owners must also be regularly provided. Insuring adequate numbers of food bowls, resting places and litter boxes throughout the environment may help diminish social tension and perhaps spraying behavior. Cleaning urine spots and make the sprayed areas aversive using tactics such as placing potpourri at the spot, food bowls, motion sensors and keeping rooms blocked off are useful environmental changes. Recent research has shown that providing appropriate numbers of boxes, cleaning boxes regularly and cleaning 2 urine marks can decrease urine marking in the home . In other situations the number of cats in the home may need to be reduced to eliminate or decrease spraying behavior or permanent separation of cats may be needed.

TREATMENT FOR URINE MARKING

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110TH PENN ANNUAL CONFERENCE - 2010

Wednesday, March 3, 2010 Thursday, March 4, 2010 Philadelphia, Pennsylvania

Attempts should be made to limit the inside cats ability to visualize the outdoor cats9 and to get rid of those cats if possible. Blocking visual access out windows and doors, or closing the cat in a room where it cannot visualize outside cats is useful. In some cases motion sensors or fences may keep some cats out of the yard and away from windows. Since urine marking is a normal feline behavior, some cats will respond to the creation of an acceptable spraying spot for the cat. Owners can create an "L" shaped litter arrangement, two litter boxes, one horizontal with litter inside and placed inside one that is empty and vertical or just one litter box leaned against a wall. Some cats will use this set up and limit their urine spraying to this location only. Feliway® a synthetic pheromone spray or diffuser can also be very useful in the treatment of urine marking. Feliway® is synthetic cheek pheromone of cats and can be useful in decreasing or stopping spraying behavior10. In a study by Mills and Mills cats exposed to Feliway in the diffuser form showed a decrease in urine marks when compared to cats treated with placebo11. Feliway® is often effective in decreasing urine spraying caused by reactional stimuli such as changes in the cat's environment (moving, new pets, stress etc.). Pheromone spray has also been used to calm cats in new environments.

FOLLOW-UP FOR HOUSE SOILING AND URINE MARKING

Follow up should occur in 7-10 days. Owners should be encouraged to keep journals to document frequency of elimination both inside and outside of the litter box to help assess behavioral change and treatment success. Attempts should be made to determine the number of urine marks and whether their has been a decrease when compared to prior to institution of treatment.

PHARMACOLOGICAL TREATMENTS FOR HOUSE SOILING AND URINE MARKING

When considering drug therapy, a complete behavioral and medical history should be obtained prior to choosing a medication. Medications used for behavioral problems are not approved for use in cats, and therefore constitute extralabel drug usage. Complete serum biochemistry and possible cardiac work-ups are indicated prior to use. Owners need to be informed of potential side effects and extra label use. Consent and release forms should be obtained from owners. Frequent client contact for efficacy and side effects of drug therapy is necessary. Owners should be encouraged to be home for the first few dosages to assess effect or side effects. Drug therapy can be a helpful adjunct to behavioral treatment by decreasing the emotional arousal which may motivate urine marking. Drug therapy alone is rarely curative and is best used in conjunction with behavior therapy. Behaviors caused by stress, territorial stimuli, or anxiety are more likely to have some response to medication. Elimination outside of the litter box due to litter or location aversions, litter cleanliness problems, location or substrate preferences, are rarely affected by drug therapy. The most commonly used drugs are selective serotonin reuptake inhibitors, tricyclic 14, 11, 12, 13 . antidepressants, and rarely buspirone and benzodiazepines Fluoxetine (Pryor et al18 ) has been studied for the treatment of urine marking. Each household was given the same environmental plan and medication or placebo. Cats on medication showed a significant decrease in urine marks when compared to placebo with 6 out of 9 cats on drug showing no urine marking by week 7-8. Fluoxetine can take 2-4 weeks to show some effect on behavior. The most common side effects are gastrointestinal such as anorexia, nausea and diarrhea but may also include sedation, irritability and anxiety22. Clomipramine has recently shown efficacy in the control of urine spraying in cats15,16. Clomipramine is a tricyclic antidepressant that is a serotonin reuptake blocker and some norepinephrine reuptake blocking effects and the side effects of urinary retention, tachycardias, depression and inappetence are possible17. Two studies, Landsberg 19 , and King et al20 investigated the use of clomipramine on urine marking in cats. Clomipramine may take 2-4 weeks for an effect to be noted. Another study examined whether clomipramine differed from fluoxetine in reducing urine marking, whether the reduction of urine marking in cats continues in cats treated for a period longer than 8 weeks, and recurrence of urine marking after abrupt withdrawal of the medication is reduced in cats treated for more than 8 weeks and whether cats successfully treated with either medication that resume marking after drug withdrawal can be treated successfully again with the same drug regimen18. Although the study was small, the data revealed that the efficacy of fluoxetine and clomipramine was similar.

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110TH PENN ANNUAL CONFERENCE - 2010

Wednesday, March 3, 2010 Thursday, March 4, 2010 Philadelphia, Pennsylvania

Buspirone, an anxiolytic and partial serotonin agonist has been shown to be more effective than either diazepam or progestins in reducing spraying behavior with a lower reoccurrence rate of spraying when medication was discontinued16 but is no longer a first line drug of choice. The side effects noted with Buspirone include disorientation and gastrointestinal symptoms and on occasion increased aggression toward other cats or owners and paradoxical excitement.16 Benzodiazepines are GABA synergists and are useful in the treatment of anxieties in humans. Diazepam has been used for spraying and other behavioral problems in cats22. Reports of irreversible fatal liver failure in cats on diazepam have been documented19, 25 and they are rarely used at this time for urine spraying. Drug Class SSRI TCA Azapirone Benzodiazepine Dose Range 0.5-1.0 mg/kg 0.25-1.0 mg/kg 0.5-1.0 mg/kg 0.2-0.4 mg/kg Frequency q24h q24h q12h q12-24h Route PO PO PO PO

Fluoxetine Clomipramine Buspirone Diazepam

Medicating cats can be a challenge and the interest in administering medication via a transdermal route has increased. Although an attractive alternative, recent studies have unfortunately not been able to demonstrate good absorption of psychotropic medication. Ciribassi et al showed that although Fluoxetine was absorbed through the skin in cats, the 20 relative bioavailability was only 10% of that for the oral route of administration . Mealey et al. looked at the systemic absorption of amitriptyline and buspirone after oral and transdermal administration to healthy cats and found that systemic absorption of both drugs was poor when compared to the oral route of administration21. Appropriate dosages for transdermal administration of these medications has not yet been established.

FOLLOW UP FOR DRUG THERAPY

Owners should be contacted at least every 2 weeks when first beginning medication. If the house soiling/marking behavior responds to medication it should be continued for 8-12 weeks. If the behavior has not returned, an attempt can be made to wean the cat off of medication. The dosage is decreased by 25% a week while watching for a return of urine marking. If the cat does begin to mark, it is recommended to remain at that dose for 2 weeks to determine if the urine marking will stabilize. If urine marking ceases, an attempt can be made to decrease the dosage again. If urine marking is ongoing, the dosage can be increased to the previous effective level. If a cat must remain on medication for long periods of time, repeat blood chemistries are prudent to check for liver or kidney value changes.

REFERENCES

Horwitz DF., "Behavioral and environmental factors associated with elimination behavior problems in cats: a retrospective study," Applied Animal Behaviour Science , 52 (1997) 129-137. 2 Pryor PA, Hart BL, Bain MJ, Cliff KD, "Causes of urine marking in cats and the effects of environmental management on frequency of marking" JAVMA, 2001; 219:12: 1709-1713. 3 Dehasse J. "Feline Urine Spraying". Applied Animal Behaviour Science, 52(1997) 365-371. 4 Horwitz, DF. "Housesoiling by cats" In: BSAVA Manual of Canine and Feline behavioural medicine. Eds. Horwitz, Mills and Heath. BSAVA, Gloucester UK, 2002, pp 97-108. 5 Borchelt, PL, Cat elimination behavior problems, Veterinary Clinics of North America: Small Animal Practice, Vol. 21:2 March 1991 ed.: 254-265. 6 Tynes VV, Hart BL, Pryor PA et.al " Evaluation of the role of lower urinary tract disease in cats with urine-marking behavior" JAVMA 223:4 2003 7 Hart BL, Barrett RE. "Effects of castration on fighting, roaming, and urine spraying in adult male cats". JAVMA, 163:290292. 1973. 8 Hart BL, Cooper L. "Factors relating to urine spraying and fighting in prepubertally gonadectomized cats" JAVMA, 184: 10; 1255-1258, 1984. 9 Cooper LL., Feline Inappropriate Elimination. Veterinary Clinics of North America: Small Animal Practice, 27(3) pp. 569-600. 1997. 10 Mills DS., Mills, CB, "Evaluation of a novel method for delivering a synthetic analogue of feline facial pheromone to control urine spraying by cats" Veterinary Record, 2001, 149: 197-199. 11 Marder, AR, "Psychotropic Drugs and Behavioral Therapy," Veterinary Clinics of North America: Small Animal Practice, 1991; 21(2):329-342.

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Hart, BL., et. al., Effectiveness of Buspirone on Urine Spraying and Inappropriate Urination in Cats, JAVMA 1993; 203:2: 254-258. 13 Overall, K. L., Practical Pharmacological Approaches to Behavior Problems, Behavior Problems in Small Animals Ralston Purina Specialty Review 1992: 36-51. 14 Pryor PA, Hart BL, Cliff KD et al (2001) Fluoxetine hydrocholride for urine marking in cats: a double blind, placebocontrolled clinical trial. JAVMA 219: 1557-1561 15 Landsberg GM, Wilson AL "Effects of Clomipramine on Cats presented for Urine Marking" JAAHA 41: 3-11 2005. 16 King JN, SteffanJ, Heath SE, Simpson BS et al "Determination of clomipramine for the treatment of urine spraying in cats" JAVMA 225:6 881-887 2004. 17 Mills DS, Simpson BS "Psychotropic Agents" In BSAVA Manual of Canine and Feline Behavioural Medicine. Eds: Horwitz, Mills and Heath. BSAVA, Gloucester, UK 2002 pp. 237-248. 18 Hart BL, Cliff KD, Tynes VV, Bergman L (2005)"Control of urine marking by the use of long-term treatment with fluoxetine or clomipramine in cats" JAVMA 226: 378-382 19 Elston T.H., Rosen, D., "Seven Cases of Acute Diazepam Toxicity," Proceedings of the Academy of Feline Medicine (1993): 343-349. 20 Ciribassi J, Luescher A, Pasloske KS et al. (2003) "Comparative Bioavailability of fluoxetine after transdermal and oral administration to healthy cats" AJVR 64:8 994-998. 21 Mealey KL, Peck KE, Bennett BS et al. (2004) "Systemic absorption of amitriptyline and buspirone after oral and transdermal administration to healthy cats" J Vet Intern Med. 18: 43-46

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COMPANION ANIMAL: Dermatology

KILLING BAD THINGS: BACTERIA

Gregory C. Griffeth, DVM, DACVD

Staff Dermatologist ­ Matthew J. Ryan Veterinary Hospital University of Pennsylvania, School of Veterinary Medicine Philadelphia, PA

The treatment of infections is an absolute necessity in veterinary dermatology. The skin is a distinctly non-sterile location, so almost any primary problem is likely to become secondarily infected. Add to this the truly contagious dermatoses, and the vast majority of patients which present with dermatological disease have at least one infection...and many have two or more. Staphylococcal pyoderma is the most common infectious problem we address. The majority of this discussion will be targeted at this infection. However the basic theory and common techniques of managing pyoderma apply to all microbial infections. Perhaps most importantly, remember that any infection is a very complicated interaction between the host organism and the pathogenic organism(s). The old ideas of infections simply being "bugs growing on hosts" has given way to a deeper understanding of the intricate details of specific binding, quorum sensing, biofilm generation, and the transfer of molecular information which allows resistance to antimicrobials among infectious organisms. Similarly, the innate and adaptive segments of the host's immune system are both deeply complex, active systems that detect, respond, attack locally, signal systemically, and self-regulate aggressively in response to pathogenic organisms. Consideration of the underlying disease(s), site of infection, possibility of resistance, and immunological status of the patient can all lead to better-chosen therapy.

SPECIFIC SYSTEMIC ANTIBIOTICS

Antibiotics are the most-used drugs in dermatology. The epidermis is a particularly difficult tissue to treat with antibiotics: There is no blood flow directly to the epidermis, the stratum corneum prevents penetration of topicals from above, and the basement membrane slows diffusion from the dermis below. For this reason, dermatological dosing of antibiotics is typically of high dose and long duration to allow effective concentrations of medication to accumulate at the desired site. For staphylococcal pyoderma, antibiotics are given for 3 weeks for folliculitis (superficial) and 6 weeks for furunculosis (deep)...and often for longer to ensure at least one to two weeks of therapy beyond clinical resolution. This is 2-5 times the duration given for "normal" infections; educating owners as to why this is helps greatly with compliance. In general, the frequency of dosing is dependent upon the drug used. For time-dependent drugs like cephalosporins, the drug concentration should be well above the MIC for the entire inter-dose interval. For concentration-dependent drugs like fluoroquinolones, it is best to have the drug concentration exceed MIC greatly...spike...for a short period during each interval. Historically, this has meant q8-12 hours for the former, and q24-48 hours for the latter. However, with the recent availability of antibiotics with extended half-lives, it can be difficult to guess correct dosing regimes by drug class....it is always good practice to check Plumb's, Papich, and the latest few CVT books to determine the correct approach. Further, the slow diffusion of drugs to the epidermis can make the relationship between dose, frequency, and efficacy even more nebulous...an even better reason to look up derm doses until you are very familiar with any antibiotics used for skin disease. The target organism for almost all pyodermas is S. pseudintermedius (it used to be called S. intermedius until someone started playing around with a PCR machine.) Other staphylococci are seen frequently as well, including S. schleiferi, S. hyicus, and S. aureus This makes it easy to determine a few drugs which should NOT be used empirically for skin infections: Naked penicillins: PenG, PenV, ampicillin, amoxicillin. The majority of pathogenic staph species produce penicillinases, which render these drugs useless. All your friends will laugh at you if you treat pyoderma with amoxi.

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Tetracyclines: There is a very significant presence of the tetM resistance gene in veterinary staphylococci. While this class (specifically doxy) is regaining some importance in veterinary dermatology, and is occasionally useful when others fail, the empirical use of tetracyclines for pyoderma patients is a Bad Idea. Macrolides (early generation): Lincomycin and erythromycin are not good choices for Staph...the side effects are great and resistance is common. Not all is lost with the macrolides, however...see clindamycin, below. Staphylococci cause 99% of bacterial skin infections. Consideration should be given to all aspects of the infection, not just the causative organism and its antimicrobial sensitivity. Therapy for folliculitis should be continued for at least 3 weeks. Therapy for furunculosis should be continued for at least 6 weeks. Penicillins, tetracyclines, and most macrolides are not useful for treating pyoderma. First line antibiotics, for pyoderma: Penicillinase resistant beta-lactam drugs are the best empirical choice for Staph infections. The Gram-+ cocci are prime targets for these antibiotics, as they do not possess the complex cell membrane/wall structure of the G-neg rods. Cephalosporins are naturally resistant to penicillinases, which is how and why they were discovered. Aminopenicillins with beta-lactamase inhibitors, clavanulate being the oral example, are another choice; they protect the penicillins from destruction by bacterial enzymes, overcoming that mechanism of resistance. The following drugs are the best choice for uncomplicated folliculitis or surface pyoderma:

st Cephalexin ­ This is the prototypical first-generation cephalosporin. Cefadroxil is equally effective, and is the only 1 gen ceph approved for animals. GI upset is seen fairly often, especially at the higher derm doses. Cephalexin is cheap; cefadroxil varies. Cephalexin and cefadroxil should be administered with food at 30mg/kg q12 hours. Three weeks (one past resolution) for surface and superficial pyoderma, six week (two past resolution) for deep pyoderma.

Coamoxiclav (Clavamox, Augmentin) ­ This is useful for smaller animals, and may be somewhat less likely to cause GI upset. It is fairly expensive. Dosing is at 20mg/kg by mouth with food every 12 hours. As will all antibiotics, three weeks (one past resolution) for surface and superficial pyoderma, six week (two past resolution) for deep pyoderma. Cefpodoxime (Simplicef, generic) ­ This is a third-generation cephalosporin with a very long half-life in dogs, so can be administered once daily. It is expensive. Anecdotally, there are fewer GI side effects with this drug than most other oral beta-lactams. Dose is 5-10 mg/kg po q24h. Second-line antibiotics for pyoderma: There are many cases in which primary empirical therapy is not possible; often this is based on adverse drug reactions or medical conditions which limit the usefulness of the above drugs. Also, for recurrent cases, or those which have been treated with suboptimal doses or durations of the above medications, second-line drugs may be indicated to reduce the likelihood of drug failure due to resistance. However, any clinically resistant infection should be cultured before changing antibiotics. Clinically resistant means a documented infection which failed to respond to appropriate primary therapy. Of course standard trouble-shooting, with a detailed history of exact administration techniques, rechecking pill vials to ensure proper labeling and that the prescribed drug was actually dispensed, and rechecking of possible drug interaction is essential. However, if it is truly a failure of response, culture is definitively indicated. If owners refuse culture, I will consider administering one of the second-line drugs without a culture. Maybe. Clindamycin (Antirobe, Clinsol) ­ this macrolide is very effective against Staphylococcus spp. It also concentrates very well in skin and soft tissue abscesses, which may make its use for deep pyoderma even more effective. Pseudomembranous colitis (associated with Clostridiuim difficile), a known side effect of clindamycin, limits its use in humans. This problem is quite rare in our patients, so you will see its use much more commonly in veterinary medicine. Clinsol liquid is fairly easy to administer to cats as well. For uncomplicated cases, dosing of 11mg/kg po q24h is as effective as bid dosing, adding to convenience and compliance. Use 11mg/kg q12h for complicated cases or when treating known MR or MDR bacteria. Potentiated sulfas (trimethoprim+sulfamethoxazole/sulfadiazine [TMS], ormetoprim+sulfadimethoxine [Primor]) ­ These antimicrobials are old. Sulfas were around before penicillin. However, with the addition of DHFR inhibitors in the 60s, the usefulness of sulfas became much greater -- inhibition of folate synthesis at two different steps in the cascade is very effective, and resistance is much more difficult to attain. The ormetoprim drug (Primor) is labeled for once daily use, and has been anecdotally associated with fewer adverse effects. TMS is known for its many adverse effects; most of these are dose and duration related, but some are idiosyncratic. It should be remembered that TMS side effects are indeed unusual,

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even if more common than other drugs. TMS is very inexpensive. Primor is significantly more costly, even if less frequent dosing is considered. Tertiary antibiotics for skin infections: These drugs, because of their limited empirical efficacy, significant risk, cost of therapy, or public health ramifications, should only be used in limited cases when cultures clearly indicate necessity and expected efficacy of their use. Fluoroquinolones: (enro-, marbo-, orbi-floxacin). The fluoroquinolones are the second most recent "new" antibiotic class discovered. They are quite broad spectrum (although useless against anaerobes), and are typically well tolerated orally. Penetration into abscesses or other limited-access areas is usually very good. They are very expensive, especially in larger animals at higher doses. This is the first drug on this list that has greater-than-normal public health significance. Fluoroquinolones are the last oral drug usable for many human infections; they are highly significantly associated with colonization by MRSA in humans, especially when suboptimal doses are used; and most MRSA strains are resistant to FQ as well. Because of this, and the extended duration of use in skin disease, we do not recommend FQ for skin infections unless clearly indicated by culture. Even if the local infection is controlled with this drug, the effect on normal flora and nonpathogenic Staph, as well as the exposure of all of the gut bacteria to the drug makes possible risk of later resistant infections greater. Chloramphenicol ­ this is another older drug which has seen waning use in the wealthier societies. There is a very low risk of bone marrow disease in humans who take this drug...even only as ophthalmic ointment. The marrow necrosis is lethal without marrow transplantation. Therefore, use is strongly limited. However, the chemical is extremely inexpensive to manufacture, and maintains its place in the WHO's list of essential medications. It is broad spectrum and penetrates fairly well. Required dosing is q8h (q6h when used in humans) which limits compliance. Rifampin ­ Rifampin's most common use has been as part of multi-drug therapy for tuberculosis, although it is used in veterinary medicine with macrolides for Rhodococcus equi in foals. It is effective against many MR staph strains, but requires q8h dosing and is associated with fairly frequent hepatotoxicity. Vancomycin ­ vancomycin is a last-resort drug for highly resistant Staph and Enterococcus infections. It is only systemically active when given parenterally. Oral forms are available, but are for use against C. difficile in patients with life-threatening colitis, as it remains in the GI tract. Oral vancomycin has no legitimate use in veterinary dermatology. Linezolid ­ this is the only "new" antibiotic class developed in the last 25 years. It is the only available option for my humans with severe or MDR Staph or other Gram positive infections. Resistance has already been noted. Oral therapy with linezolid for a Labrador retriever would cost $3200 for three weeks. The use of linezolid or any other oxazolidinone antibiotic in non-human patients is absolutely contraindicated for public health/ethical reasons. Cefovecin ­ this third generation injectable antibiotic has been aggressively marketed for skin and UT infections for a few years. It is very highly protein bound, and is not significantly metabolized. Therefore, its duration in the patient is measured in weeks. The major advantage of this drug is ease of administration. However, in any case of skin infection, orally administered drugs would be strongly preferred. They can be stopped in case of side effect and systemic concentration is, on average, high while administered and drops off rapidly after use, reducing unnecessary exposure of bacterial populations to antibiotics. This drug is very expensive for larger animals. Perhaps most importantly, the drug is unstable: a 10 ml vial is only good for one month after dilution, but treats 100kg of patient. The PennVet pharmacy requires patient to purchase a whole vial ($350) for this reason. Pfizer is counseling vets to provide "alternative pricing" when using this drug.

CULTURE AND SENSITIVITY:

Bacterial culture and senstivity analysis is a very sensitive but poorly specific test for skin and ear disorders. Dogs' hygiene is somewhat suspect: the walk where they poop, they lick themselves, they roll in anything smelly. A culturette taken from the average healthy dog may grow up to a half dozen different species of possibly pathogenic bacteria. Concurrent cytology is essential to help identify which (if any) of the bacteria isolated is the likely culprit.

The rest of the session will be looking at a few C&S reports, and making some sense of them.

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110TH PENN ANNUAL CONFERENCE - 2010

Wednesday, March 3, 2010 Thursday, March 4, 2010 Philadelphia, Pennsylvania

COMPANION ANIMAL: Dermatology

KILLING BAD THINGS: MITES & INSECTS

Gregory C. Griffeth, DVM, DACVD

Staff Dermatologist ­ Matthew J. Ryan Veterinary Hospital University of Pennsylvania, School of Veterinary Medicine Philadelphia, PA Ectoparasites are a fact of life for the majority of the animals on the planet. While the excellent hygiene and bathing habits of humans has reduced this worry for people (at least in wealthy societies,) infestation continues to be a significant problem for domestic and exotic animals. By definition, ectoparasites are in close contact with the skin, and the majority of clinical signs noted are cutaneous; the dermal appendages often suffer greatly as well. The most important general principal in parasite control is understanding the life cycle of the infesting organism. This can allow significant advantages, such as intervention off the host, seasonal treatment, and reproductive control techniques...which are often less expensive, more effective, and/or safer than treating already-infested animals. It also allows better targeting of therapy in time and space, again with significant benefits to the client and patient. It is also very important to discern the specific needs of the patient and client. Lap dogs, show cats, competition horses, breeding colonies of ferrets, working animals, and patients with complicating medical problems all have different needs which will dictate different treatment. Owner compliance, finances, and attitude also play an important role in choosing parasite control programs. Perhaps most importantly, infestations often present in different ways; specific presentations can change treatment and prognosis greatly. Stating that a dog, for instance, "has demodex" is woefully inadequate without details of patient species, breed, age, and condition; lesion distribution; duration of signs; species of pathogen; and response to prior therapy. For mites, especially, understanding the different presentations will lead to more effective therapy and less risk for the patient undergoing treatment.

FLEA CONTROL

We have come a very long way since using shampoos and dips that were almost as toxic to the patient as to the fleas. There are currently ten veterinary-only monthly flea control agents available in the USA. There is an oral tablet that will kill every flea on an animal in 60-90 minutes. Because of the plethora of effective agents, veterinarians have many choices available to allow them to prevent ectoparasites while maximizing the comfort and convenience for the client and patient. Flea control agents fall into two categories: adulticides and juvenile control agents. Adulticides include the majority of available products including fipronil, imidacloprid, nitenpyram, dinotefuran, spinosad, metaflumazone, pyrethrin, and permethrin. The latter two, developed from chemicals in nature, are also detectable by fleas (and other arthropods) and, therefore, have some repellant activity. While good at killing mature fleas, most adulticides are not very useful against pupae or other juvenile forms. While it is true that dead fleas cannot reproduce, and that the continued presence of an effective adulticide on all exposed animals will eliminate the flea life-cycle from a dwelling area within weeks to months....that period can seem like a very long time. Further, it only takes a lapse of 2-3 weeks in adulticidal flea control to load an environment with thousands of pupae. Juvenile control agents are very effective at preventing the ingress of a breeding population of fleas from the environment. When applied to the environment, they can eliminate pupa emergence in a few days. When applied to animals, they can render any fleas that arrive unable to produce viable offspring. However, they are useless against adults, and any patient with large numbers of fleas will need adulticide therapy, as will those exposed to a high burden in uncontrolled areas. The majority of our patients are not flea allergic. Much like mosquito bites on humans, the occasional flea bite is usually not more than a nuisance. (Of course, transmission of tapeworms is of some concern.) For these patients, effective flea control is based upon preventing the flea life-cycle from becoming established in the home or yard. Although intensity of treatment may vary because of geography, local flea burden, patient swimming or bathing, and owner preference -- flea control on normal animals typically requires only one product. For most animals, an effective adulticide will be sufficient. If no adult survives long enough to reproduce, the goal has been met. For pampered animals, or animals in areas with few

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Wednesday, March 3, 2010 Thursday, March 4, 2010 Philadelphia, Pennsylvania

fleas, a juvenile control agent may be preferred by owners. Adults may survive short-term, but since they almost never leave the host, the rest of the family is unlikely to suffer. Since any eggs will never transform into adults, again the goal is met. The most common cause of failure is client compliance. A month can whiz by in the summer, and it only takes a couple of extra weeks of non-coverage for a breeding pair of fleas to become 1,000 breeding pairs. Swimming and bathing can reduce the efficacy of many adulticides. Grey-market products may be out of date, or have traveled in a hot shipping container on a slow boat from Australia; examining the product may help in solving the problem. Also, clients may misunderstand package directions; often they will apply topicals to the hair coat, not the underlying skin, as is required. Careful troubleshooting, considering the above common problems, is important because actual resistance to these modern products is very rare. In the few instances that monthly application of a topical (or oral) adulticide is insufficient (typically in Florida, Louisiana, and other hot, humid areas in N. America), alternating every 2 weeks is usually effective. I will often give Comfortis on the first of the month and Revolution on the 15th (and it gets heartworms, too.) Flea-allergic patients must be addressed differently. For these patients, any significant flea exposure will be followed by severe pruritus, hair loss, secondary infections, and perhaps worse. The goal for managing these patients is complete avoidance of flea contact. Obviously, any ongoing life-cycle in the household must be met with speedy and overwhelming eradication. Often, a professional exterminator will be able to effect the most rapid reduction in flea numbers. If clients wish to attempt self-management, the use of both an effective adulticide (deltamethrin, e.g.) and, most importantly, an insect growth regulator (s-methoprene [Precor, others] or pyriproxyfen [Nylar]) to rapidly inhibit juvenile development is necessary The suspected flea-allergic patient must be put on a "flea vacation." This is the use of an adulticide with sufficient dose and frequency that any adult arriving on the patient will be killed very rapidly. From a purely legal point of view, this can be problematic. Many of the most effective products are not FDA drugs, but EPA chemicals; any off-label use of the EPA regulated products is illegal. Although it is unlikely that a veterinarian-recommended medical use will be actively prosecuted, you should remain aware of the possibilities of civil and/or criminal penalties and make your recommendations accordingly. All in-contact animals must have active flea control...not just the allergic patient. This will include, preferably, an adulticide AND a juvenile control agent. When (if?) significant infestations/breeding populations are controlled, reduction to basic levels of flea control may be acceptable for the in-contact animals. However, clients will have to maintain high levels of watchfulness, as reinfestation will likely be associated with significant morbidity in the allergic patient. Here are a few scenarios of suspected flea allergies, and reasonable choices for the first "diagnostic" stage of treatment. All assume environmental control by a professional exterminator (or at the very least, a very diligent client,) and necessary adjunctive antibiotic and antipruritic medication: Four year old F/S domestic shorthair with miliary dermatitis, alopecia, active fleas on exam: Lufenuron now, monthly; Advantage now and every week for 4 weeks. Any adulticide on in-contact animals monthly. Two year old M/C yellow Labrador, with caudodorsal alopecia, hotspots, and flea dirt. Patient swims 3-4 times per week. Comfortis now, Frontline Plus in two weeks, continue to alternate q2wks. Any adulticide on in-contact animals. Three year old F/S long-haired Dachshund, alopecia and pruritus globally, owner refuses any spot-on "chemicals." Lufenuron now, monthly; plus Capstar q48 hours. Comfortis to in-contact animals. Once a diagnosis of FAD is made (patient resolves durably on 100% flea control), an overall, long-range plan should be made with the client. This should include veterinary flea control planning for the allergic animals as well as any other animals in the house, combined therapy if heartworm control is necessary, regular application of IGRs in the environment, and risk reduction when possible.

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TICK CONTROL

Ticks are much more difficult to control than fleas. Because of their complicated life cycle ­ much of which occurs in nondomestic species ­ veterinary acaricides are typically only useful against feeding stages while the tick is present on the domestic host. Furthermore, IGRs are not effective against the eggs or juvenile stages of ticks. Veterinary tick control agents are, therefore, limited to topical and systemic molecules which repel or kill ticks quickly enough (hopefully) to reduce blood consumption and inhibit the transmission of tick-borne disease. Rhipicephalus sanguineus is a partial exception to this, in that its life cycle can be completed entirely indoors with only a single host. Excellent adulticidal control can eventually control an indoor-only infestation of ticks...theoretically. However, most R. sanguineus problems are, like all parasite control issues, best dealt with through integrated management techniques, including premise application of acaricides. It is very important to understand that no agent provides 100% tick control. While published data make it clear that approved agents greatly reduce the risk of tick-borne disease, animals in tick-infested areas will not typically be tick-free 100% of the time. Because of this, owner surveillance is essential. In fact, for animals which are rarely in high-burden areas, owner surveillance and manual removal may be the simplest and most cost-effective control method. In areas with significant tick burden, for patients that travel or work in these areas, or for patients with occasional tick problems that concurrently need flea control, choose an agent which provides reasonable adult kill. Many currently available products are listed on your Flea Control sheet. As usual, tailoring the control regimen to owner and animal habits and preferences is important. K9 Advantix is not a good choice for dogs that swim or bathe frequently, e.g. An excellent product is the Preventic collar for dogs, which is very effective against ticks. Providing three months of control for less than $25, it is very cost-effective as well. However, another agent must be used for fleas, as amitraz has no efficacy against insects. In this form, amitraz is quite safe; however, this collar can be very toxic if chewed or swallowed. I have owners attach the Preventic collar to the inside of the dog's normal nylon or leather collar with 5 or 6 cable ties. This reduces the risk of toxicity from inadvertent ingestion to almost zero...and it prevents contact with cats. Amitraz is highly toxic to cats; never allow a cat to contact a Preventic collar. In dogs with severe tick problems, the use of two agents concurrently is frequently helpful. I typically use a Preventic collar with selamectin or fipronil. Clients must be reminded that, unlike fleas, no agent or combination of agents will guarantee a 100% tick-free pet, and that regular examination and physical removal will likely be necessary.

KILLIN' MITES

Mite ectoparasitosis is common across the domestic species. The diagnosis of this problem has been discussed in your lectures on pruritus and folliculitis. Sarcoptiform mites include Sarcoptes scabei, Psoroptes spp., Chorioptes spp., Otodectes cynotis, and others. The primary clinical sign of infestation with these mites is pruritus...primarily of the ear and face for Otodectes and Notoedres, tail and legs (of horses, goats, etc.) for Psoroptes/Chorioptes, and often globally for Sarcoptes. Hair loss and excoriation will be seen at affected areas, too. Secondary bacterial infections of excoriated areas are common and should be treated as well. For small animals, the treatment of choice for sarcoptiform mite infestation is topical selamectin (Revolution.) The dose used is the same as the standard monthly therapy for flea control and heartworm prevention, and it is labeled for use for Sarcoptes and Otodectes, and should be effective against all the sarcoptiform mites. Standard practice is to give three doses: day 0, day 14, and day 28. However, there is no convincing evidence that this works significantly faster; it may prevent reinfestation. Systemic ivermectin therapy is effective as well. The standard dose is 300 MICROgrams/kg po or subcutaneously on day 0, 14, 28. One dose is likely effective (see selamectin, above.) Ivermectin at this dosage is off-label use, and has been associated with mild side effects in many breeds; severe and life-threatening adverse effects have been noted in many Rough Collies and Shetland Sheep Dogs. For these reasons, I reserve ivermectin for shelter use, or for owners who cannot afford selamectin...and then only in non-herding breeds. The test for MDR1 mutation (which is the primary cause of dangerous ivermectin reactions) is $70...which would be better spent on selamectin.

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110TH PENN ANNUAL CONFERENCE - 2010

Wednesday, March 3, 2010 Thursday, March 4, 2010 Philadelphia, Pennsylvania

There are topical ivermectin and milbemycin solutions intended for use in the ears for Otodectes. These are perfectly acceptable, especially for patients that should not receive topical selamectin; however, make sure that the Revolution contraindication does not apply to other macrocyclic lactones! Other macrocyclic lactones (doramectin, moxidectin) are recommended as well, and there are published reports of efficacy and safety. Check carefully for the latest published information before using these products, and be wary of contraindications. Most small animals without clear evidence of negative heartworm status and/or unbroken heartworm chemoprophylaxis should be demonstrated to be microfilaria-free before treatment with any of the *ectins or milbemycin. Calcium polysulfide (lime sulfur) solution is very effective against sarcoptiform mites, and is often the treatment of choice in herd-health cases. It is very safe in kittens and puppies as well. Because of its rapid onset of effect, and its antibacterial, antifungal, and antipruritic effects, I start severely affected dogs and cats with lime sulfur dips as well as selamectin to reduce the time to resolution, and minimized contagion and zoonosis. Fipronil spray is very useful for Chorioptes in horses, and is likely useful in small and exotic animals as well, if its use is necessary or advantageous. Some sarcoptiform infestations are reportable diseases when found in large animals. If you diagnose acariasis in a large animal, especially a food or fiber species, be sure to contact the appropriate public-health veterinarian if it is caused by a reportable species, or if you are unsure of the diagnosis (mites are hard to distinguish!) Cheyletiella spp. (rabbit fur mite) can cause disease in many species other than rabbits, and diagnosis is straightforward. Any of the agents which are effective against the sarcoptiform mites should work for cheyletiellosis. Demodex gatoi is a strange crossover, and fairly little is known about it. While clearly a demodex mite, it seems to prefer the stratum corneum instead of the follicle. It seems to be horizontally transmissible. It is found it cats, who are typically pruritic (also weird for demodicosis.) The only known effective therapy for D. gatoi is lime sulfur dips, although there is some anecdotal evidence that imidacloprid/moxidectin (Advantage Multi/Advocate) may be effective as well. Because the mites can be hard to find, a fecal flotation may help in diagnosis; otherwise, presumptive diagnosis is based on response to lime sulfur therapy. Demodex canis, Demodex injai, and Demodex cati live in the follicle or sebaceous gland. Patients with these mites typically present with hair loss, dorsal seborrhea, and mild inflammation. Diagnosis is by (deep) skin scraping. The demodectic mites are likely all commensal organisms, existing in low numbers and kept in check by the immune system. Increases in numbers of these are associated with the clinical signs listed above, and are presumed to have an immunological cause, either induced or organic, congenital or acquired. Once large numbers of mites are present, they seem to be able to induce greater immunosuppression, preventing a strong response and allowing the mites to continue to proliferate. Administration of immunosuppressive drugs, particularly glucocorticoids, is associated with the onset and/or rapid worsening of demodicosis. Treatment of demodicosis is often difficult, and the first step is educating owners about the expected cost, risks, duration, and pitfalls of treatment. For our standard protocol for dogs, owners are told to expect 3-6 months of acaricidal treatment, with adjunctive shampoo and antibiotics for at least 45 days of that time. Because of this, remember that the vast majority of juvenile demodex patients self-cure over time. Therapy may certainly be avoided in juvenile-onset localized disease. The only approved treatment for is amitraz solution 20% (Mitaban) diluted to a concentration of 250ppm. The animal's skin and hair is thoroughly saturated with the diluted solution once every two weeks. The major adverse effect of this drug is sedation, which can be marked, as amitraz is an alpha-2 agonist. Sedation is greater in smaller animals presumably because of the increased surface area/mass ratio. Sedation is reversible with yohimbine and atipamezole. Other side effects of this drug include convulsions, ataxia, hyperexcitability, personality change, hypothermia, appetite stimulation, bloat, polyuria, vomition, diarrhea, anorexia, edema, erythema and other varying degrees of skin irritation. Anecdotally, increased concentration (500ppm) and frequency (once weekly) is often required for durable resolution. However, this is also associated with more frequent adverse events. Cats are reportedly very sensitive to amitraz; Mitaban is not approved for use in cats.

PROCEEDINGS: Companion Animal ­ Dermatology

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110TH PENN ANNUAL CONFERENCE - 2010

Wednesday, March 3, 2010 Thursday, March 4, 2010 Philadelphia, Pennsylvania

Because of these myriad unpleasant aspects of the approved therapy, off-label drug use is common in treating demodicosis. Currently, the most common therapy used for demodicosis in dogs is ivermectin, 400 ­ 600 MICROgrams/kg po daily. This treatment is very effective. However, it is 60 to 1500 times the recommended monthly dose for GI deworming and heartworm prophylaxis respectively. Fortunately, the vast majority of dogs tolerate this large amount of ivermectin very well. However, a significant minority will have minor adverse effects, which are usually dose related, and begin to appear a few days to weeks into the treatment regimen. The classic signs of mild ivermectin toxicity begin with mydriasis. Because owners rarely are good observers of pupil changes, the most frequent complaint from owners associated with ivermectin toxicity is ataxia. If either of these is noted, immediate discontinuation of the drug typically allows a return to normal neurological status in a few days. Many patients receiving 600g/kg of ivermectin daily when neurological signs appear will return to normal quickly, and will continue to be normal when therapy is restarted at 400g/kg of ivermectin daily. A few dogs, many of them Rough Collies and Shelties, have mutations of the MDR1 gene which codes for p-glycoprotein. Ivermectin is very neurotoxic, but the blood/brain barrier prevents penetration of the drug, allowing safe use. MDR1 mutants prevent normal function of the BBB. Dogs homozygous for the MDR1 mutation can have severe, life-threatening adverse effects from very low doses of ivermectin...only doses up to 12g/kg once monthly have been clearly demonstrated as safe. Fortunately, there is a convenient inexpensive test for the mutation. Any herding breed, and some others including Australian Shepherd, Australian Shepherd (Mini), Long-haired Whippet, McNab, Silken Windhounds and others (including 1 in 20 mixed breeds) can have the mutation. Checking the genetic status is a good idea for any patient. An alternative, which we frequently use at Penn, is to test any known commonly-affected breed or herding breed cross. All others are instead begun with a very low dosage which is increased slowly to the target therapeutic dose. My current favorite is: 10 g/kg po q24h x3d, then 20 g/kg po q24h x3d, then 40 g/kg po q24h x3d, then 80 g/kg po q24h x3d, then 160 g/kg po q24h x3d, then 320 g/kg po q24h x3d, then {stop after one 320 g/kg dose for Sarcoptes} 600 g/kg po q24h until resolution (q.v.) for follicular/sebaceous demodicosis Owners must be informed of the off-label use of medication, especially those like ivermectin which can have severe adverse effects. The use of milbemycin has been recommended for ivermectin-sensitive breeds (or known MDR1 mutants). Recommended dosages from 0.5 mg/kg/day to 3mg/kg/day have been published. From one report, 0.5mg/kg/day seems like a safe dosage even for homozygous affected dogs. Higher dosages are associated with adverse events; however, they resembled the ataxic reaction seen with high doses of ivermectin after days to weeks, not the immediate life threatening reaction seen in homozygous mutants given ivermectin at high doses. So, while not completely safe, milbemycin is arguably a safer choice. Therapy can be expected to be very expensive, as a 23mg tablet of milbemycin retails for $7.50. Some veterinary schools can purchase the drug at greatly reduced prices, so referral may be a helpful option. Other macrocyclic lactones given orally or parenterally have been reported to be effective; their safety and efficacy have not been completely elucidated. Doramectin 600ug/kg SQ weekly was safe and effective in cats in one study. Topical amitraz/metaflumazone (Promeris) has, in one study financed by the manufacturer, been shown to help control demodex mites, and on this evidence the EPA (which is not very stringent compared to the FDA) has allowed Ft Dodge to advertise efficacy against demodex. Another ad hoc study by an ACVD dermatologist indicated that only 45% of adult-onset dogs were cleared using Promeris after 60 days. While the jury is still out on this product officially, my current take is that is may be worthwhile in a young patient that just needs to be nudged back toward normal skin. I still prefer using ivermectin on true problem cases. Similarly, some have reported that imidacloprid/moxidectin (Advantage Multi) may be similarly useful. The only study is deeply flawed, unblinded, and was performed by the manufacturer. While it may be helpful (and is labeled as such in come countries), I remain skeptical.

PROCEEDINGS: Companion Animal ­ Dermatology

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110TH PENN ANNUAL CONFERENCE - 2010

Wednesday, March 3, 2010 Thursday, March 4, 2010 Philadelphia, Pennsylvania

Because of its safely and efficacy (especially against D. gatoi,) lime sulfur is the recommended treatment for feline demodicosis. Cats are dipped weekly for 4 weeks in a 2% solution. Ivermectin has been used, but, since water-based ivermectin has stability problems, the propylene glycol based solution is the only economically feasible choice for long duration use. Since propylene glycol should be avoided in cats, ivermectin is currently best avoided. The vast majority of demodex patients have secondary bacterial infections (fungal, too, in terriers with D. injai). Antimicrobial therapy targeting staphylococci is an essential element of treating demodex. Even patients without signs of infection will usually develop them as the mites die off....so I typically start oral antibiotics at the same time as ivermectin, and continue for at least six weeks. Of course, if your cytology reveals yeast, treatment for that is important as well. Topical therapy can be important in demodicosis. Especially with the use of Mitaban dips, shampooing can help flush debris and perhaps dead mites from the follicles. Presumably, this allows better penetration of the amitraz solution. For patients with greasy, crusty lesions benzoyl peroxide is the agent of choice. Ethyl lactate shampoo is better for patients with dryer skin. Both of these agents are also helpful in treating the ubiquitous demodex-associated pyoderma As with so much else in dermatology, it is not which therapy to choose that is the Ultimate Question, but when therapy can be discontinued. Because Demodex is hard to kill and induces immunosuppression once established, the goal of therapy is not simply clinical resolution of signs. Stopping at that time is frequently associated with relapses. Rather, our goal is reduction of mite numbers to zero, or at least to undetectable levels. Demodicidal treatment must be monitored regularly. The standard approach is to continue acaricidal therapy until two deep skin scrapings a month apart have revealed no mites...that is, no eggs, juveniles, adults, dead mites,...nothing. Because I typically use a slow increase of ivermectin, and rarely have had a negative scraping after 30 days, I usually perform the first skin scraping 60 days after initiating therapy, and continue to scrape monthly until two consecutive scrapings are completely negative. Unless the owners have an exceptionally large supply (they're cattle farmers, or bought from the Jeffers catalog,) I typically continue the ivermectin until the dispensed amount is gone - just to make extra sure of resolution. Adult-onset demodicosis is often associated with underlying immunosuppressive disease. A complete workup, including screening for endocrinopathy and neoplasia, is indicated for animals over 2 years old with a sudden demodex problem. Direct anti-demodex therapy is unlikely to provide durable resolution unless the underlying medical issue is addressed. Generalized juvenile-onset disease is an indication of an immunological problem. Often these dogs will do well long-term as individuals, but because there is clear heritability of this disorder, they should not be bred. Some dogs with adult-onset demodicosis have no detectable underlying predisposition, yet relapse whenever treatment is withdrawn. In this case, long-term treatment may be necessary. Tapering the dose by reducing the frequency is the best way to do this. Reduce to every other day for one month, then twice weekly for a month, once weekly for a month, etc. I have had patients who maintain well at 600ug/kg po q14days.

CONTROLLING LICE

Lice are fairly rare in small animals. They are more common in exotics, laboratory animals, and large animals. Diagnosis is by finding lice or eggs on examination. It's a good exercise to identify the species of louse; however, most recommended treatments are effective against all lice. Patients usually experience significant pruritus. The expected concomitant hair loss, excoriation, and secondary infections are also seen frequently. In all cases, in-contact animals of the same species (or very closely related ones) should be presumed to be infested as well. Lice can spread through a household, barn, or kennel in just a day or two. There are a few general rules for treating lice in small animals. The topical, non-systemic flea control agents (imidacloprid, fipronil) are excellent choices for all lice. Fipronil spray is particularly convenient and fast-acting. The newer metaflumazone and dinotefuran are likely to be effective as well. Systemic treatment (Revolution, ivermectin, Comfortis) may be less effective (or more slowly effective) against Mallophaga (chewing lice) than Anoplura (sucking lice) because of reduced exposure to agent-containing body fluids. This difference is not well-proven overall, and in general, anything that will cure a bad flea infestation will cure lice. Diligent cleaning of the environment and laundering of bedding should be undertaken repeatedly during treatment.

PROCEEDINGS: Companion Animal ­ Dermatology

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110TH PENN ANNUAL CONFERENCE - 2010

Wednesday, March 3, 2010 Thursday, March 4, 2010 Philadelphia, Pennsylvania

COMPANION ANIMAL: Dermatology

FELINE VIRAL SKIN DISEASES©2010

Alice M. Wolf, DVM, DACVIM, DABVP

Adjunct/Emeritus Professor, College of Veterinary Medicine, Texas A&M University Chief Medical Consultant ­ Veterinary Information Network College Station, TX

FELINE HERPESVIRUS DERMATITIS

Feline herpesvirus1 infection is most noted for causing URI disease and oral ulceration. Latent, persistent infection will occur in about 30% of affected cats. Vaccines do not prevent feline herpesvirus infection nor carriage or intermittent shedding of the virus. Recrudescence of signs or new lesions may occur with stress or concurrent illness. Virus usually resides in the trigeminal ganglion and the distribution of lesions usually follows the distribution pattern of this nerve. Lesions in cats without URI signs are often found on the haired skin of the nasal planum, head, face, or ears. The feet and ventrum may be less commonly affected. Given the pattern of the lesions, the most common DDx for Herpesvirus dermatitis are: mosquito hypersensitivity, EGC, SCC, and allergic or parasitic dermatitis. Microscopic examination of lesions reveals ulceration and nectosis with an inflammatory infiltrate that may contain many eosinophils hence the confusion with EGC and parasitic lesions. The intranuclear inclusion bodies characteristic of herpesvirus may be difficult to find. It may be necessary to send tissue for immunohistochemistry or PCR on tissue biopsy samples. Confirmation of the diagnosis is important because immunosuppressive drugs can worsen this condition. Treatment of herpesvirus dermatitis: L-lysine 250-500 mg PO q12h IFN: 30-30K U PO q24h 250-500K U SQ 3X/wk for 6 weeks Lactoferrin? 350 mg PO q24h Acyclovir: Not effective against FHV1 Famcyclovir: 32 mg (1/4 of 125 mg tablet) PO q12h Imiquimod (Aldara®) 5% cream Topical immunomodulator Apply to lesions q48-72h The prognosis for herpesvirus dermatitis is guarded because the viral infection will persist, lesions are difficult to resolve, and recrudescence is common. FHV1 may be related Idiopathic Ulcerative dermatitis (see below) due to paraesthesia of the nerves in the head and neck that results in self-mutilation.

IDIOPATHIC ULCERATIVE DERMATITIS

May be related to FHV1 as noted above. Attempts at treatment have included: Surgical removal of affected skin Corticosteroids: Depo-Medrol® 20 mg IM q2weeks until healed Behavior modifying drugs Bandaging, topical anti-inflammatory drugs, Soft Paws® nail covers Gabapentin?

PROCEEDINGS: Companion Animal ­ Dermatology

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110TH PENN ANNUAL CONFERENCE - 2010

Wednesday, March 3, 2010 Thursday, March 4, 2010 Philadelphia, Pennsylvania

FELINE CALICIVIRUS

Usually causes an URI syndrome similar to FHV1. Oral ulcerations are common but corneal ulcerations are not seen. Virulent systemic feline calicivirus (VS-FCV) may cause ulceration and skin sloughing associated with the vasculitis seen with this rare but severe form of calicivirus. The face and limbs are most commonly affected with VS-FCV skin lesions. Vaccines do not prevent infection with FCV or VS-FCV, nor prevent chronic carriage. About 25% of FCV-infected cats become chronic carriers and viral shedding is continuous. The most common chronic clinical syndromes are gingivostomatitis and tooth extrusion. A recent report described a postsurgical pustular dermatitis associated with calicivirus in two cats post OHE.

RETROVIRUS-ASSOCIATED DERMATITIS

Unique FeLV dermatitis FeLV can directly cause a rare but unique dermatosis usually affecting the head and neck. The condition is a crusting, alopecic, and sometimes pruritic dermatosis. Histologic examination of affected tissue shows a giant-cell inflammatory infiltrate. There is no effective treatment. Cutaneous Horn Cutaneous horns are exuberant, avascular growths of keratin. They are often asymptomatic and are discovered by owners or on routine veterinary examinations. The footpads/feet are most commonly involved. Lesions may occur on the ears, particularly in association with dermal squamous cell carcinoma (SCC). FeLV-infection may be present in affected cats. Treatment includes periodic trimming of growths to prevent interference with mobility. If the horns are painful and growing from the pads, excision of the base of the lesions may be needed to prevent recurrence. If the lesions are associated with SCC, the neoplastic lesions should be excised, or otherwise managed. Feline Immunodeficiency Virus (FIV) A non-pruritic, generalized, papulocrustous eruption with alopecia and scaling, most severe in the head and limbs, has been reported in FIV-infected cats. Histopathologic examination of the skin demonstrates hydropic interface dermatitis with occasional giant keratinocytes. No treatment benefited the cats. A severe form of mucinous degenerative mural folliculitis has also been reported in cats infected with FIV. No treatment has been reported to be effective. However, skin disease found in FIV-infected cats is often a secondary problem (fungal, bacterial, parasitic) and many of these conditions are treatable. Remember your routine dermatologic diagnostic tools including skin scrapings, cytologic examination, Wood's light examination and fungal culture, bacterial culture, and biopsy.

PAPILLOMAVIRUS

There are several dermatologic syndromes associated with feline papillomavirus infection. Cats do not typically develop oral warts as do dogs. Bowen's Disease Bowen's disease (multicentric SCC in situ) occurs most commonly in middle-aged to older cats. The lesions appear as elevated, irregular plaques occurring in haired, pigmented skin not commonly associated with actinic (solar) dermatitis. The disease does not typically extend beyond the dermis and metastatic lesions have not been reported. Feline Sarcoid Formerly known as fibropapillomatosis, feline sarcoid is very similar in pathogenesis to equine sarcoid. The face, head, and limbs are frequently affected. Treatment for both conditions is similar. Surgical removal is the recommended approach to treatment and lasers are very effective for this. For Bowen's disease topical 5-FU (caution! in cats) and isotretinoin. Other reported therapies include topical Imiquimod cream and radiation therapy.

PROCEEDINGS: Companion Animal ­ Dermatology

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110TH PENN ANNUAL CONFERENCE - 2010

Wednesday, March 3, 2010 Thursday, March 4, 2010 Philadelphia, Pennsylvania

CATPOX (COWPOX)

Catpox is an orthopoxvirus whose primary host is cattle. This condition occurs primarily in the UK and EU. The reservoir of infection is the small rodent population mostly voles and mice. Cats become accidently infected due to their hunting activities. There is a primary lesion at the site of viral inoculation. Secondary lesions appear in 4-16 days and usually involve the head, neck, forelimbs, and paws, areas most subject to bites and scratches from their rodent prey. The diagnosis is made by histopathology and these nodular lesions must be distinguished from much more common nodular dermatoses caused by fungi, bacteria, or neoplastic disease. There is no specific treatment but most cats will spontaneously recover in 3-4 weeks. This is a potential zoonosis.

PROCEEDINGS: Companion Animal ­ Dermatology

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110TH PENN ANNUAL CONFERENCE - 2010

Wednesday, March 3, 2010 Thursday, March 4, 2010 Philadelphia, Pennsylvania

COMPANION ANIMAL: Renal

EVIDENCE-BASED MICROALBUMINURIA TESTING

Barrak Pressler, DVM, PhD, DACVIM

Assistant Professor, Small Animal Internal Medicine Department of Veterinary Clinical Sciences, Purdue University West Lafayette, IN Conventional urine dipsticks are the standard initial screening test for detection of proteinuria. Urine albumin concentration must be approximately 30 mg/dl or greater to be detected by this method. However, normal urine albumin concentration in dogs and cats is in fact significantly lower than this limit of detection; although there are slight differences between cats and dogs, the upper end of the reference range is approximately 1 mg/dl. The range between these numbers (1 - 30 mg/dl) is referred to as microalbuminuria (MAlb), whereas proteinuria greater than 30 mg/dl is referred to as overt proteinuria. Detection of microalbuminuria may therefore allow earlier diagnosis of pathologically increased urine protein excretion, which can occur with primary glomerular diseases or extra-renal inflammatory diseases that secondarily damage the kidneys. However, just as with overt proteinuria, microalbuminuria may be due to pre-glomerular, glomerular, or postglomerular causes. Further testing for primary or secondary glomerular diseases in patients with microalbuminuria should only occur once preglomerular and post-glomerular causes of proteinuria/albuminuria have been excluded. Pre-glomerular proteinuria may be due to functional (also called physiologic) proteinuria, or overload proteinuria. Functional proteinuria is usually benign, transient, and abates when the underlying cause is corrected. This class of proteinuria is poorly documented in veterinary medicine, but possible causes based on what is known in people include strenuous exercise (although one study in dogs did not support this), seizures, fever, extreme heat or cold, and venous congestion (i.e. congestive heart failure or hepatic fibrosis). Overload proteinuria occurs when the tubular resorptive capacity for certain proteins is exceeded, usually because serum concentrations of these proteins are abnormally increased. Diseases associated with overload proteinuria include Bence Jones proteinuria (light chains of immunoglobulins produced by multiple myeloma and some lymphomas), hemoglobinuria, and myoglobinuria. Post-glomerular proteinuria may be due to ANY cause of hemorrhage or inflammation in the ureters, bladder, urethra, or genital tract. Examples include bacterial infections and urinary tract neoplasia or uroliths, regardless of whether a secondary infection is present.

MICROALBUMINURIA: SIGNIFICANCE IN PEOPLE

There are several diseases in people where there is a strong association between MAlb and poor outcome. MAlb is a very strong prognostic indicator for eventual development of renal failure in diabetic patients. Presence of MAlb is also correlated with cardiovascular disease and mortality in all patients with diabetes mellitus, regardless of the type of diabetes. Successful therapy with ACE-inhibitors and better glycemic control slow the progression of MAlb to overt proteinuria, and decreases the likelihood of eventual azotemia and end-stage renal disease. Other inflammatory diseases associated with MAlb in people include some neoplasms, inflammatory bowel disease, and acute inflammatory conditions such as pancreatitis, myocardial infarction, and surgery. In many of these conditions it appears that the degree of MAlb correlates with the severity of the insult. This correlation is particularly evident in people with lung or breast cancer or lymphoma; in these patients presence and degree of MAlb correlates with histologic subtype, tumor burden, presence of metastatic disease, and prognosis. Interest in the prevalence and significance of microalbuminuria (MAlb) in dogs and cats is derived from these strong ® associations in people and because the feline and canine ERD-HealthScreen test point-of-care assays are available. Although a number of abstracts and papers have been published specifically looking at MAlb, there is still no formal consensus on how to proceed with a given result

MICROALBUMINURIA: TESTING RECOMMENDATIONS IN DOGS AND CATS

Patients that usually DO NOT benefit from MAlb testing, or where MAlb should be delayed until underlying causes are identified and treated: · Patients with pyuria or bacteriuria · Patients with confirmed lower urinary tract disease · Patients with hyperglobulinemia suspected to be monoclonal in nature

PROCEEDINGS: Companion Animal ­ Renal - 64 -

110TH PENN ANNUAL CONFERENCE - 2010

Wednesday, March 3, 2010 Thursday, March 4, 2010 Philadelphia, Pennsylvania

· ·

Patients where the UPC ratio has already been documented to be increased Apparently healthy patients where owners would not be willing to spend money on further diagnostics based on the results of MAlb testing

Patients who may benefit from MAlb testing include: · Patients with renal failure and dipstick proteinuria, but which have normal UPCs · Breeds of dogs with a high prevalence of hereditary glomerular disease (Shar-peis, Soft-coated Wheaten Terriers, etc.) · Patients with diseases known to cause glomerular injury, and where therapy could therefore be considered if MAlb positive but still UPC negative (heartworm disease, ehrlichiosis, etc.) · Patients where occult disease is more likely (such as geriatric dogs and cats) and the owners would be willing to spend money for further diagnostics if the patient is MAlb-positive. Unfortunately once MAlb is diagnosed it is still unclear when or how much further investigation is merited. Animals with positive results should first have UPC ratios performed to quantitate the severity of proteinuria. Breeds known to develop hereditary glomerular diseases should likely be monitored regularly, and if proteinuria/albuminuria worsens then renal ® biopsy or non-specific intervention should be considered. In dogs with unexpected, persistently positive ERD-HealthScreen results it may be advised to screen for glomerular diseases and/or extra-renal inflammatory diseases. No doubt, long-term longitudinal studies evaluating the benefit of these recommendations are still needed. One very important study that still must be performed is determining whether age- and breed-specific reference ranges for MAlb are needed; some breeds appear more likely to have MAlb, particularly when they reach the adult or geriatric age range. Likewise, it is unknown whether therapeutic intervention in dogs with microalbuminuria is of any benefit. However, microalbuminuria and overt albuminuria/proteinuria are likely just different points in a single continuum for many diseases, and thus treating the two differently may likewise be a mistake.

PROCEEDINGS: Companion Animal ­ Renal

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110TH PENN ANNUAL CONFERENCE - 2010

Wednesday, March 3, 2010 Thursday, March 4, 2010 Philadelphia, Pennsylvania

COMPANION ANIMAL: Renal

UPDATE ON NEPHROTIC SYNDROME*

Barrak Pressler, DVM, PhD, DACVIM

Assistant Professor, Small Animal Internal Medicine Department of Veterinary Clinical Sciences, Purdue University West Lafayette, IN Nephrotic syndrome is an uncommon to rare complication of protein-losing nephropathies in dogs and cats. It refers to the concurrent presence of proteinuria, hypoalbuminemia, extravascular accumulation of fluid, and hyperlipidemia, and when present is pathognomonic for glomerular disease. Patients with hypoalbuminemia, proteinuria, and hyperlipidemia but no third-spacing of fluid are occasionally referred to as having `incomplete' or `incipient' nephrotic syndrome. However, because nephrotic syndrome by definition requires the presence of edema, and many patients with severe hypoalbuminemia will not develop extravascular fluid accumulation, I do not favor use of these terms.

EMPIDEMIOLOGY

The relative prevalence and causes of nephrotic syndrome in dogs or cats with glomerular disease are unknown. Retrospective studies of dogs with glomerular disease have reported 5.8 to 37.5% of patients are diagnosed with nephrotic syndrome at the time of initial presentation to referral institutions. However, the true prevalence of this complication is likely less than 10%, considering that patients with nephrotic syndrome are more likely to be referred than those with asymptomatic proteinuria. In cats nephrotic syndrome is more likely at the time of diagnosis of glomerular disease, likely due to the high prevalence of membranous glomerulopathy with massive proteinuria in cats with glomerular disease. Nephrotic syndrome in people is more likely in patients with glomerular diseases associated with large amounts of urine albumin loss. Adults with primary glomerular diseases and nephrotic syndrome are most likely to have membranous glomerulopathy. Secondary glomerular diseases, including amyloidosis and diabetic glomerulosclerosis, increase in prevalence in geriatric patients. Pediatric patients with nephrotic syndrome are most commonly diagnosed with minimal change disease. Associations between specific glomerular diseases and development of nephrotic syndrome have not been systematically examined in dogs or cats; however, nephrotic syndrome appears to be more common in dogs and cats with membranous glomerulopathy or dogs with amyloidosis. Nevertheless, any glomerular disease may result in nephrotic syndrome in dogs or cats, including secondary causes of glomerular disease such as drugs, infectious agents, or immunemediated diseases.

CLINICAL PRESENTATION

Patients with nephrotic syndrome most commonly present for abdominal distention secondary to ascites, and in order to be clinically apparent the volume of accumulated abdominal fluid is usually large. However it is not uncommon for patients who are diagnosed with protein-losing nephropathies in the absence of overt ascites to have some degree of sub-clinical abdominal fluid accumulation evident when diagnostic imaging is performed. Many patients also have pitting subcutaneous edema, particularly in the extremities and ventral abdomen, thorax, and neck. Fluid less commonly accumulates in the pleural and pericardial spaces, and dyspnea or tamponade are very rare. The extravasated fluid is usually a pure transudate (total nucleated cell count less than 1000 cells/ul; total protein concentration less than 1.0 g/dl). All patients with significant proteinuria are at increased risk of thromboembolic complications. However, human patients with nephrotic syndrome are at increased risk of thromboembolism as compared to those with asymptomatic proteinuria. This increased prevalence may be due to vascular stasis and/or reduced rate of blood flow due to hypovolemia and reduced activity levels in affected patients. Limited retrospective studies in dogs with glomerular disease suggest that risk of thromboembolism is not linearly associated with severity of proteinuria, but relationship to nephrotic syndrome in particular has not been examined. Sites of thrombosis in dogs reported by others or encountered by this author include the splenic, hepatic, intestinal and other mesenteric veins, pulmonary vasculature, and the renal and adrenal artery and vein. Although people with nephrotic syndrome are at increased risk of coronary artery disease, secondary infections, and acute renal failure, these have not been recognized as occurring more frequently in veterinary patients with nephrotic syndrome versus those with asymptomatic proteinuria.

PROCEEDINGS: Companion Animal ­ Renal

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110TH PENN ANNUAL CONFERENCE - 2010

Wednesday, March 3, 2010 Thursday, March 4, 2010 Philadelphia, Pennsylvania

PATHOPHYSIOLOGY

Nephrotic syndrome may be solely due to massive urinary loss of albumin and other proteins, with third spacing of fluid and hyperlipidemia being natural pathophysiologic consequences of decreased plasma oncotic pressure. Conversely, growing evidence in people and animal models suggests that these latter components of nephrotic syndrome may only be partially related to hypoalbuminemia, and instead may result from independent pathologic processes that occur concurrently with glomerular damage. Proteinuria and hypoalbuminemia: Hypoalbuminemia in patients with nephrotic syndrome is a direct consequence of proteinuria. In people, `nephrotic range' proteinuria refers to urine protein loss greater than 3 g/24 hr/1.73 m2 (in adults), and identifies patients at increased risk for development of nephrotic syndrome. A similar value has not been established in dogs and cats, and clinically, the amount of albumin loss that must be present for third-spacing of fluid to develop in dogs or cats is highly variable. Dogs and cats with severe hypoalbuminemia are commonly encountered that have no or minimal amounts of ascites present, and conversely occasional patients are evaluated with only modest decreases in serum albumin but nevertheless clinically obvious third-spacing of fluids. Retrospective studies of dogs with glomerular disease have not specifically examined serum albumin or urine protein excretion in nephrotic versus non-nephrotic dogs, but dogs with serum albumin concentrations greater than 1.5 g/dl or urine protein:creatinine ratios less than 10.0 are not consistently reported to have third-spacing of fluid. Extravascular fluid accumulation: Hypoalbuminemia is necessary for third-spacing of fluid to occur, but the pathogenesis of extravascular fluid accumulation is more complex than simply due to a drop in plasma oncotic pressure. Under homeostatic conditions edema is usually prevented by re-uptake of fluid in the distal capillaries and the lymphatic circulation. Hypoalbuminemia results in a decrease in plasma oncotic pressure and thus initially favors greater net outward flow of fluid. However, albumin rapidly equilibrates between the vascular and interstitial spaces, and a given reduction in plasma albumin concentration should result in a near-identical decrease in interstitial albumin concentration. Additionally, rodents and dogs with severe, induced hypoalbuminemia fail to develop edema following fluid challenge despite a significant reduction in plasma oncotic pressure. Several hypotheses exist as to metabolic derangements which are responsible for edema formation in patients with nephrotic syndrome. The `underfill' hypothesis argues that the initial decrease in plasma oncotic pressure results in upregulation of the renin-angiotensin-aldosterone system due to the initial increase in fluid extravasation and secondary decrease in circulating blood volume. Increased sodium retention therefore maintains near-normal intravascular hydrostatic pressure which is not matched by an increase in interstitial hydrostatic pressure, and edema forms. Alternatively, the `overfill' hypothesis proposes a primary nephron defect that prevents adequate sodium excretion. Sodium avidity secondarily results in increased intravascular volume, a rise in hydrostatic pressure, and ultimately fluid extravasation. Hypertension would be expected in these patients, and this indeed occurs in human adults and many veterinary patients with glomerular disease with or without nephrotic syndrome. Finally, some evidence suggests that an unidentified `permeability factor,' may directly alter vascular and glomerular permeability and be the cause of edema in nephrotic syndrome. Immunosuppressive therapy in people significantly reduces edema formation with a disproportionately milder reduction in proteinuria, as does plasmapheresis. Relative percentage of various peripheral circulating T-cell subsets and types and amounts of cytokines produced vary in patients with nephrotic syndrome at the time of diagnosis versus time of remission, arguing that some immune dysregulation accompanies disease. Plasma from human patients with some forms of glomerular disease induces proteinuria in rats following intraperitoneal injection, and increases permeability of isolated glomeruli. These studies are of course complicated by the necessary assumption that all nephrotic syndromes have the same pathogenesis; likewise, veterinarians should be cautious in assuming that nephrotic syndrome in veterinary patients has a similar pathogenesis as in people. Hyperlipidemia: Although cholesterol is the only lipid routinely measured in most dogs and cats with nephrotic syndrome, human patients and animal models have both quantitative and qualitative abnormalities in serum lipoprotein profiles. These include an increase in serum total, very low-, low-, and intermediate-density lipoprotein cholesterol, serum triglycerides, and chylomicrons, most of which are inversely proportional to the severity of hypoalbuminemia. A significant correlation between serum cholesterol and albumin has not been found in dogs with glomerular disease in general, but patients with nephrotic syndrome have not been specifically studied. Increases in cholesterol and triglycerides are due to both up-regulated activity of enzymes in their synthesis pathways as well as reduced catabolism.

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TREATMENT

Removal of fluid is recommended only when patients are in obvious discomfort or presence of fluid may be life-threatening. Indications for abdominocentesis generally include dyspnea due to impaired contraction of the diaphragm during inspiration, reduced appetite, or markedly decreased activity levels. A less common indication for removal of ascites in dogs and cats is severe hypertension, which anecdotally may be aggravated by large volumes of ascites. Routine removal of large volumes of fluid should be avoided as this may cause further up-regulation of the renin-angiotensin-aldosterone axis due to hypovolemia following increased extravasation of fluid to replace the removed fluid. Repeated removal of fluid and secondary intravascular underfilling and acidosis may result in hyponatremia and hyperkalemia. Diuretic therapy is usually initiated in veterinary patients with nephrotic syndrome and clinical signs severe enough to merit fluid removal. The dose should be adjusted to minimize fluid accumulation until anti-proteinuric or disease-specific therapy is sufficient to minimize albumin loss; the goal should not be to completely stop fluid extravasation, as the diuretic doses typically required for this outcome lead to hypovolemia and electrolyte abnormalities. Spironolactone, an aldosterone antagonist, may be more effective than loop diuretics in dogs, and minimizes the likelihood of electrolyte abnormalities. Patients that require chronic diuretic therapy may respond best to spironolactone monotherapy or a sub-maximal dose of furosemide in conjunction with standard dosing of spironolactone. Intravenous fluid therapy in patients with nephrotic syndrome is occasionally required when hypovolemia is present or acute renal failure is suspected. Low-sodium isotonic crystalloids or synthetic colloids (which are standardly supplied in 0.9% sodium chloride) are most appropriate. Hypoalbuminemic patients have metabolic alkalosis, and thus 0.9% or 0.45% sodium chloride is more appropriate than alternative buffered solutions. Although in theory a low sodium fluid should reduce the likelihood of iatrogenic `overfill,' patients with nephrotic syndrome are sufficiently sodium avid that decreasing the rate of fluid administration is likely more critical to avoid overhydration and worsening fluid extravasation than the sodium concentration. Anticoagulant therapy in people and veterinary patients with glomerular disease is usually initiated once serum albumin decreases below 2.0-2.5 g/dl or urine albumin loss is greater than 10 g/24 hrs. Aspirin is used most commonly in dogs and cats in order to minimize spontaneous platelet aggregation. Because of the association between hyperlipidemia and coronary artery occlusion by atherosclerotic plaques in people with nephrotic syndrome, treatment with HMG-CoA reductase inhibitors (i.e. `statins') is oftentimes recommended. Fortunately there are no documented consequences directly attributed to hyperlipidemia in dogs or cats with nephrotic syndrome. As a result, other than non-specific therapy with a commercial renal-formulated that includes an appropriately modified polyunsaturated fatty acid ratio, no specific lipid-lowering drugs are recommended. Nephrotic syndrome in people is commonly treated with immunosuppressive drugs, as the most common underlying diseases (membranous glomerulopathy and minimal change disease) are frequently steroid-responsive. Unfortunately, prednisone or cyclosporine in dogs with glomerular disease in general have only provided evidence of worsened or at best unaltered prognosis.

PROGNOSIS

Whether or not dogs or cats with nephrotic syndrome have a poorer prognosis than those with asymptomatic proteinuria is unclear. Short-term prognosis is likely poorer because owners frequently balk at the expense associated with diagnostic evaluation of glomerular disease, the perceived poorer quality of life in patients with nephrotic syndrome, and the frequent lack of specific therapy that can be offered for the underlying disease. Whether long-term prognosis (defined as time from diagnosis until development of azotemia, time until development of uremic crisis, or time until renal-related death) in dogs or cats with glomerular disease is affected by presence of nephrotic syndrome is completely unknown. *These proceedings are excerpted and modified from the chapter `Nephrotic Syndrome,' in the forthcoming textbook, Nephrology and Urology of Small Animals, eds. J. Bartges and D. Polzin, Wiley-Blackwell, Ames IA.

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COMPANION ANIMAL: Renal

TREATMENT OF GLOMERULAR DISEASE: BEYOND ACE-INHIBITORS

Barrak Pressler, DVM, PhD, DACVIM

Assistant Professor, Small Animal Internal Medicine Department of Veterinary Clinical Sciences, Purdue University West Lafayette, IN

The reasons why proteinuria is directly associated with progression of renal disease are unknown, but are likely multifactorial. As the proximal convoluted cells increase phagocytosis of inappropriately filtered protein, they may be subject to relative hypoxia due to the increased workload, and oxygen radicals and heavy metals may accumulate within tubular epithelial cells during protein catabolism. In addition, non-reabsorbed protein may obstruct renal tubules, leading to individual-nephron obstructive uropathy. Finally, some proteins such as complement and immunoglobulins may activate the immune system within the renal tubules. Based on the known association between proteinuria and poor clinical outcome, early intervention to decrease proteinuria is an important part of the management of dogs with kidney disease. The current recommendations by an ACVIM consensus panel of nephrologists with a specific interest in glomerular disease and proteinuria are that non-azotemic dogs and cats with urine protein:creatinine (UPC) ratios >2.0 merit protein-reducing interventions regardless of whether or not further diagnostic testing is performed. Treatment should be instituted in azotemic dogs even earlier, when the UPC ratio is greater than 0.5. Intervention is recommended in azotemic cats when the UPC ratio is greater than 0.4. The first step in the diagnosis and treatment of proteinuria is to determine if the increased protein is of pre-glomerular, glomerular, or post-glomerular origin. Pre-glomerular or post-glomerular proteinuria does not require specific intervention to reduce protein excretion. If glomerular proteinuria is diagnosed then the most important therapy is the identification and treatment of any specific infectious or inflammatory diseases that may be causing the underlying renal dysfunction. Treatment of concurrent diseases may prevent, slow, or reverse renal disease, whereas missing these concurrent conditions will likely not prevent progression to renal failure or nephrotic syndrome even if generalized therapy for proteinuria is begun.

GENERAL THERAPY FOR PROTEINURIA

Angiotensin-converting enzyme inhibitors Reduction of urine protein excretion by inhibition of angiotensin-converting enzyme (ACE) activity is the mainstay treatment for proteinuria of glomerular origin in dogs and cats. The best characterized benefit of these drugs is the reduction of protein excretion into the urine. Preferential vasodilation of the afferent renal areteriole is one of the compensatory mechanisms whereby individual nephron GFR increases during chronic renal failure. Reduction of systemic angiotensin II activation by inhibition of ACE results in further vasodilation, but in particular the preferential dilation of the efferent arterioles occurs over that of the afferent. This results in reduced intraglomerular hydrostatic pressure through a reduction in glomerular `afterload.' The net effect is a reduction in the amount of filtrate (including protein) that passes into Bowman's space and eventually into the urine. Although the reduction of intraglomerular hydrostatic pressure is the best characterized benefit of ACE inhibitors, additional benefits to this drug class have been identified. ACE inhibitors reduce mesangial cell hypertrophy in dogs with experimentally-induced glomerular disease either as an independent benefit of therapy or secondary to reducing intraglomerular hypertension. There is a general reduction in systemic arterial hypertension both via reduced angiotensin II concentration and reduced water and sodium retention (via reduced renin activation). Other mechanisms of vasodilation and modulation of inflammation includes prevention of bradykinin degradation, which promotes nitric oxide and prostacyclin production and further induces glomerular efferent arteriolar dilation. Which one(s) of these benefits is most critical for prolonging time until uremic crises or until death in dogs is unknown. Enalapril is the most commonly used ACE-inhibitor (0.5 mg/kg q12-24h). A maximal reduction in proteinuria is desirable, so beginning with the maximum dose is recommended in non-azotemic patients. Adverse effects with this drug are

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uncommon. However because ACE-inhibitors reduce blood flow into the vasa recta, when treating severely azotemic animals (I worry when creatinine is >3.5) I begin with the longer dosing interval (q24h), recheck creatinine after four to seven days, and then increase to q12h if there has been no worsening in serum creatinine concentration. Other reported side-effects (which are definitely problematic in people) include hyperkalemia and anorexia due to gastrointestinal disturbances. In both cases withdrawal followed by restarting at lower doses can be attempted. In people, ACE inhibitor therapy is a relative-to-absolute contraindication for administration of NSAIDs because of the cumulative reduction in renal medullary blood flow; it is likely wise to avoid the combination of these drugs in veterinary patients as well. Other ACE-inhibitors, including benazapril, lisinopril, captopril, ramipril, and quinapril are commercially available. There are very few studies directly comparing these drugs in the experimental setting, and none in animals with naturally-occurring disease. All of these drugs reach therapeutic serum concentrations with appropriate half-lives in healthy dogs with the exception of captopril. Benazapril is an attractive alternative to enalapril in veterinary patients because it in theory may be administered q24h with the same apparent effect as q12h enalapril, and because in experimental studies dogs with kidney disease did not require the same dosage adjustments that enalapril may require. However, there are several studies which provide indirect evidence that not all ACE-inhibitors can be relied upon to have equivalent effects in dogs with proteinlosing nephropathies. For example, quinapril is more effective than enalapril in reducing severity of echocardiographic variables in Cavalier King Charles Spaniels with asymptomatic mitral regurgitation, serum enalaprilat (the active metabolite of enalapril) concentration increases in dogs with sub-normal GFR, whereas benazeprilat does not, and captopril does not reduce serum ACE activity in healthy dogs as well as other ACE inhibitors. Therefore, I prefer enalapril over benazapril in dogs because the only study on the effects of ACE-inhibitors in dogs with naturally-occurring glomerular disease studied the benefits of enalapril...and why fool around with something that's definitely been shown to work? Studies of cats with chronic kidney disease indicate that presence and severity of proteinuria may also associated with decreased long-term survival. Therefore treatment with ACE-inhibitors to reduce protein excretion may be beneficial (although results are conflicting). I choose to treat cats with chronic kidney disease and proteinuria with benazapril (0.5-1.0 mg/kg q24h), again, because the only efficacy study on ACE-inhibitors for reduction of proteinuria in cats was performed with this drug rather than enalapril. Other anti-proteinuric drugs Angiotensein receptor blockers Although ACE-inhibitors are effective at reducing the severity of proteinuria in most dogs and cats with protein-losing nephropathies, it is not uncommon for the urine protein:creatinine ratio to still be above reference range in affected dogs even when the maximal drug dose is used. In order to further decrease proteinuria, some veterininary nephrologists have begun to use angiotensin II receptor blockers (ARBs, e.g. losartan) in those cases of severe proteinuria where ACE-inhibitors alone are insufficient. The reason why this double-pronged approach makes intuitive sense is because the little angiotensin II that is activated can be blocked by the use of ARBs. In addition, ARBs, and losartan in particular, may reduce the risk of thromboembolism in patients with severe proteinuria by interfering with angiotensin-II-mediate platelet activation. However, whether or not concurrent use of ACE-inhibitors and ARBs truly offers any advantage beyond reduction of proteinuria is unclear. In people, ARBs and ACE-inhibitors are both used as first-line therapy for reduction of proteinuria; both classes of drugs have been documented to reduce UPC, reduce the rate of decline of renal function, and improve longterm outcome. However, concurrent use of a drug from each class, although further reducing UPC, does not seem to likewise further slow renal functional deterioration. In fact, the two drugs together have a higher risk of hyperkalemia (which may be severe), and in some studies the combination have actually lead to worsened outcome for patients with some glomerular diseases, particularly in the presence of concurrent cardiovascular disease. Equivalent studies have not been performed in dogs as of yet, and as such ARBs are not advocated as first-line therapy, and it is unknown if combination treatment worsens, improves, or does not change prognosis. When used losartan (Cozaar®) is recommended at a starting dose of 0.5 mg/kg q12h. If creatinine has not increased more than approximately 30% after 4-7 days and the UPC is still increased, then the dose is increased step-wise to 1-2 mg/kg q12h, again rechecking serum creatinine and UPC after each dose adjustment. Anecdotally gastrointestinal side-effects have been reported. Aldosterone receptor antagonists Despite the use of ACE-inhibitors and ARBs, serum aldosterone eventually increases almost to pre-treatment concentrations in people with protein-losing nephropathies. This phenomenon, termed `aldosterone escape,' is likely due

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to positive feedback loops increasing angiotensin I synthesis and release, and ACE activity, in response to the relative angiotensin II deficiency induced by therapy. In addition to those direct effects described above on systemic and glomerular vascular tone, angiotensin II induces aldosterone synthesis and release from the zona glomerulosa of the adrenals. Aldosterone promotes sodium and water retention, increasing glomerular and systemic preload, and is itself a pro-fibrotic agent. Therefore, spironolactone has been advocated by some human nephrologists to combat aldosterone escape, particularly in those patients who require chronic anti-proteinuric therapy. There is no published evidence on the use of aldosterone antagonists in non-nephrotic veterinary patients, and this author is not aware of any anecdotal evidence. Dietary therapy Reduction in dietary protein has been shown to reduce urinary protein loss in experimental models of glomerular disease, including in hereditary canine nephritis. Unfortunately whether this dietary therapy results in improved long-term prognosis and whether the reduction in proteinuria also occurs with naturally-occurring glomerular diseases is unknown. Preliminary results from one study did not show reduction in proteinuria in dogs receiving a protein-restricted diet, but the small number of dogs studied and lack of histologic subclassification makes interpretation of the results difficult. Most nephrologists routinely recommend dietary therapy for patients with glomerular disease, regardless of whether or not they are azotemic. Severely protein-restricted diets likely do not provide increased advantage over the moderately-restricted diets. Commercial `renal diets' are moderately protein restricted, and also have the advantage of sodium restriction and increased omega-3 fatty acid concentration which are theoretically advantageous in dogs with glomerular or tubular renal disease. Immunosuppression Immunosuppression is an inappropriate non-specific treatment for proteinuria, and should only be reserved for specific types of glomerular diseases. For example, prednisone induces mesangial cell proliferation and proteinuria in healthy dogs, and glomerular disease and proteinuria are common in dogs with hyperadrenocorticism. Likewise, cyclosporine is of no clinical or biochemical benefit in dogs with naturally-occurring glomerular diseases. Non-specific immunsuppression is inappropriate in small animals because membranoproliferative glomerulonephritis is the most common histologic subtypes of glomerular disease. This disease subtype is most likely associated with extrarenal infectious or inflammatory diseases resulting in glomerular immune complex deposition within the glomerulus, and therefore immunosuppresion may worsen the underlying disease and cause more rapid progression of the glomerulonephritis. However, I do treat some cases of primary membranous GN with immunosuppression (initially, prednisone and azathioprine) if there is no evidence of extra-renal inflammatory diseases on thorough work-up, and if there is no or minimal evidence of chronicity or inflammation on renal biopsy. I highly recommend consultation with a nephrologist prior to starting immunosuppression, as subtle clues in the renal biopsy may be missed by many pathologists. Aspirin therapy Although hypoalbuminemia and its consequences (edema, ascites) are the most commonly noted sequelae of severe proteinuria, other proteins of similar charge and similar or smaller size as albumin are also lost in the urine. In particular, dogs with severe hypoalbuminemia should be assumed to be hypercoagulable due to loss of antithrombin III and other anticoagulant proteins. Antithrombin III can be measured by several commercial laboratories, but those studies which have evaluated serum concentrations of this protein in dogs with protein-losing nephropathies have reported a general correlation with serum albumin concentration. As a result, I do not routinely measure antithrombin III unless I clinically suspect thromboembolism despite a normal or only slightly decreased serum albumin concentration. Aspirin (0.5 mg/kg q24h) inhibits platelet aggregation via inhibition of cyclooxygenase, and thus works independent of coagulant protein concentrations. In general, I begin aspirin therapy in dogs with serum albumin concentration less than 2.5 g/dl. Oncotic and diuretic support Occasionally, dogs with severe hypoalbuminemia will present with peripheral edema or ascites. Fluid therapy designed to increase plasma oncotic pressure (synthetic colloids, plasma, or albumin) usually have a transient effect and are unsuitable for long-term support of animals with hypoalbuminemia. I only use oncotic support for those patients who present with life-threatening fluid accumulation that requires immediate intervention, such as patients with pulmonary edema or pericardial effusion. Because of the large volumes of synthetic colloids typically required to raise plasma oncotic pressure back to a range that inhibits fluid extravasation, in these cases I instead use plasma in cats and small dogs, and human albumin and synthetic colloids in large dogs, with the expectation that benefits will fade within 48 hours. Unfortunately,

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there is a high frequency of side-effects in normal dogs receiving human albumin, including immediate and delayed anaphylaxis; therefore this drug should definitely be used with caution, and only when absolutely necessary. Patients with significant edema/ascites may require chronic diuretic administration to prevent discomfort or lifethreatening complications. Furosemide is commonly used because of its wide availability, low cost, and ease of dosing. However spironolactone may actually be preferable because of its potassium-sparing and aldosterone-inhibiting properties, in addition to the anti-proteinuric effects discussed above. Any patient administered diuretics should be closely monitored for dehydration, as patients with glomerular disease are predisposed to development of azotemia through progressive tubular damage; prolonged dehydration may thus cause rapid progression of disease. Specific therapy for treatment of amyloidosis A number of drugs have been recommended for dogs with amyloidosis. Colchicine is the drug of choice for treatment of Shar Peis. Although colchicine is known to interfere with the mitotic spindle and inhibits secretion of serum amyloid A in vitro, its effects have not been fully explained. In people predisposed to developing Familial Mediterranean Fever (FMF), an inherited disease that shares many characteristics with renal amyloidosis of Shar Peis, administration of colchicine is highly successful in preventing amyloid deposition. Some people with early renal disease due to FMF may in fact have reduction or resolution of proteinuria after starting colchicine therapy. Although no long-term reports exist on treatment of Shar Peis with amyloidosis, at least two Shar Peis with liver failure secondary to hepatic amyloidosis had long-term survival with colchicine administration. Based on experience in people with FMF, the ability of this drug to prevent amyloid deposition is independent of its success or failure in decreasing the number of fever episodes. Therefore, if given to Shar Peis, owners should continue administration regardless of whether lameness or fever persist. Dogs receiving colchicine may develop dose-related gastrointestinal side effects. Dimethylsulfoxide (DMSO) has also been advocated for treatment of amyloidosis in people and dogs (80 mg/kg/day divided TID, given as a 10% solution PO or SQ). Although DMSO does cause amyloid fibrils to dissolve in vitro, it is now believed that the beneficial effects may be instead due to the drug's anti-inflammatory effects. Efficacy studies in animals have been conflicting. Most beneficial effects have been documented in experimental non-canine models. Of the few reports of DMSO use in dogs with naturally occurring amyloidosis, one had significant improvement with long-term therapy, two survived for at least 10 months, and nine others had no improvement or DMSO was discontinued soon after initiating therapy due to side-effects. In the first dog, hypoalbuminemia resolved over the course of 12 months; however, two concurrent inflammatory conditions were also successfully treated, making the actual benefit of the DMSO difficult to determine. Unfortunately, this drug can cause local irritation and an unpleasant odor, and administration by owners is difficult. However, because of the lack of alternative drugs for treatment of amyloidosis other than colchicine, DMSO is still occasionally recommended in non-Shar-Pei dogs with amyloidosis, and I will offer it to dedicated or desperate owners.

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COMPANION ANIMAL: Renal

DIAGNOSTIC AND THERAPEUTIC APPROACH TO CRYSTALS VS. STONES

Barrak Pressler, DVM, PhD, DACVIM

Assistant Professor, Small Animal Internal Medicine Department of Veterinary Clinical Sciences, Purdue University West Lafayette, IN

STRUVITE

Crystalluria: Struvite crystalluria occurs in greater than 50% of healthy dogs, including animals without urinary tract infections; these crystals are likewise common in healthy cats. Incidental struvite crystalluria occurs because the mineral components of these crystals (magnesium, ammonia, phosphate) are normally excreted in large amounts into urine, and supersaturation leads to precipitation and crystal formation. Crystalluria in and of itself does not result in clinical signs of lower urinary tract disease. In the absence of clinical signs of lower urinary tract disease, urine culture can be considered in animals with heavy struvite crystalluria and a history of bacterial urinary tract infections and in animals with concurrent diseases that predispose to urinary tract infections. Intervention should be considered when large numbers of crystals are present in a patient with a history of obstruction (because struvite crystals may make up a large component of plugs) or a history of sterile struvite urolithiasis (because crystalluria implies urine supersaturation). Preventative therapy is the same as for urolith prevention (see below). Urolithiasis: Struvite uroliths in dogs are due to bacterial urinary tract infection with urease-producing bacteria in greater than 95% of cases, whereas in cats sterile (i.e. not associated with infection) struvite uroliths are diagnosed more frequently. Struvite urolithiasis primarily occurs in female dogs because of the higher prevalence of bacterial urinary tract infections. Urine is usually (but not always) alkaline, and in many cases sediment examination reveals struvite crystals and/or active urine sediment due to the concurrent infection. Urine culture should result in growth of a urease-producing bacterial species, most commonly Staphylococcus sp. or Proteus sp.; less common urease-producing infections include Klebsiella sp.; Corynebacterium sp.; Enterococcus sp.; and Mycoplasma sp. The presence of a non-urease producing bacterial species usually implies an alternative stone type with secondary infection. Imaging typically reveals radio-opaque uroliths; the size and number may widely vary, although infection-induced nephroliths are frequently `staghorn' in shape. Struvite uroliths can be dissolved with a combination of diet and drugs. Hill's S/D is the only commercial diet verified to be sufficiently low in protein, magnesium, and phosphorus, is acidifying, AND has been proven to dissolve struvite uroliths in a prospective study. Unfortunately, S/D is not a nutritionally complete diet, and therefore should not used as a long-term maintenance diet. In conjunction with dietary dissolution of the urolith, resolution and prevention of urolith recurrence requires identification, treatment, and prevention of concurrent bacterial urinary tract infections. After culture and sensitivity testing of urine, an appropriate antibiotic should be administered until the urolith has been completely dissolved (i.e. well beyond the standard two weeks of antibiotics typically prescribed for treatment of uncomplicated urinary tract infections). After beginning dissolution therapy, patients should be rechecked approximately every 4 weeks. Urinalysis and urine culture should be performed to confirm the continued effectiveness of therapy and owner compliance, and survey radiographs taken to monitor progression of dissolution. Therapy should be continued for 2-4 weeks beyond radiographic resolution of stone. In some cases surgical intervention may be required rather than attempting dissolution, particularly in the presence of severe clinical signs, obstruction, or pyelonephritis. Prevention of recurrence of infection-associated struvite urolithiasis should solely be focused on prevention of bacterial urinary tract infections. Recurrence of uroliths is usually due to incomplete dissolution of stones, and/or persistence of infection, or due to an underlying impairment of the normal urinary tract defense mechanisms, leading to recurrent infections. For sterile struvite uroliths (as occurs in cats and very, very rarely in dogs) no good data exists for any struvite-preventive diet. It may be sufficient to simply switch the diet to anything the patient will readily consume; Hill's W/D or Hill's C/D Multicare are oftentimes recommended as a well-tolerated diet that in theory minimize struvite urolith formation. Canned diets increase water intake, and thus urine production, and may help with uroliths prevention via reducing urine specific gravity and preventing supersaturation with the component minerals.

CALCIUM OXALATE

Crystalluria: Calcium oxalate crystalluria is not an uncommon finding in healthy dogs and cats. However, as with struvite crystalluria, in the vast majority of patients calcium oxalate crystals are idiopathic and do not merit intervention. In rare

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cases calcium oxalate crystalluria may be associated with ethylene glycol ingestion or diseases that cause hypercalcemia or promote calciuria (e.g. hyperparathyroidism). Therefore, continued presence of calcium oxalate crystalluria in patients with other clinical signs of disease, a full minimum database, particularly serum calcium, BUN, and creatinine, should be considered. Intervention in animals with calcium oxalate crystalluria but no uroliths may be considered when large numbers of crystals are present in a breed that is predisposed to urolith formation (see below), and should definitely be instituted in animals with a history of calcium oxalate urolithiasis. Preventative therapy is the same as for urolith prevention. Urolithiasis: The pathogenesis of calcium oxalate urolithiasis is unknown, and may be different or more complex than that of calcium oxalate crystalluria. Calcium oxalate uroliths cannot be dissolved and therefore require more invasive procedures for removal. As such, it should be stressed to owners that management and prevention protocols require strict owner compliance and regular monitoring by a veterinarian. Even with strict adherence to current recommendations, recurrence rates for calcium oxalate uroliths remain high. Predisposed dog breeds include the Miniature Schnauzer, Lhasa Apso, Bichon Frise, Pomeranian, Shih Tzu, Maltese, Miniature Poodle, Yorkshire Terrier, and Chihuahua. In cats, almost 100% of upper urinary tract uroliths are calcium oxalate as well as the majority of lower urinary tract uroliths. Calcium oxalate uroliths are also associated with diseases that increase urinary calcium excretion, particularly hyperadrenocorticism (dogs), hyperparathyroidism (dogs and cats), and idiopathic hypercalcemia (cats). Clinical signs secondary to uroliths, recurrent/persistent infection, partial or total obstruction of the urinary tract, and high risk of obstruction are the most common indications for intervention. Options for removal include surgery, extracorporeal shock wave lithotripsy (ESWL), laser lithotripsy, voiding urohydropropulsion, and catheter-assisted retrieval. ESWL and laser lithotripsy have limited availability and not all patients are candidates, but they are effective and minimally invasive; the main disadvantage is relative cost. Voiding urohydropropulsion and catheter-assisted retrieval are even less invasive procedures and ideal for retrieval of small uroliths. Surgical removal of ureteroliths and nephroliths is more technically demanding and associated with higher morbidity and mortality. Some nephroliths and ureteroliths may not require immediate intervention, and in appropriate patients monitoring or medical therapy to promote voiding and slow a possible increase in size may be considered rather than immediate surgery. Goals for prevention of calcium oxalate urolith formation are reduction in dietary protein content, alkalinization of urine, increase in urine concentration of calcium oxalate inhibitors, decrease in urine specific gravity, and a decrease in dietary calcium and oxalate. Some of the most widely used diets in dogs for prevention of this uroliths type include Hill's U/D, Royal Canin S/O, and Hill's W/D; Hill's U/D has the most anecdotal and published evidence in the veterinary literature. Hill's W/D should be used primarily in patients that cannot tolerate the high fat content of the other diets, such as patients with a history of pancreatitis or hyperlipidemia, and in dog breeds that are predisposed to development of carnitine or taurinedeficient cardiomyopathy; however, if this substitution is made, potassium citrate must be added to modify the urine pH to appropriately alkaline levels. In cats available diets include Hill's C/D Multicare or Royal Canin S/O. Hill's W/D with potassium citrate has also been attempted, particularly in cats with idiopathic hypercalcemia. Alkalinization of urine is recommended because calcium oxalate precipitation is promoted at urine pH lower than 7.0. Potassium citrate is the drug of choice, and Hill's U/D and K/D and Royal Canin S/O have been formulated to alkalinize by addition of this drug. Nevertheless, further potassium citrate supplementation may still be required in some cases. Dogs with hyperkalemia secondary to potassium citrate (rare) can be given sodium bicarbonate instead. Note that alkalinization of urine is difficult to impossible to achieve without a concurrent low protein diet--potassium citrate alone without a change in diet is not recommended as sole therapy. Increased urine concentration of calcium oxalate inhibitors is also primarily accomplished by administration of potassium citrate; citrate is an in vitro inhibitor of crystal formation. Decreased urine specific gravity is desirable as increased urine volume prevents supersaturation with component minerals. This is accomplished by giving a canned diet and a diet low in protein. A decrease in dietary calcium and oxalate theoretically seems to make sense, but it is not recommended to lower these below minimal requirements, and a concurrent decrease in both minerals is likely needed. Other therapies have been recommended as well, but are either unproven or are not used as first-line options. Vitamin B6 increases metabolism of oxalate precursors to glycine instead of oxalate. No controlled studies exist and this drug is not routinely used, but it appears to be relatively harmless. In those cases where optimal therapy fails to prevent calcium oxalate urolith recurrence or persistent calcium oxalate crystalluria, thiazide diuretics (hydrochlorothiazide) should be

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prescribed. These diuretics induce diuresis and also promote calcium reabsorption (therefore decreasing urine calcium concentration).

AMMONIUM URATE / URIC ACID

Crystalluria: Urate crystals may be uric acid, sodium urate, or ammonium urate. Unlike struvite and calcium oxalate, uric acid crystals and uroliths should not be considered normal or incidental findings on urinalysis. Urine supersaturation may occur with impaired hepatic handling of uric acid and ammonia (i.e. in animals with hepatic disease, particularly portosystemic shunts), or in animals with metabolic errors that impair conversion of uric acid to allantoin and/or increase uric acid secretion into urine. Breeds with known increased risk of abnormal urate handling include Dalmatians and English Bulldogs. Asymptomatic urate crystalluria in an atypical breed should be followed by a full minimum data to screen for possible hepatic dysfunction, and a liver challenge test (serum bile acids or ammonia tolerance) if needed. The primary disease should be treated in those animals with confirmed hepatic dysfunction; specific therapy to decrease crystalluria is not always needed. Intervention in patients without hepatic dysfunction (i.e. presumptively due to error of metabolism) and without a history of urolith formation should be considered in males, particularly dogs (females rarely develop urinary tract obstruction secondary to urolithiasis). Intervention should also be considered in young animals; animals greater than 6-8 years of age at the time that urate crystalluria is first diagnosed are less likely to progress from urate crystal formers to urate urolith formers. Therapy for urate crystal prevention is the same as for urolith prevention (see below). Urolithiasis: Urate urolithiasis should be suspected in animals that present with clinical signs of lower urinary tract disease and have radiolucent uroliths identified via contrast radiographs or ultrasonography. Dalmatians and English Bulldogs with radiolucent stones can often safely be assumed to have uroliths due to genetic predisposition; nevertheless remember that hepatic dysfunction can occur in any breed. When urate uroliths are diagnosed in other dog breeds, very young Dalmatians and English Bulldogs, and cats, hepatic function testing should be performed, including a minimum database and liver function challenge testing. The median age of dogs at first episode of urate urolithiasis not associated with hepatic dysfunction is 3.5 years. Urate uroliths can be dissolved by a combination of dietary and drug therapy. Medical therapy should be a last resort in patients with liver dysfunction. If PSS shunt is present, surgical intervention is ideal; uroliths can be removed at the time of surgery via cystotomy, or prior to surgery if small via voiding urohydropropulsion or catheter-assisted retrieval. Additionally, urate uroliths associated with PSS may dissolve spontaneously after correction of the anomalous vessel. In patients with other causes of hepatic dysfunction allopurinol is contraindicated, as this drug requires hepatic activation. If no hepatic dysfunction present, then medical intervention can promote dissolution. A low protein diet (Hill's U/D) should be administered. Complete owner compliance is essential; compliance and effectiveness of this diet can often be confirmed by monitoring urine specific gravity (should be <1.025) and/or serum BUN (should be <10 mg/dl). Concurrent potassium citrate may be required if urine alkalinization is not achieved with U/D alone. Allopurinol (10-15 mg/kg q8-12h) should be administered until complete dissolution. Surgical intervention may be required in cases of severe clinical signs, obstruction, or pyelonephritis Prevention of urate urolith recurrence usually requires correction of underlying disease in dogs with hepatic dysfunction. Long-term therapy with Hill's L/D may delay urolith recurrence, but this is theoretical rather than documented by a controlled study. In dogs with inborn metabolic errors, dietary therapy is used alone initially, followed by concurrent drug therapy only if required. Hill's U/D is recommended in most breeds; the ultra-low protein concentration of this diet decreases precursor availability for urate formation. Hill's K/D is used primarily in patients with concurrent renal disease, or patients that require a low protein diet but are at risk for taurine and/or carnitine-deficient dilated cardiomyopathy (English Bulldogs). In patients where dietary therapy alone fails to prevent urate urolith recurrence, owner compliance should be confirmed. If compliance is determined to not be an issue, then after dissolution of the recurrent uroliths, long-term allopurinol therapy should be instituted.

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110TH PENN ANNUAL CONFERENCE - 2010

Wednesday, March 3, 2010 Thursday, March 4, 2010 Philadelphia, Pennsylvania

COMPANION ANIMAL: Renal

STAGED MANAGEMENT OF CHRONIC KIDNEY DISEASE

Scott A. Brown, VMD, PhD, DACVIM

Department Head, Small Animal Medicine and Surgery University of Georgia, College of Veterinary Medicine Winterville, GA

INTRODUCTION

Any disease that affects the kidney is likely to alter both renal structure and function. It is the adequacy of renal function, however, that dictates the impact of this disease on the patient. While the kidney has many biological functions of importance to an animal, the most basic and central renal function is filtration; its measurement yields the glomerular filtration rate (GFR), which serves as the "gold standard" for assessment of the kidney in dogs and cats. In the research laboratory, renal filtration is assessed as urinary clearance of marker substances, such as inulin or creatinine. In clinical patients, urinary clearance tests are generally not practical and the measurement of the disappearance from plasma of renally cleared marker substances such as creatinine, inulin, iohexol, or diethylenetriaminepenta-acetic acid (DTPA), 1-3,4 Labato, 1991 #956 Nonetheless, in clinical following intravenous administration, can provide an approximation of GFR as well. patients GFR is still usually assessed by the measurement of plasma concentrations of creatinine and/or urea. It is generally fair to assume that the level of most renal functions parallel changes in GFR in a clinical patient. The accumulation of nonprotein nitrogenous materials, such as creatinine and urea, is referred to as azotemia, which may be classified as prerenal, renal, postrenal, or of mixed origin. Prerenal azotemia occurs whenever mean systemic arterial blood pressure declines dramatically to values below 60 mmHg and/or when dehydration causes an elevation in plasma protein concentration. Conditions that commonly lead to the development of prerenal azotemia include dehydration, congestive heart failure, and shock. Prerenal azotemia generally resolves with appropriate treatment as dogs and cats are resistant to adverse renal effects of hypoperfusion of the kidney. Renal azotemia refers to a dramatic fall in GFR produced by an intrarenal process (i.e., primary kidney disease), occurring secondary to acute or chronic kidney disease (CKD). Postrenal azotemia occurs when there is a disruption of the integrity of the urinary tract (e.g., bladder rupture) or an obstruction to urine outflow (e.g., urethral or bilateral ureteral obstruction). Uremia or the uremic syndrome refers to that constellation of clinical signs that accompanies severe azotemia.

CHRONIC KIDNEY DISEASE (CKD)

Chronic kidney disease (CKD) refers to a disease process in which there is a loss of functional renal tissue due to a prolonged (generally >2 months in duration), usually progressive, process. A CKD will generally produce dramatic changes in renal structure as well, although there is only a loose and imprecise correlation between structural and functional changes in this organ. This is partly because of the tremendous renal functional reserve as animals can survive for long periods with only a small fraction of initial renal tissue, perhaps 5-8% in dogs and cats. Thus, a CKD often smolders for many months or years before it becomes clinically apparent. Most CKD are not reversible and once acquired a CKD rarely resolves. Although congenital disease causes a transient increase in incidence of CKD in animals <3 yr old, the prevalence of CKD increases with advancing age from 5-6 years 5,6 A reasonable upward. In geriatric populations at referral institutions, CKD affects up to 10% of dogs and 35% of cats. estimate of the prevalence of CKD in the general small animal population is 1-3% of cats and 0.5 ­ 1.5% of dogs. CKD in dogs and cats generally progresses along a continuum from an initial nonazotemic stage to end-stage uremia. As veterinarians, we are obligated to address the specific problems and patient needs that characterize the animal's disease, and this varies from stage to stage. The International Renal Interest Society has proposed a classification system for CKD which facilitates this staged approach to CKD in dogs (Table 1) and cats (Table 2). This classification scheme is based on the use of serum creatinine concentration to estimate degree of decline of GFR caused by the kidney disease. The IRIS proposal recognizes that the degree of azotemia in cats is not synonymous with that in dogs. This classification system employs 4 stages as Stage 1: Nonazotemic CKD disease, Stage 2: Mild renal azotemia, Stage 3: Moderate renal azotemia, and Stage 4: Severe renal azotemia.

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IRIS Classification of Chronic Kidney Disease

*IRIS: International Renal Interest Society

Stage Plasma creatinine µmol/l mg/dl Dogs Cats <140 <125 <1.6 <1.4 Comments

-

1

<125 <1.4

<140 <1.6

2

125 - 179 1.4 - 2.0

140 - 249 1.6 - 2.8

At risk of CKD For patients identified as `at risk' consider regular screening and taking steps to reduce risk factors Non-azotemic Some other renal abnormality present e.g. inadequate concentrating ability without identifiable non-renal cause; abnormal renal palpation and/or abnormal renal imaging findings; persistent proteinuria of renal origin; abnormal renal biopsy results, progressively elevating creatinine levels Mild renal azotemia [lower end of the range lies within the reference range for many labs but the insensitivity of creatinine as a screening test means that animals with creatinine values close to the upper limit of normality often have excretory failure] Clinical signs usually mild or absent Moderate renal azotaemia Systemic clinical signs may be present

3

180 - 439 2.1 - 5.0

250 - 439 2.9 ­ 5.0

4

>440 >5.0

>440 >5.0

Severe renal azotaemia Systemic clinical signs are usually present

DIAGNOSIS OF CKD

Once the GFR falls enough to cause the BUN and plasma creatinine concentration to increase, the diagnosis is generally straightforward. Usually at this time, the urine specific gravity will be <1.035 and plasma inorganic phosphorus levels are increased. Classically, CKD was diagnosed as the presence of renal azotemia accompanied by low urine specific gravity (<1.035). Unfortunately, these diagnostic criteria are incredibly insensitive, identifying the presence of CKD only after ¾ of functional renal mass has been destroyed. In early CKD when azotemia and clinical signs are absent, the diagnosis is sometimes made inadvertently, occurring as a result of imaging studies, laparotomy, or urinalyses conducted for other purposes. Osteoporosis may be seen radiographically, but this is a late finding in CKD that is generally not useful for identifying the presence of an otherwise masked case of CKD. Where measured by one of the specific tests mentioned above, the presence of a reduced GFR is a generally highly reliable test, though it must be remembered that reductions of GFR can be caused by renal, prerenal, and postrenal factors. A potentially useful early indicator of the presence of CKD is a urine specific gravity (USG) <1.035 despite dehydration. However, animals with early CKD, dogs with primary glomerular disease, and some cats with CKD of any severity, may retain the ability to concentrate urine to a specific gravity > 1.035. While measuring USG is a simple and readily available test, interpretation of a finding of a low USG can be complicated as the polyuria caused by a CKD must be differentiated from diseases which cause primary polydipsia (e.g., psychogenic polydipsia and hyperthyroidism) or those interfering directly with the urinary concentrating mechanism. These interfering conditions include diseases that lead to retention of solute in tubular fluid (e.g., diuretic administration and diabetes mellitus), central diabetes insipidus, and nephrogenic diabetes insipidus (e.g., hyperadrenocorticism, hypercalcemia, pyometra, and diseases causing septicemia). Adrenal insufficiency leads to a renal concentrating defect and may thus be confused with CKD because prerenal azotemia may be caused by the vomiting, diarrhea, and polydipsia associated with the former. Hyperkalemia, hyponatremia, and/or reduced

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plasma Na/K ratio is most helpful in establishing a tentative diagnosis of adrenal insufficiency, which must be confirmed by hormonal assay(s). Recently, tests for identification of proteinuria in veterinary patients that are both sensitive and specific have been developed.7 These include the protein-creatinine ratio and species-specific albuminuria tests. The ability to identify persistent renal proteinuria with these tests offers promise as being clinically useful for identifying early CKD (see subsequent section on Proteinuria in this chapter). The availability of reliable tests for proteinuria in dogs and cats make this a very attractive approach.

REFERENCES

1. Moe L, Heiene R. Estimation of glomerular filtration rate in dogs with 99M-Tc-DTPA and iohexol. Res Vet Sci 1995;58:138143. 2. Brown SA, Finco DR, Boudinot D, et al. Evaluation of a single injection method, using iohexol, for estimating glomerular filtration rate in cats and dogs. AJVR 1996;57:105-110. 3. Finco D, Braselton W, Cooper T. Relationship between plasma iohexol clearance and urianry exogenous creatinine clearance in dogs. J Vet Int Med 2001;15:368-373. 4. Gleadhill A, Michell AR. Evaluation of iohexol as a marker for the clinical measurement of glomerular filtration rate in dogs. Researchin Veterinary Science 1996;60:117-121. 5. Polzin DJ, Osborne CA. Update- conservative medical management of chronic renal failure In: Kirk RW, ed. Current Veterinary Therapy IX. Philadelphia: W.B. Suanders, 1986;1167-1173. 6. Krawiec D, Gelberg H. Chronic renal disease in cats In: RW K, ed. Current Veterinary Therapy X. Philadelphia: WB Saunders, 1989;1170-1173. 7. Lees GE, Brown SA, Elliott J, et al. Assessment and management of proteinuria in dogs and cats: 2004 ACVIM Forum Consensus Statement (small animal). J Vet Intern Med 2005;19:377-385.

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110TH PENN ANNUAL CONFERENCE - 2010

Wednesday, March 3, 2010 Thursday, March 4, 2010 Philadelphia, Pennsylvania

COMPANION ANIMAL: Renal

KRACKING KOMPLEX KIDNEY KASES

Scott A. Brown, VMD, PhD, DACVIM

Department Head, Small Animal Medicine and Surgery University of Georgia, College of Veterinary Medicine Winterville, GA

EVALUATION OF ANIMALS WITH CKD

For all animals with CKD, a thorough history and physical examination should be accompanied by complete clinical pathology testing which includes a biochemical panel, hematology, and urinalysis with specific proteinuria tests and aerobic bacterial culture. Survey radiography ± abdominal ultrasonography and blood pressure measurements should be performed. This initial battery of tests allows the veterinarian to evaluate the severity of the disease, establish a prognosis, follow the response to subsequent therapy, and identify complicating factors. As part of this evaluation, renal azotemia should be distinguished from other causes of azotemia and CKD should be distinguished from the more readily reversible acute kidney disease. Frequently, this latter differentiation may be accomplished with a careful history, physical examination, and evaluation of laboratory findings although occasionally a renal biopsy may be required. IRIS* Classification of Chronic Kidney Disease (CKD) Stage I Non-azotemic CKD Dogs: (mg/dl) Cats: (mg/dl) <1.4 1.4 ­ 2.0 2.1 to 5.0 >5.0 <1.4 1.4 ­ 2.0 2.1 to 5.0 >5.0 II Mild renal azotemic III Moderate renal azotemia IV Severe renal azotemia

*IRIS: International Renal Interest Society

NUTRITIONAL THERAPY

Nutrition plays a central role in the management of CKD.1 The response of each animal with CKD to the disease and to nutritional intervention will vary dramatically and individualized therapy is required; the only constant nutritional characteristic of renal insufficiency is inappetance and loss of body weight. Successful interventional nutrition must take all of these principles into account. For animals with CKD, the ideal goals of nutritional management are to maximize the quality and longevity of life by ensuring adequate intake of energy, limiting the extent of the clinical manifestations of the disease, and slowing the rate of progression of renal disease. Throughout all IRIS stages, nonspecific supportive treatment is best managed medically at home. In addition to providing a continual supply of fresh drinking water and encouraging (and documenting) adequate dietary intake, routine use of body condition scoring should be employed to assess adequacy of intake. Animals in the late stage I should generally be fed standard, commercially available maintenance diets, unless they are proteinuric (see section on Proteinuria below). In stages II-III, nutritional modifications serve as renoprotective therapy, assuming central importance here. As noted above, the kidney is susceptible to self-perpetuating injury, an inherent property of this organ, and the extent of this injury may be modified by adjustments in dietary intake of phosphorus (reduced) and n-3PUA (supplemented).2,3 The table below details target ranges for serum [PO4], based upon a review of available data. Significantly, the target is the low end of the normal range for serum [P], starting in IRIS Stage II. This will generally require the use of intestinal [PO4] binders in IRIS Stages III-IV. Nutritional modifications are symptomatic therapy in late stage III and stage IV, where clinical signs of uremia may be apparent. Most of the clinically observable abnormalities produced by the disruption of renal function are influenced by dietary intake of calories, phosphorus, sodium, potassium, protein, or acid load.

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IRIS Stage II

Target Serum P (mg/dL) 2.5 ­ 4.5

Target Serum P (mmol/L) 0.81 ­ 1.45

III

2.5 ­ 5.0

0.81 ­ 1.61

IV

2.5 ­ 6.0

0.81 ­ 1.94

PROTEINURIA

Recent findings have suggested that renal protein leak is not only a marker of severity of renal disease but also potentially a cause of renal injury.3-5 We now recognize that proteinuria is associated with increased risk of developing end-stage CKD in dogs and cats and that there may be an increased risk of mortality even in nonazotemic animals. Further, studies have shown that therapies that reduce the magnitude of proteinuria are often renoprotective. Proper management of proteinuria mandates following a three step paradigm. First, a finding of proteinuria should lead the clinician to Monitor the patient with confirmation by a specific test for proteinuria, such as a urine protein/creatinine ratio or assessment of albuminuria. When monitoring a proteinuric patient, it is important to determine if the proteinuria is transient or persistent (at least 2 tests at 2 weeks intervals). If persistent proteinuria is present in a patient with CKD, it is appropriate to advance to the second step of the paradigm (Investigate) and determine the site of origin of the protein (pre-renal, renal or post-renal) and determine if renal proteinuria is a sign of a complication (e.g., systemic hypertension) or evidence of a specific renal disease (e.g., glomerular nephritis) through careful patient evaluation. Proteinuria likely confers a poorer prognosis when the urine protein-to-creatinine ratio exceeds 0.5 in dogs or 0.4 in cats. If proteinuria of this magnitude is persistent and renal in origin in an animal with CKD, the clinician should consider proceeding to the third step of the paradigm (Intervene) by employing antiproteinuric therapy (e.g., ACEI, low protein diet, and/or n-3 PUFA supplementation). In this case, the antiproteinuric therapy is renoprotective, and is thus of higher priority in stages II, III, and early stage IV. Serial determinations of the level of proteinuria with a specific test for albuminuria or a urine proteinto-creatinine ratio should be used to evaluate the success of this approach. UPC value Dogs Cats IRIS Substage

<0.2

<0.2

Non-proteinuric (NP)

0.2 to 0.5

0.2 to 0.4

Borderline proteinuric (BP)

>0.5 *IRIS: International Renal Interest Society

>0.4

Proteinuric (P)

SUMMARY

The proper management of a dog or cat with CKD requires a clear understanding of the diagnostic and therapeutic priorities in the stage of disease at the time the patient is being managed. Early in the disease process (IRIS stage I), a careful

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evaluation of the kidney to identify the primary disease process and specific therapy to eliminate this disease is critical. In the middle stages (II and III), inherent progression and renoprotective therapy are paramount. In the final stage of CKD, IRIS stage IV, more frequent and thorough evaluations of the patient with institution of appropriate symptomatic therapy becomes the primary consideration of the veterinarian.

REFERENCES

1. Brown SA, Finco DR, Bartges JW, et al. Interventional nutrition for renal disease. Clin Tech Small Anim Pract 1998; 13:217-223. 2. Brown SA, Brown CA, Crowell WA, et al. Beneficial effects of chronic administration of dietary omega-3 polyunsaturated fatty acids in dogs with renal insufficiency. J Lab Clin Med 1998;131:447-455. 3. Brown SA, Brown CA, Crowell WA, et al. Effects of dietary polyunsaturated fatty acid supplementation in early renal insufficiency in dogs. J Lab Clin Med 2000;135:275-286. 4. Jacob F, Polzin DJ, Osborne CA, et al. Evaluation of the association between initial proteinuria and morbidity rate or death in dogs with naturally occurring chronic renal failure. J Am Vet Med Assoc 2005;226:393-400. 5. Lees GE, Brown SA, Elliott J, et al. Assessment and management of proteinuria in dogs and cats: 2004 ACVIM Forum Consensus Statement (small animal). J Vet Intern Med 2005;19:377-385. 6. Syme HM, Elliott J. Urinary protein excretion in cats with renal failure and/or hypertension. J Vet Int Med 2003;17:405A. 7. Syme HM, Elliott J. Relation of survival time and urinary protein excretion in cats with renal failure and/or hypertension. J Vet Int Med 2003;17:405A.

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110TH PENN ANNUAL CONFERENCE - 2010

Wednesday, March 3, 2010 Thursday, March 4, 2010 Philadelphia, Pennsylvania

COMPANION ANIMAL: Renal

DIAGNOSIS AND TREATMENT OF SYSTEMIC HYPERTENSION

Scott A. Brown, VMD, PhD, DACVIM

Department Head, Small Animal Medicine and Surgery University of Georgia, College of Veterinary Medicine Winterville, GA

MEASUREMENT OF BP

Diagnosis and management of hypertension in clinical patient must be based upon measurement of the patient's BP. To obtain reliable values in the measurement of BP, it is important to follow a standard protocol. The individual making the measurements should be patient and skilled in handling of animals, clients, and equipment. While it is critical for the veterinarian to fully appreciate the subtleties of BP measurement, it is generally preferred to have these measurements obtained by a skilled animal health technician that has been suitably trained in obtaining BP. Acquiring expertise in the use of indirect BP measurement devices requires hours of training; experienced operators enhance the reliability of indirect measurement.

1-4 The BP may be affected by stress or anxiety associated with the measurement process and these changes may result in a 5 false diagnosis of hypertension. This anxiety-induced, artifactual elevation of BP is often referred to as white-coat hypertension, a reference to the white coat of the medical professional measuring BP. Thus, it is important for the measurement room to be quiet and for 5-10 minutes to be provided for the patient to acclimate to the room. This reduces the mean anxiety-induced artifact (so-called white-coat-effect) to < 20 mmHg in cats.4 Similar results might be expected in dogs. While many causes of measurement error will lead to an erroneously high value for BP, this is not always the case. The minute-to-minute variability of BP, inconsistency of BP measuring devices, technical errors, transient dehydration, and/or parasympathetic overactivity all could lead to a falsely low value for BP.

The position of the patient and cuff should be one that is well tolerated with the cuff at, or close to, the level of the right atrium. The first measurement should be discarded and the average of 3 to 7 consecutive, consistent indirect measurements should be obtained. A standard form for recording results of the BP measurement should be developed. To allow for reliable comparison of serial measurements, each facility should follow a standard protocol carefully. This means that the animal position and attitude, cuff size and site, and cuff site circumference (cm) should be carefully considered (ideally these would also be noted in the animal record). All values obtained, rationale for excluding values, the final (mean) result, and interpretation of the result by the veterinarian should be noted.

TARGET OFGAN DAMAGE (TOD):

Systemic hypertension is problematic only because chronically sustained elevations of BP produce injury to tissues; the rationale for treatment of hypertension is the prevention of this injury. Damage that results from the presence of sustained high BP is commonly referred to as end-organ or target-organ damage (TOD) and the presence of TOD is generally a strong indication favoring antihypertensive therapy. In the kidney, TOD is generally manifest as an enhanced rate of decline of renal function, early renal death, and/or proteinuria. Further, microalbuminuria is a marker of hypertensive TOD in the heart and kidney in people16,17 and severity of albuminuria were directly related to degree of elevation of BP in an experimental study of chronic kidney disease in cats.18 Proteinuria was directly related to degree of elevation of BP and to rate of decline of GFR in an experimental study in dogs.19 Reduction of magnitude of proteinuria is perhaps the reliable evidence of benefit in an animal treated with antihypertensive agents, particularly in cats. With coexistent renal azotemia, TOD to the kidney is more likely to occur at systolic BP > 160 mmHg in dogs and cats,19-22 although there may actually be a linear relation between hypertensive injury and BP in dogs with CKD.19 Hypertension may be present in any stage of CKD, as serum creatinine is not directly related to BP. 23,24 Hypertensive cats and dogs often have very mild azotemia. Ocular lesions are observed in many cats with hypertension and while prevalence rates for ocular injury vary, it has been reported to be as high as 100%;11,14,15,25-31 ocular lesions are also a common lesion in hypertensive dogs.10,11,21,32 The syndrome33 is commonly termed hypertensive retinopathy and/or choroidopathy and has been frequently reported in dogs10,11,21] and cats 14,15,27,28,34-37. Exudative retinal detachment is the most commonly observed finding. Other lesions

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include retinal hemorrhage, multifocal retinal edema, retinal vessel tortuosity, retinal perivascular edema, papilledema, vitreal hemorrhage, hyphema, secondary glaucoma, and retinal degeneration (late sequel). Acute onset of blindness from complete, bilateral exudative retinal detachment may be a presenting complaint in both species.11,34,35 Effective antihypertensive treatment can lead to retinal reattachment, but restoration of vision30 generally occurs in only a minority14 of patients. Hypertensive ocular injury has been reported at systolic BP as low as 168 mmHg29 and there is a substantially elevated risk of occurrence when systolic BP exceeds 180 mmHg. 11,25,34,36 Hypertensive encephalopathy38 has been reported in dogs21 and cats,14,35,39 occurring as a well described entity in people characterized by white matter edema and vascular lesions.40,41 Neurological signs were reported in 29%14 and 46% of hypertensive cats.35 Hypertensive encephalopathy also occurs after renal transplantation in people42 and is a cause of otherwise unexplained death in this setting in cats.39,43,44 This syndrome, in its early phases, is responsive to antihypertensive therapy.18,39 Hypertensive encephalopathy is more likely to occur in cats with a sudden rise of BP and/or a systolic BP that exceeds 180 mmHg.18 Observed clinical signs are typical of intracranial disease and include lethargy, seizures, acute onset of altered mentation, altered behavior, disorientation, balance disturbances such as vestibular signs, head tilt, nystagmus, and focal neurological defects due to stroke-associated ischemia. Other CNS abnormalities, including hemorrhage and infarction, which occur with chronic hypertension in people45 are also observed in dogs and cats. Cardiac changes present in hypertensive dogs may include systolic murmurs and cardiac gallops10,46 and left ventricular hypertrophy 46,47. Cardiac abnormalities are frequent, occurring in about 4 of 5 hypertensive cats14,15,25 It is important to recognize that, when affected, the heart is a target organ and increased stroke volume is rarely the primary cause of hypertension in animals.14 Signs observed in affected cats include systolic murmur and gallop rhythm 14,15,48, cardiomegaly (generally left ventricular hypertrophy or LVH but echocardiographic findings are variable).14,34,35,47,49,50 Although LVH may not be a risk factor for reduced survival time,25 effective antihypertensive therapy may reduce the prevalence of LVH in affected cats.51 Cardiac failure and other serious complications are infrequent but may occur.14,35,52 Cats with previously undiagnosed hypertension may unexpectedly develop signs of congestive heart failure after receiving fluid therapy. Further, cats with secondary hypertension due to other causes (e.g., CKD) may die of cardiovascular complications15 as is frequently the case in hypertensive people.53 Epistaxis, presumably due to hypertension-induced vascular abnormalities, has been associated with systemic hypertension.

SELECTION OF PATIENTS TO SCREEN FOR THE PRESENCE OF HYPERTENSION:

There are at least two clear indications for evaluating BP in a patient. First, BP should be measured in patients with clinical abnormalities consistent with hypertensive TOD. A second indication for measurement of BP is the presence of diseases or conditions (see above) casually associated with secondary hypertension as well as those being treated with pharmacological agents that may elevate BP (see above). A thorough physical examination, including fuduscopic evaluation, cardiac auscultation, and neurologic examination should concurrently be performed in these at-risk populations to assess for TOD. While the positive relation between advancing age and prevalence of systemic hypertension is not as clear in animals as it is in people, conditions causing secondary hypertension are often more frequently observed in geriatric pets and it is prudent to routinely screen animals for the presence of these conditions (e.g., chronic kidney disease and hyperthyroidism).

DIAGNOSIS OF HYPERTENSION:

A decision to use antihypertensive therapy should always be based on reliable measurements of BP. Diagnosis should rarely be established on the basis of a single measurement session. Multiple measurements as well as thorough search for TOD and conditions that may cause secondary hypertension should be considered before establishing a diagnosis. In patients with TOD consistent with hypertension that may rapidly progress (i.e., hypertensive retinopathy/choroidopathy or encephalopathy), a single measurement of BP can be used to transiently establish a rationale for antihypertensive therapy. While there are interbreed differences in BP in dogs, only the mean difference (10 -20 mmHg higher values for each category) for Sight Hounds mandates separate categorization at this time. 54,55 It is anticipated that publication of data in specific breeds of dogs and cats may justify further modification of this recommendation in the future. Generally, BP is categorized on the basis of risk of developing subsequent TOD. In people, any reduction of BP that does not produce overt hypotension lowers the risk of TOD. Admittedly, this latter finding remains to be confirmed in dogs and cats.

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Table: Classification of blood pressure levels (mmHg) in dogs and cats based on risk for future target-organ damage (TOD) ­ Adapted from Guidelines of the International Renal Interest Society (IRIS) and the ACVIM Hypertension Consensus Statement (JVIM, 2007)

Systolic BP mm Hg <150 Diastolic BP mm Hg <95 Arterial Pressure Substage (AP) AP0 Minimal Risk AP1 Low Risk AP2 Moderate Risk AP3 High Risk No complications (nc) Complications (c) Risk not determined (RND) T

150 ­ 159

95 - 99

160 ­ 179

100 - 119

180

120

No evidence of end organ damage/complications: Evidence of end organ damage/complications: Blood pressure not measured: Treated:

MANAGEMENT OF THE HYPERTENSIVE PATIENT

The goals of this assessment include recognizing conditions that may be contributing to the elevation of BP, identifying and characterizing TOD, and determining if there are any seemingly unrelated concurrent conditions that may complicate antihypertensive therapy. Underlying diseases that may be causing secondary hypertension should be identified and treated while continuing to monitor BP. With the exception of advanced hypertensive choroidopathy or encephalopathy, antihypertensive therapy is generally not an emergency. Because hypertension is often a silent, slowly progressive condition requiring vigilance and life-long therapy, it is important to be absolutely certain about the diagnosis: a high BP measurement may represent idiopathic, secondary or white-coat hypertension. A decision to treat is made on the basis of categorization of risk for further TOD, characterization of concurrent conditions, and existing TOD. As hypertension in dogs and cats is most often secondary (80% based on current data), antihypertensive drug therapy by itself is often not sufficient. Initial considerations should always include (i) identification and management of conditions likely to be causing secondary hypertension and (ii) identification and treatment of TOD. Where possible, these considerations should be addressed with specific, targeted diagnostic and therapeutic regimens. Effective management of a condition causing secondary hypertension will lead to complete or partial resolution of the high BP in some, but not all, 7,21,23 Decisions to use antihypertensive drugs should be based on the integration of all clinically available information cases. and a decision to treat, which may effectively mandate lifelong drug therapy, warrants periodic, judicious re-evaluation. The therapy must be individualized to the patient and its concurrent conditions. Once daily treatment is ideal; fewer treatments are always preferred. A gradual, persistent reduction of BP is the therapeutic goal. Acute, severe decreases in BP should generally be avoided. If an antihypertensive agent of choice is only partially effective, the usual approach is to consider increasing the dosage or adding an additional drug. While not ideal, management of highly resistant hypertension in people often requires 4-5 agents, and most veterinary patients with significant hypertension will require more than one agent. It is often helpful to discuss the variable nature of response to antihypertensive medications with the owner when the first medication is prescribed. Although frequently recommended as an initial step in the pharmacological management of high BP, dietary salt restriction is controversial27,61,62 and available evidence suggests significant sodium restriction alone generally does not reduce BP 61-63 and in fact, activates the renin-angiotensin-aldosterone axis.10,62 and may actually elevate BP in certain settings.61,63 This latter effect may lead to progression of undesirable vascular, renal, and cardiac changes64-68 and necessitate the utilization of antihypertensive agents that interfere with this hormonal system (e.g., angiotensin-converting enzyme inhibitors, angiotensin receptor blockers (ARBs), and/or aldosterone receptor blockers). This is controversial, however, as high salt

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intake may produce adverse consequences in some settings,69 particularly in animals with chronic kidney disease.27 At this time there is no clear rationale and high dietary sodium chloride intake should be avoided in hypertensive patients but there is not a specific effort to be made solely to restrict dietary sodium chloride intake. Until more data are available, the selection of appropriate diet should be based on other patient-specific factors, such as underlying or concurrent diseases and palatability. Once a decision is made to treat an animal with high BP, therapeutic intervention will generally be with a pharmacological agent. Further, certain disease conditions may be best addressed with specific classes of agents, such as beta-blockers for hypertension associated hyperthyroidism or alpha- and beta-blockers or surgical excision for pheochromocytomas, aldosterone receptor blockers or surgical excision of adrenal tumors in animals with hypertension associated with hyperaldosteronism, or some combination of ACEI/ARB/Aldosterone receptor blockers for hypertension associated with renal disease in dogs,18,59,60,70,71. Angiotensin-converting enzyme inhibitors (ACEI) and calcium channel blockers (CCB) are the most widely used antihypertensive agents in veterinary medicine. In dogs, ACEI are generally recommended as the initial agent of choice. Although there has been some concern about acute exacerbation of azotemia with these agents, this is an unusual complication of ACEI therapy.72-75 Because ACEI preferentially dilate the efferent arteriole, they lower intraglomerular pressure60,72 and frequently reduce the magnitude of proteinuria.59,60,73 Reduction of the magnitude of proteinuria is an important therapeutic goal, as reduced proteinuria is associated with prolonged survival. Further, adverse cardiac and renal consequences of angiotensin II and aldosterone 64-68 may be attenuated by this class of agents. However, a secondary consequence of efferent arteriolar dilation is a theoretical tendency for glomerular filtration rate (GFR) to decline. Single nephron studies indicate that this is not necessarily the case in dogs60 or cats.72 In dogs and cats with chronic kidney disease not complicated by cardiovascular disease, the administration of ACEI commonly produces only very modest increases in serum creatinine concentration (<0.5 mg/dL; < 50 mol/L) and this degree of change is generally tolerable. ACEI have been shown to have no adverse effect on renal function, based on serum creatinine, when administered chronically to aged dogs with heart disease but not heart failure.76 ACEI should not, however, be used in dehydrated patients in which GFR may drop precipitously. These patients should be carefully rehydrated, and then re-evaluated before instituting antihypertensive therapy. In any case, a BP <120/60 mmHg combined with clinical findings of weakness, syncope, and/or tachycardia indicate systemic hypotension and therapy should be adjusted accordingly (Figure 2). In cats, although the renin-angiotensin-aldosterone axis may play a role in the genesis or maintenance of systemic hypertension,77-82 CCB are often preferred as first choice for antihypertensive therapy due to established efficacy 15,18,51,83,84 A mean decline in systolic BP of 40-55 mmHg is typically observed in cats with moderate to high risk of TOD15,83,84. Despite dramatic antihypertensive efficacy, CCB have not been shown to increase survival time in treated cats15 and their use may activate the systemic, or intrarenal, renin-angiotensin-system. A key predictive parameter is the effect on proteinuria: a renoprotective effect is predicted if the antihypertensive regimen used is antiproteinuric. In this setting, co-administration of ACEI and CCB is a consideration.70,85,86 Combination therapy may be especially useful in cats where there is some evidence for a beneficial effect of ACEI in chronic kidney disease73 and an established antihypertensive efficacy for CCB. This approach is being evaluated87 but is in need of further study. The goal of antihypertensive therapy is to reduce the magnitude, severity, and/or likelihood of TOD. It is important to recognize that hypertension is generally not an emergency and rapid reductions of BP should usually not be sought aggressively. Studies in people indicate that reduction of risk for TOD by antihypertensive therapy is a continuum and that the lower the BP, the lower the risk for TOD. Results of a recent laboratory study in dogs,19 suggest that BP is a continuous risk marker for progression of kidney disease and may in part justify a similar approach in veterinary patients. Regardless of the initial level of BP, the goal of therapy should be to maximally reduce the risk of TOD (SBP<150 and DBP < 95 mmHg) and that antihypertensive therapy should be adjusted on re-evaluation if BP > 150/95mmHg or systolic BP < 120 mmHg. Certainly, a minimal goal of therapy is to achieve a reduction in category of risk for TOD. Follow-up evaluations should include measurement of BP, serum creatinine concentration, urinalysis, funduscopic examination, and other specific assessments depending on the individual circumstances (e.g., TOD, causes of secondary hypertension, and concurrent conditions) of the patient. Since signs of progression TOD can be subtle, BP should be closely monitored over time in patients receiving antihypertensive therapy, even when hypertension is seemingly well-controlled. The frequency and nature of re-evaluations will vary depending on the BP category, stability of BP, other aspects of the health of the patient, and frequency of dosage adjustment to antihypertensive therapy. Assessment of any associated conditions or intercurrent diseases at intervals are dictated by standard management practices for those conditions. Animals with serious or rapidly progressive lesions (e.g., ocular or neurological signs) constitute a special category, regardless of level of BP, and should be re-evaluated in 1-3 days. In other cases, re-evaluation at 7-10 days following changes in therapy and at 1-4 month intervals

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depending on stability (more frequent if BP or other conditions are unstable) and level of elevation (more frequent if BP remains > 180 mmHg). Hospitalized patients, particularly those receiving fluid therapy or pharmacological agents with cardiovascular effects, should be assessed daily. For animals with TOD, there are organ specific markers that should be monitored in affected patients. For example, proteinuria and microalbuminuria are an adverse consequence of systemic hypertension in animals with co-existent chronic kidney disease. In evaluating the benefits of lowering BP in animals with chronic kidney disease, lessening the magnitude of proteinuria is perhaps the most effective treatment goal,88 particularly in cats.

REFERENCE LIST AVAILABLE UPON REQUEST

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COMPANION ANIMAL: Gastrointestinal Issues

G.I. MOTILITY DISORDERS: PATHOGENESIS, DIAGNOSIS, AND THERAPY

Robert J. Washabau, VMD, PhD, DACVIM

Professor of Medicine and Department Chair, Department of Veterinary Clinical Sciences College of Veterinary Medicine, University of Minnesota St. Paul, MN

CANINE IDIOPATHIC MEGAESOPHAGUS

Etiology - Idiopathic megaesophagus is the most common cause of regurgitation in the dog. The disorder is characterized by esophageal hypomotility and dilation, progressive regurgitation, and loss of body condition. Several forms of the syndrome have been described, including congenital idiopathic, acquired secondary, and acquired idiopathic megaesophagus. Congenital idiopathic megaesophagus is a generalized hypomotility and dilation of the esophagus causing regurgitation and failure to thrive in puppies shortly after weaning. An increased breed incidence has been reported in the Irish setter, Great Dane, German shepherd, Labrador retriever, Chinese Shar-Pei, and Newfoundland breeds, and autosomal dominant inheritance has been demonstrated in the Miniature Schnauzer and Fox terrier breeds. The pathogenesis of the congenital form is incompletely understood, although several studies have pointed to a defect in the vagal afferent innervation of the esophagus. Congenital idiopathic megaesophagus has been reported in several cats, and in one group of cats secondary to pyloric dysfunction. Acquired secondary megaesophagus may develop in association with a number of other conditions. Myasthenia gravis accounts for 25-30% of the secondary cases. In some cases of myasthenia gravis, regurgitation and weight loss may be the only presenting signs of the disease, whereas in most other cases of acquired secondary megaesophagus regurgitation is but one of many clinical signs including peripheral muscle weakness. Acquired secondary megaesophagus has also been associated with hypoadrenocorticism, lead poisoning, lupus myositis, and severe forms of esophagitis. Hypothyroidism has been suggested as a secondary cause of idiopathic megaesophagus but retrospective risk factor analysis has not identified it as an important cause. Most cases of adult-onset megaesophagus have no known etiology and are referred to as acquired idiopathic megaesophagus. The syndrome occurs spontaneously in adult dogs between 7 to 15 years of age without sex or breed predilection. The disorder has been compared erroneously to esophageal achalasia in humans. Achalasia is a failure of relaxation of the lower esophageal sphincter and ineffective peristalsis of the esophageal body. A similar disorder has never been rigorously documented in the dog. Several important differences between idiopathic megaesophagus in the dog and achalasia in humans have been documented. Although the etiology(ies) has not been identified, some studies have suggested a defect in the afferent neural response to esophageal distension similar to what has been reported in congenital megaesophagus. Clinical Examination Routine hematology, serum biochemistry, and urinalysis should be performed in all cases to investigate possible secondary causes of megaesophagus (e.g. hypoadrenocorticism). Survey radiographs will be diagnostic for most cases of megaesophagus. Contrast radiographs may be necessary in some cases to confirm the diagnosis, evaluate motility, and exclude foreign bodies or obstruction as the cause of the megaesophagus. Endoscopy will confirm the diagnosis and may further reveal esophagitis, a frequent finding in canine idiopathic megaesophagus. If acquired secondary megaesophagus is suspected, additional diagnostic tests should be considered, for example: serology for nicotinic acetylcholine receptor antibody, ACTH stimulation, serology for antinuclear antibody, serum creatine phosphokinase activity, electromyography and nerve conduction velocity, and muscle and nerve biopsy. Additional medical investigation will be dependent upon the individual case presentation. Hypothyroidism has been cited as an important cause of idiopathic megaesophagus in the dog, although risk factor analysis has not revealed a clear association. Thyroid function testing (e.g., TSH assay, TSH stimulation, free and total thyroid hormones) should be performed in individual suspicious cases. Treatment Animals with secondary acquired megaesophagus should be appropriately differentiated from other esophageal disorders and treated. Dogs affected with myasthenia gravis should be treated with pyridostigmine (1.0-3.0 mg/kg PO BID) and/or

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corticosteroids (prednisone 1.0-2.0 mg/kg PO or SQ BID), dogs affected with hypothyroidism should be treated with levothyroxine (22 g/kg PO BID), and dogs affected with polymyositis should be treated with prednisone (1.0-2.0 mg/kg PO BID). If secondary disease can be excluded, therapy for the congenital or acquired idiopathic megaesophagus patient should be directed at nutritional management and treatment of aspiration pneumonia. Affected animals should be fed a high-calorie diet, in small frequent feedings, from an elevated or upright position to take advantage of gravity drainage through a non-peristaltic esophagus. Dietary consistency should be formulated to produce the fewest clinical signs. Some animals handle liquid diets quite well, while others do better with solid meals. Animals that cannot maintain adequate nutritional balance with oral intake should be fed by temporary or permanent tube gastrostomy. Gastrostomy tubes can be placed surgically or percutaneously with endoscopic guidance. Smooth muscle prokinetic (e.g., metoclopramide or cisapride) therapy has been advocated for stimulating esophageal peristalsis in affected animals, however metoclopramide and cisapride will not likely have much of an effect on the striated muscle of the canine esophageal body. Bethanechol has been shown to stimulate esophageal propagating contractions in some affected dogs and is therefore a more appropriate prokinetic agent for the therapy of this disorder. Because of the high incidence of esophagitis in canine idiopathic megaesophagus, affected animals should also be medicated with oral sucralfate suspensions (1 g q8h for large dogs 0.5 g q 8h for smaller dogs 0.25 to 0.5 g q8h to q12h for cats). Prognosis Animals with congenital idiopathic megaesophagus have a fair prognosis. With adequate attention to caloric needs and episodes of aspiration pneumonia, many animals will develop improved esophageal motility over several months. Pet owners must be committed to months of physical therapy and nutritional support. The morbidity and mortality of acquired idiopathic megaesophagus remain unacceptably high.

GASTRIC EMPTYING DISORDERS

Gastric emptying disorders are fairly common in dogs and cats. They result from disease processes that alter normal gastric functions, i.e. storage of ingesta, mixing and dispersion of food particles, and timely emptying of gastric contents into the small intestine. Disorders of gastric emptying arise from mechanical obstruction, or from defective propulsion. Anatomic lesions (e.g. malignancy, hyperplasia, foreign bodies) cause delayed gastric emptying because of mechanical obstruction. Diagnosis and management of mechanical obstruction is usually straight-forward. Disorders of defective propulsion, on the other hand, cause delayed gastric emptying because of abnormalities in myenteric neuronal or gastric smooth muscle function, or because of abnormalities in antropyloroduodenal coordination. A number of primary conditions have been associated with these functional disorders, including infectious or inflammatory disease, ulcer, and post-surgical gastroparesis. Delayed gastric emptying has also been associated with a number of secondary conditions, including electrolyte disturbances, metabolic disorders, concurrent drug usage (cholinergic antagonists, adrenergic agonists, opioid agonists), acute stress, and acute abdominal inflammation. Recovery from gastric dilation/volvulus is almost always associated with significant myoelectrical and motor abnormalities in the dog. Diagnosis and management of the delayed gastric emptying disorders may not be so straight-forward. Nutritional and medical management, including smooth muscle prokinetic agents (e.g., cisapride, erythromycin, and ranitidine), are important components of therapy.

SMALL INTESTINAL TRANSIT DISORDERS

A number of small intestinal transit disorders have been described in dogs and cats, including enteritis, post-surgical pseudo-obstruction, nematode infection, intestinal sclerosis, and radiation enteritis. Vomiting and diarrhea are the most important clinical signs associated with these disorders. Overgrowth of small intestinal bacteria, a common sequela to disordered motility, contributes to these clinical signs. Transit disorders associated with mechanical obstruction should always be differentiated and treated appropriately. Delayed transit associated with functional disorders should be managed with dietary modification (low fat diets) and prokinetic agents (cisapride, tegaserod, or metoclopramide). Tegaserod has been reported to normalize intestinal transit in opioid-induced bowel dysfunction in dogs.

COLONIC MOTILITY DISORDERS

History Constipation, obstipation, and megacolon may be observed in cats of any age, sex, or breed, however, most cases are observed in middle aged (mean = 5.8 years), male cats (70% male, 30% female) of Domestic Shorthair (46%), Domestic Longhair (15%), or Siamese (12%) breeding. Affected cats are usually presented for reduced, absent, or painful defecation for a period of time ranging from days to weeks or months. Some cats are observed making multiple, unproductive attempts to

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defecate in the litter box, while other cats may sit in the litter box for prolonged periods of time without assuming a defecation posture. Dry, hardened feces are observed inside and outside of the litter box. Occasionally, chronically constipated cats have intermittent episodes of hematochezia or diarrhea due to the mucosal irritant effect of dehydrated feces. Physical Examination Colonic impaction is a consistent physical examination finding in affected cats. Other findings will depend upon the severity and pathogenesis of constipation. Dehydration, weight loss, debilitation, abdominal pain, and mild to moderate mesenteric lymphadenopathy may be observed in cats with severe idiopathic megacolon. Colonic impaction may be so severe in such cases as to render it difficult to differentiate impaction from colonic, mesenteric, or other abdominal neoplasia. Cats with constipation due to dysautonomia may have other signs of autonomic nervous system failure, such as urinary and fecal incontinence, regurgitation due to megaesophagus, mydriasis, decreased lacrimation, prolapse of the nictitating membrane, and bradycardia. Digital rectal examination should be carefully performed with sedation or anesthesia especially in those cats with recurring bouts of constipation. Pelvic fracture malunion may be detected on rectal examination in cats with pelvic trauma. Rectal examination might also identify other unusual causes of constipation, such as foreign bodies, rectal diverticula, stricture, inflammation, or neoplasia. Chronic tenesmus may be associated with perineal herniation in some cases. A complete neurologic examination with special emphasis on caudal spinal cord function should be performed to identify neurologic causes of constipation, e.g. spinal cord injury, pelvic nerve trauma, and Manx sacral spinal cord deformity. Differential Diagnoses Several authors have emphasized the importance of considering an extensive list of differential diagnoses (e.g. neuromuscular, mechanical, inflammatory, metabolic/endocrine, pharmacologic, environmental, and behavioral causes) for the obstipated cat. A review of published cases, however, suggests that 96% of cases of obstipation are accounted for by idiopathic megacolon (62%), pelvic canal stenosis (23%), nerve injury (6%), or Manx sacral spinal cord deformity (5%). A smaller number of cases are accounted for by complications of colopexy (1%) and colonic neoplasia (1%); colonic hypo- or aganglionosis was suspected, but not proved, in another 2% of cases. Inflammatory, pharmacologic, and environmental/behavioral causes were not cited as predisposing factors in any of the original case reports. Endocrine factors (obesity, n=5; hypothyroidism, n=1) were cited in several cases, but were not necessarily impugned as part of the pathogenesis of megacolon. Pathogenesis The pathogenesis of idiopathic megacolon has been historically attributed to a primary neurogenic or degenerative neuromuscular disorder. While it seems clear that a small number of cases (11%) result from neurologic disease, the vast majority (>90%) of cases have no evidence of neurologic disease. Some of the idiopathic cases may instead involve disturbances of colonic smooth muscle as suggested by several studies. In vitro isometric stress measurments were performed on colonic smooth muscle segments obtained from cats suffering from idiopathic dilated megacolon. These studies suggested that the disorder of feline idiopathic megacolon is a generalized dysfunction of colonic smooth muscle, and that treatments aimed at stimulating colonic smooth muscle contraction might improve colonic motility. Therapeutic Plan The specific therapeutic plan will depend upon the severity of constipation and the underlying cause. Medical therapy may not be necessary with first episodes of constipation. First episodes are often transient and resolve without therapy. Affected animals should always be re-hydrated if dehydration has contributed to the onset of clinical signs. Mild to moderate or recurrent episodes of constipation usually require some medical intervention. These cases may be managed, often on an outpatient basis, with dietary modification, water enemas, oral or suppository laxatives, and/or colonic prokinetic agents. Severe cases of constipation usually require brief periods of hospitalization to correct metabolic abnormalities and to evacuate impacted feces using water enemas, manual extraction of retained feces, or both. Followup therapy in such cases is directed at correcting predisposing factors and preventing recurrence. Subtotal colectomy will become necessary in cats suffering from obstipation or idiopathic dilated megacolon. These cats, by definition, are unresponsive to medical therapy. Pelvic osteotomy without colectomy may be sufficient for some cats suffering from pelvic canal stenosis and hypertrophic megacolon.

GASTROINTESTINAL PROKINETIC THERAPY

Dopaminergic Antagonistic Drugs

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The dopaminergic antagonists are a group of drugs with gastrointestinal prokinetic and antiemetic effects at peripheral (prokinetic) or central (antiemetic) dopamine D2 receptors. The best representatives in this classification, metoclopramide and domperidone, reverse gastric relaxation induced by dopamine infusion in dogs, and they abolish vomiting associated with apomorphine therapy. Although the role of dopamine receptors in chemoreceptor trigger zone-induced vomiting is fairly well established, there is no definitive evidence that inhibitory dopaminergic neurons regulate gastrointestinal motility. The prokinetic effects of metoclopramide and domperidone thus may not be readily or exclusively explained by dopamine receptor antagonism. Some dopaminergic antagonists (e.g., metoclopramide) have other pharmacologic properties, e.g., 5-HT3 receptor antagonism and 5-HT4 receptor agonism. Domperidone also has 2- and 2-adrenergic receptor antagonistic effects. The characterization of these drugs as dopaminergic antagonists is convenient but may not properly describe their overall in vivo effects. Metoclopramide increases the amplitude and frequency of antral contractions; inhibits fundic receptive relaxation; and coordinates gastric, pyloric, and duodenal motility, all of which result in accelerated gastric emptying. Metoclopramide appears to have continuing clinical application as a gastric prokinetic agent in the dog and cat, although the serotonergic agonists appear to be more potent. Domperidone appears to be less efficacious as a gastric prokinetic agent. Although effective in humans, domperidone actually decreases the frequency of corporeal, pyloric, and duodenal contractions and deteriorates antropyloroduodenal coordination in the dog by decreasing the frequency of contractions spreading from the antrum or pylorus to the duodenum. Serotonergic Drugs Drugs acting on gastrointestinal 5-hydroxytryptamine (5-HT or serotonin) receptors have potent motility effects. As prokinetic agents, the serotonergic drugs bind 5-HT4 receptors on enteric cholinergic neurons inducing depolarization and contraction of gastrointestinal smooth muscle. These drugs are not entirely selective for the 5-HT4 receptor, however. Some of the putative 5-HT4 receptor agonists also have 5-HT1 and 5-HT3 antagonistic effects on enteric cholinergic neurons, and direct non-cholinergic (perhaps 5-HT2a) effects on colonic smooth muscle. Cisapride is perhaps the best example in this classification although it has been withdrawn from several markets, including the United States, Canada, and several western European countries. Cisapride accelerates gastric emptying in dogs by stimulating pyloric and duodenal motor activity, by enhancing antropyloroduodenal coordination, and by increasing the mean propagation distance of duodenal contractions. In this regard, cisapride appears to be superior to metoclopramide and domperidone in stimulating gastric emptying. Dosages of cisapride in the range of 0.05-0.2 mg/kg enhance gastric emptying in dogs with normal gastric emptying. Dosages in the range of 0.5-1.0 mg/kg are needed to enhance gastric emptying in dogs with delayed gastric emptying induced by 2adrenergic agonists, dopamine, disopyramide, or antral tachygastria. Cisapride was widely used in the management of canine and feline gastric emptying, intestinal transit, and colonic motility disorders throughout most of the 1990's. Cisapride was withdrawn from the American, Canadian and certain Western European in July of 2000 following reports of untoward cardiac side effects in human patients. Cisapride causes QT interval prolongation and slowing of cardiac repolarization via blockade of the rapid component of the delayed rectifier potassium channel (IKr). This effect may result in a fatal ventricular arrhythmia referred to as torsades de pointes. Similar effects have been characterized in canine cardiac Purkinje fibers, but in vivo effects have not yet been reported in dogs or cats. The withdrawal of cisapride has created a clear need for new G.I. prokinetic agents although cisapride continues to be available from compounding pharmacies throughout the United States. Tegaserod (SDZ HTF919 - Novartis Corporation) is a potent partial non-benzamide agonist at 5-HT4 receptors and a weak agonist at 5-HT1D receptors. Tegaserod has definite prokinetic effects in the canine colon. Intravenous doses of tegaserod (0.03-0.3 mg/kg) accelerate colonic transit in dogs during the first hour after intravenous administration (0.03 mg/kg). The highest doses of tegaserod (0.1 and 0.3 mg/mg) have no greater efficacy than lower doses (0.03 mg/kg), suggesting the possibility that tegaserod may stimulate canine colonic motility through a receptor-independent mechanism, or that tegaserod may act at sites other than 5-HT4 receptors at higher doses. The motor mechanisms responsible for tegaserod-induced canine colonic propulsion are unclear. High amplitude propagated phasic contractions are thought to be responsible for mass movements, but they were not observed during tegaserod infusion. Contraction, amplitude, and motility indices were not different postprandially among treatment groups, so the mechanism of the tegaserod effect will require more detailed investigation in the dog.

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In vitro studies suggest that tegaserod does not prolong the QT interval or delay cardiac repolarization as has been occasionally reported with cisapride. Clinical efficacy has been demonstrated in human motility disorders, and new drug approval was rewarded by the U.S. Food and Drug Administration in September 2002. Tegaserod was removed from the American market in 2007 following reports of QT interval prolongation. Prucalopride (RO93877 - Janssen Pharmaceutical) is a potent partial benzamide agonist at 5-HT4 receptors, but is without effect on other 5-HT receptors or cholinesterase enzyme activity. Tegaserod has potent prokinetic effects on canine and feline colonic motility. Prucalopride dose-dependently (0.02-1.25 mg/kg) stimulates giant migrating contractions (GMC's) and defecation in the dog. The prucalopride effect is observed most prominently in the first hour after administration, suggesting that the prucalopride effect is a direct effect on the colon rather than on total gut transit time. Oral and intravenous doses appear to be equipotent again implying a high oral bioavailability. Prucalopride also enhances defecation frequency in healthy cats. Cats treated with prucalopride at a dose of 0.64 mg/kg experience increased defecation within the first hour of administration. Fecal consistency is not altered by prucalopride at this dosage. Prucalopride also appears to stimulate gastric emptying in the dog. In lidamidine-induced delayed gastric emptying in dogs, prucalopride (0.01-0.16 mg/kg) dose-dependently accelerates gastric emptying of dextrose solutions. The prucalopride effect is equipotent following oral and intravenous administration suggesting that prucalopride may have a high oral bioavailability. Prucalopride has not yet been marketed in the United States or elsewhere. Motilin-Like Drugs The antibiotic properties of erythromycin and other macrolides were discovered in the early 1950's. Since that time, erythromycin has been widely used in treating patients with gram-positive and gram-negative bacterial and mycoplasmal infections. Physicians and veterinarians noted that erythromycin therapy was accompanied by frequent gastrointestinal side effects including nausea and vomiting. This occurrence suggested to researchers that erythromycin might have effects on gastrointestinal motility. It was subsequently demonstrated that microbially-effective doses of erythromycin stimulate retrograde peristalsis and vomiting in dogs, and that lower microbially-ineffective doses of erythromycin stimulate migrating motility complexes and antegrade peristalsis similar to that induced by the endogenous gastrointestinal hormone, motilin. Erythromycin accelerates gastric emptying by inducing antral contractions similar to phase III of the interdigestive state. The strong contractions associated with phase III normally occur only during the fasted state when they clear the stomach of large indigestible solids. After meals, intravenous or oral erythromycin accelerates gastric emptying of solid meals in dogs. EM574 is 250 times more potent than erythromycin in inducing phase III contractions in dogs and it has no antibacterial activity. EM574 is as effective as cisapride in normalizing gastric contractility and emptying in dogs with clonidineinduced gastroparesis in dogs. Acetylcholinesterase Inhibitors and Cholinomimetic Agents Ranitidine and nizatidine, classic histamine H2 receptor antagonists, stimulate gastrointestinal motility by inhibiting acetylcholinesterase activity. As parasympathetic potentiating agents, ranitidine and nizatidine stimulate gastric emptying and small intestinal and colonic motility. The prokinetic effects of ranitidine and nizatidine appear to be more prominent in the proximal gastrointestinal tract (i.e., gastric emptying). Other members of this classification, e.g., cimetidine and famotidine, apparently have no effect on gastrointestinal motility. Bethanechol is a cholinomimetic agent that binds muscarinic cholinergic receptors and stimulates motility throughout the gastrointestinal tract. Ranitidine and nizatidine stimulate gastric antral contractions at gastric anti-secretory dosages (ranitidine 1.0-2.0 mg/kg PO BID; nizatidine 2.5-5.0 mg/kg PO BID) and may be useful as gastric prokinetic agents in dogs and cats.

NEW DEVELOPMENTS IN PROKINETIC THERAPY

Prostaglandin E1 analogues Misoprostol is a prostaglandin E1 analogue that reduces the incidence of nonsteroidal anti-inflammatory drug-induced gastric injury. The main side effects of misoprostol therapy are abdominal discomfort, cramping, and diarrhea. Dog studies suggest that prostaglandins may initiate a giant migrating complex pattern and increase colonic propulsive activity. In vitro studies of misoprostol show that it stimulates feline and canine colonic smooth muscle contraction. Given its limited toxicity, misoprostol may be useful in dogs and cats with severe refractory constipation.

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5-HT Serotonergic Agonists The 5-HT4 receptor appears to hold the most interest and promise for future drug development. 5-HT4 receptor activation can cause relaxation or contraction depending on the region, cell type, and animal species. In the dog, the effects of selective 5-HT4 receptor agonists suggest that these receptors are present on jejunal mucosa, ileal mucosa, gastric cholinergic neurons, and circular colonic smooth muscle cells. Increased motor activity following 5-HT4 receptor activation results from increased release of acetylcholine from cholinergic neurons, and relaxation results from 5-HT4 receptors on smooth muscle cells. Development of 5-HT4 ligands is somewhat constrained by the effects these drugs have on cardiac 5HT4 receptors and the delayed rectifier potassium channel (IKr). Some, but not all, 5-HT4 agonists prolong the QT interval and delay cardiac repolarization. Molecular biology experiments have revealed differences in the carboxyl terminus of smooth muscle and cardiac muscle 5-HT4 receptors, but these amino acids differences are distant from the receptor binding site. Thus, receptor sub-types may exist but they may not be important from a functional or therapeutic standpoint. CJ-033,466 - Pfizer Pharmaceutical A new 5-HT4 agonist has been identified that has high 5-HT4 molar potency with only limited effects on other 5-HT or non-5HT receptors. CJ-033,466 has a higher binding affinity for canine 5-HT4 receptors than cisapride, mosapride, and tegaserod, stimulates canine fasting and fed gastric motility at doses from 0.03-0.3 mg/kg, and restores canine gastric motility in a canine experimental delayed gastric emptying disorders. This new gastroprokinetic agent is quickly moving toward approval and marketing in Japan, and may quickly following in the United States.

SUGGESTED READINGS

1. Washabau RJ. Gastrointestinal Motility Disorders and G.I. Prokinetic Therapy. In, Veterinary Clinics of North America, Willard MD, ed. Philadelphia: WB Saunders Co., 2003, 1007-1028. 2. Washabau RJ, Holt D. Pathogenesis, Diagnosis, and Therapy of Feline Idiopathic Megacolon. In, Veterinary Clinics of North America, 1999; vol. 29: 589-603. 3. Hall JE, Washabau RJ. Diagnosis and Treatment of Gastric Motility Disorders. In, Veterinary Clinics of North America, 1999; vol. 29: 377-395. rd 4. Washabau RJ, Holt DE (2003). Pathophysiology of Gastrointestinal Disease. In, Textbook of Veterinary Surgery. 3 edition. Ed. D Slatter, WB Saunders Company, Philadelphia, pp 530-555. 5. Orihata M, Sarna SK. Contractile mechanisms of action of gastroprokinetic agents: cisapride, metoclopramide, and domperidone. Amer J Physiol 1994; 266: G665-G676. 6. Mikami T, Ochi Y, Suzuki K, et al. CH-033,466, a novel and selective 5-HT receptor partial agonist: pharmacologic profile in vitro and gastroprokinetic effect in conscious dogs. J Pharmacol Exp Therap 2008; 325: 190-199. 7. Hall JA, Washabau RJ. Gastrointestinal prokinetic therapy: dopaminergic antagonist drugs. Compend Contin Educ Pract Vet 19(2): 214-221, 1997. 8. Washabau RJ, Hall JA. Gastrointestinal prokinetic therapy: serotonergic drugs. Compend Contin Educ Pract Vet 1997; 19(4): 473-480. 9. Hall JA, Washabau RJ. Gastrointestinal prokinetic therapy: motilin-like drugs. Comp Contin Educ Pract Vet 1997; 19(3): 281-288. 10. Hall JA, Washabau RJ. Gastrointestinal prokinetic therapy: acetylcholinesterase inhibitors. Compend. Contin. Educ. Pract. Vet. 1997; 19(5): 615-621.

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FORMULARY - GASTROINTESTINAL PROKINETIC AGENTS

Mechanism/Example Dopaminergic D2 Antagonists Metoclopramide GES, stomach, intestine CRTZ Vomiting disorders G.E. reflux, delayed gastric emptying, ileus Vomiting disorders, G.E. reflux 0.2-0.5 mg/kg PO, IV TID; 0.01-0.02 mg/kg/hr infusion Sites of activity Indications Dose

Domperidone

GES, CRTZ

0.05-0.10 mg/kg PO BID

Serotonergic (5-HT4) Agonists Cisapride GES, stomach, intestine colon, CRTZ G.E. reflux, delayed 0.1-0.5 mg/kg PO TID gastric emptying, ileus constipation, vomiting Constipation, ileus 0.05-0.10 mg/kg PO, IV BID Delayed gastric emptying, Not yet approved constipation

Tegaserod Prucalopride

Intestine, colon Stomach, colon

Motilin-like Drugs Erythromycin GES, stomach, intestine G.E. reflux, delayed 0.5-1.0 mg/kg PO, IV TID emptying, constipation (dogs)

Acetylcholinesterase Inhibitors Ranitidine Stomach, colon Delayed gastric emptying, 1.0-2.0 mg/kg PO BID-TID constipation Delayed gastric emptying constipation 2.5-5.0 mg/kg PO BID-TID

Nizatidine

Stomach, colon

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COMPANION ANIMAL: Gastrointestinal Issues

DIFFICULT VOMITING DISORDERS: PATHOGENESIS, DIAGNOSIS, THERAPY

Robert J. Washabau, VMD, PhD, DACVIM

Professor of Medicine and Department Chair, Department of Veterinary Clinical Sciences College of Veterinary Medicine, University of Minnesota St. Paul, MN

HISTORY TAKING

A complete and detailed history is the first step in establishing a correct diagnosis of a vomiting disorder. The patient's signalment will usually establish some level of probability for many of the differential diagnoses. For example, adrenocortical insufficiency would be an important differential diagnosis for a two year old dog presented with an acute history of vomiting and muscular weakness, with or without diarrhea. Similarly, the acute onset of vomiting in an unvaccinated puppy should alert the veterinarian to the possibility of an infectious disease, for example, parvoviral or distemper viral gastroenteritis. Chronic vomiting in an eleven year old dog, on the other hand, would elicit a different set of differential diagnoses. Following consideration of the patient's signalment, the history taking should ascertain vaccination status, travel history, and any recent dietary changes. Previous medical problems, medication history, and the possible ingestion of toxic substances or foreign bodies should also be ascertained. These pieces of information can be quite useful in formulating a list of differential diagnoses. Next, the veterinarian should be convinced that the pet owner is describing vomiting, and not some other sign. For example, the coughing associated with inflammatory disorders of the upper airway will often be described as vomiting by many pet owners. Gagging is also occasionally confused with vomiting. A careful history taking will usually discriminate coughing and gagging from vomiting. Pet owners will also often confuse regurgitation and dysphagia with vomiting. Regurgitation is the passive evacuation of ingested food from the pharynx and/or esophagus; the premonitory signs of retching and abdominal contractions seen with vomiting are not observed with regurgitation. The description of regurgitation by a pet owner would suggest a more proximal disorder of the pharynx or esophagus. Dysphagia or difficulty in swallowing would also suggest a more proximal disorder of the pharynx. The history taking should then elicit the duration, frequency, and time of vomiting episodes, as well as the relationship of vomiting to food and water consumption. Disorders of vomiting that are of short duration are usually self-limiting and not worthy of extensive investigation; chronic vomiting histories, on the other hand, are more serious and certainly require a more detailed investigation. Frequent vomiting usually occurs as result of systemic, metabolic, or endocrine disorders or severe inflammatory disorders of the primary gastrointestinal tract. Vomiting that occurs in the immediate post-prandial period is usually suggestive of overeating, excitement, or disorders of the esophageal body or esophageal hiatus (e.g. hiatal hernia). Conversely, vomiting of undigested or partially digested food 8 or more hours post-prandially would suggest a distal gastric (corpus, antrum, and pylorus) motility disorder or obstruction. Vomiting of water would be more suggestive of a proximal gastric (cardia, fundus) motility disorder. Vomiting during the early morning hours often may result from gastroesophageal reflux. Finally, the physical characteristics of the vomitus, including the color, amount, odor, consistency, and the presence or absence of blood or bile should be ascertained. Undigested food in the vomitus implies a gastric etiology, while digested food (chyme) implies an intestinal etiology for the vomiting. The presence of blood in the vomitus implies disruption of the gastrointestinal mucosa; blood may appear as frank red clots or as a dark brown "coffee-grounds" material resulting from acid proteolysis. Bile in the vomitus usually suggests only that the pylorus has permitted bile reflux. However, bile salts are known to increase the permeability of the gastric mucosal barrier resulting in a syndrome of bile reflux gastritis. Bilious vomiting, therefore, might provide a clue to the pathogenesis of the disorder. A fecal odor has been described with lower intestinal (jejuno-ileal) obstruction.

PHYSICAL EXAMINATION

Examination of the mouth and pharyngeal structures often provide important clues to the pathogenesis of vomiting, e.g. uremic breath or ulcers, icteric mucous membranes, severe pharyngitis or pharyngeal string foreign bodies. The physical examination finding of generalized lymphadenopathy would suggest neoplasia or a systemic inflammatory disease as the

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pathogenesis of the vomiting. Hence, all lymph nodes should be carefully palpated to determine if they are enlarged and/or painful. The presence of fever on physical examination would likewise suggest an inflammatory pathogenesis for the vomiting disorder. Extreme bradycardia or other rhythm disturbance detected upon cardiac auscultation might be an important sign of a metabolic disturbance such as adrenocortical insufficiency or septic shock. The abdomen should then be carefully palpated for effusion (e.g. peritonitis), masses (e.g. carcinomatosis or other malignancy), pain (e.g. peritonitis, pancreatitis, or nephritis), gaseous or fluid distension of the intestine (e.g. obstruction), kidney size and shape (e.g. endstage fibrotic kidneys or nephritis), liver size (e.g. hepatitis), uterine distension (e.g. pyometra), and urinary bladder size (e.g. bladder obstruction). Rectal examination might also provide some evidence of pain or hematochezia (e.g. colitis), worms (e.g. hook or whipworms), or painful prostatomegaly (e.g. prostatitis or prostatic neoplasia). Finally, examination of the central nervous system should be considered, especially in the animal in which the cause of vomiting is not so obvious. Some animals with intervertebral disc disease will vomit because of pain.

DIFFERENTIAL DIAGNOSIS

After identifying problems from the history and physical examination, a reasonable list of differential diagnoses may then be considered based upon pathogenetic mechanism: abdominal alimentary, abdominal extra-alimentary, systemicmetabolic-endocrine, drug-induced, toxicity, diet-related, and neurologic disorders.

DIAGNOSTIC WORKUP

If a definitive diagnosis is not established from the history and physical examination, then the following "initial tests" are warranted: complete blood count, serum chemistry, urinalysis, fecal parasitologic examination, and abdominal radiographs. Peripheral eosinophilia in a complete blood count would suggest the possibilities of systemic mast cell disease, intestinal parasitism, or adrenocortical insufficiency. Leukopenia and neutropenia might be observed in the acute phase of a viral gastroenteritis. Leukocytosis, on the other hand, might suggest an inflammatory disorder like acute pancreatitis. The serum chemistry will often help identify systemic, metabolic, and endocrine causes of vomiting. For example: 1) azotemia and hyperphosphatemia suggest that the vomiting has resulted from chronic renal failure; 2) hyperglycemia, acidosis, glucosuria, and ketonuria suggest diabetic ketoacidosis as the cause of vomiting; 3) hyponatremia and hyperkalemia suggest adrenocortical insufficiency; 4) amylasemia and lipasemia suggest acute pancreatitis; 5) increases in serum liver enzyme activities (ALT, AST, ALP) suggest primary liver disease; and, 6) hypercalcemia suggests parathyroid or other malignancy. Urinalysis will be useful in differentiating pre-renal and primary renal azotemia, while fecal examination may provide evidence of intestinal helminth infestation. Survey radiographs of the abdomen are certainly indicated in the initial workup of a vomiting disorder. The abdominal radiographs will provide useful information about the abdominal alimentary and extra-alimentary structures. The decision to perform additional tests is based on response to empirical therapies and initial test results. Further tests might include: thoracic radiography, abdominal ultrasonography, contrast radiography, ACTH stimulation, liver function tests, gastrointestinal endoscopy, and laparotomy.

ANTI-EMETIC THERAPY

Physiology of Emesis: The essential components of the emetic reflex are visceral receptors, vagal and sympathetic afferent neurons, a chemoreceptor trigger zone (CRTZ) located within the area postrema that is sensitive to blood-borne substances, and an emetic center within the reticular formation of the medulla oblongata receiving input from vagal and sympathetic neurons, CRTZ, vestibular apparatus, and cerebral cortex. An important concept dating from the early 1950's is that vomiting occurs either through activation of the CRTZ by blood-borne substances (humoral pathway), or through activation of the emetic center by vago-sympathetic, CRTZ, vestibular, or cerebrocortical neurons (neural pathway). Thus, activation of the CRTZ by a variety of humoral emetogenic substances (e.g. uremic toxins, cardiac glycosides, and apomorphine) is abolished by surgical ablation of the area postrema, but not by vagotomy or sympathectomy. In contrast, neural activation of the emetic center by gastric disease (e.g. gastritis) is abolished by vagotomy or sympathectomy, but not by ablation of the area postrema. Many experimental data have been readily explained by this two-component model. Despite contemporary reexamination, there is still good agreement on the two general patterns of emesis, one humoral and one neural. Current therapy is largely based on these assumptions. Many of the spontaneous vomiting disorders of cats and dogs, particularly those of the primary gastrointestinal tract, are believed to result from activation of the neural pathway. Vomiting associated with primary gastrointestinal tract disease (e.g., inflammation, infection, malignancy, toxicity) results from activation of visceral receptors, afferent neurons, and the

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emetic center. Efferent information transmitted back to the gastrointestinal tract stimulates the motor correlates of vomiting (retrograde duodenal and gastric contractions, relaxation of the caudal esophageal sphincter, gastroesophageal reflux, opening of the proximal esophageal sphincter, and evacuation of gastrointestinal contents). A neural pathway can also be involved in vomiting associated with motion sickness. Motion within the semicircular canals is transduced to vestibulo-cochlear neurons that ultimately synapse in the CRTZ or emetic center. Cats and dogs experience motion sickness, although the neuroanatomy and pharmacology appear to be somewhat different between the two species. Histaminergic neurons and the CRTZ are involved in motion sickness in the dog, whereas neither are involved in motion sickness in the cat. A neural pathway involving cerebrocortical neurons may be involved in vomiting disorders associated with anxiety or anticipation, but these are probably more important in human beings. The essential component of the humoral pathway is the chemoreceptor trigger zone (CRTZ) located within the area postrema that is sensitive to blood-borne substances. Receptors within the CRTZ may be activated by many endogenous (e.g., uremic-, hepatoencephalopoathic-, or endo-toxins) and exogenous (e.g., digitalis glycosides, apomorphine) bloodborne substances. Most pharmacological approaches to anti-emetic therapy have been based on neurotransmitterreceptor interactions at the CRTZ, emphasizing the humoral pathway of emesis. The neural pathway has received much less emphasis even though it is a much more important pathway. Pharmacology of Emesis: Vomiting is initiated through activation of one or more neurons in the CRTZ or emetic center. Anti-Emetic Classifications

A number of anti-emetic drugs have been formulated based on the aforementioned neurotransmitter-receptor systems. These drugs may be classified as: 2 adrenergic antagonists, D2 dopaminergic antagonists, H1 and H2 histaminergic antagonists, M1 muscarinic cholinergic antagonists, ENK enkephalinergic mixed agonists/antagonists, and 5-HT3 serotonergic antagonists. The 5HT4 serotonergic agonists are not direct anti-emetic drugs per se, but may have an indirect anti-emetic effect by promoting gastrointestinal motility.

Physiology of Vomiting

Pharmacology of Vomiting

Anxiety, Anticipation

Apomorphine Uremic Toxins Hepatotoxins Endotoxins Cardiac Glycosides

Motion

Cerebral Cortex

ENK, 2

Chemoreceptor Trigger Zone

D2, H1, 2, 5-HT3, M1 NK1, ENK,

Dog

Oculo Vestibular System

H1, M1, NMDA

t Ca

Cerebral Cortex

Chemoreceptor Trigger Zone

Emetic Center

Dog

Oculo Vestibular System

t

Afferent Neuron

NTS

NK1

DMV

2, 5-HT1A

Ca

RFN

Efferent Neuron

Afferent Neuron

Gastrointestinal Tract

Efferent Neuron

Gastrointestinal Tract

5-HT3 NK1 5-HT4, M2, MOT

Rational Use of Anti-Emetic Agents in the Diagnosed Patient: 1. Motion Sickness - Motion sickness is believed to arise from stimulation of labyrinthine structures in the inner ear. The chemoreceptor trigger zone and H1 histaminergic receptors are involved in this pathway in the dog, but apparently they are less importantly involved in the cat. Motion sickness in the cat is probably best treated with an -adrenergic antagonist, e.g., chlorpromazine, instead of a pure H1 histaminergic antagonist. 2. Uremia ­ Vomiting associated with uremia has both central and peripheral components. The central component of uremic vomiting is associated with activation of CRTZ D2 dopaminergic receptors by circulating uremic toxins. The central component is best treated with a D2 dopaminergic antagonist, e.g. metoclopramide, or a 5-HT3 antagonist, particularly in the cat. The peripheral component of uremic vomiting is associated with uremic gastritis and is best treated with acid secretory inhibitors (e.g. ranitidine 1-2 mg/kg q 12 h IV; omeprazole 0.7 mg/kg q 12 h PO) to diminish gastric parietal cell H+

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ion secretion, and with chemical barrier diffusion barriers (e.g., sucralfate 0.25-0.5 grams q 8-12 h PO) to provide a barrier to H+ ion back diffusion. 3. Cancer Chemotherapy ­ Certain cancer chemotherapies (e.g. cisplatinum, cyclophosphamide) are associated with a high incidence of vomiting. Chemotherapy-induced emesis is mediated by 5-HT3 serotonergic receptors, either in the CRTZ or in vagal afferent neurons. Antagonists of the 5-HT3 serotonergic receptor (e.g. ondansetron, granisetron, tropisetron) abolish the vomiting associated with cisplatinum administration in the cat. Although metoclopramide has some 5-HT3 antagonistic properties, it has not proved very useful in chemotherapy-induced emesis. 4. Delayed Gastric Emptying Orders ­ Disorders of delayed gastric emptying (e.g. gastritis, metabolic derangements, postoperative gastric dilatation and volvulus) may cause an animal to experience nausea and vomiting. Treatment of these disorders with cholinomimetic agents has been associated with untoward side effects. Contemporary therapy consists of 5HT3 serotonergic agonists (e.g., cisapride, metoclopramide), cholinesterase inhibitors (e.g., ranitidine or nizatidine), and motilin agonists (e.g., low dose erythromycin ­ dog only). Cisapride is superior to metoclopramide in the treatment of gastric emptying disorders in cats and dogs. Ranitidine and nizatidine inhibit acetylcholinesterase activity in addition to their effects on histamine H2 receptors in the gastric mucosa. Both drugs (ranitidine and nizatidine) stimulate gastric emptying in the cat and dog. Erythromycin stimulates phase III migrating myoelectric complex (MMC) activity in the dog, but the migrating spike complex (MSC) activity of the cat is under different physiologic regulation. Newer Anti-Emetic Therapy - Neurokinin-1 Receptor Antagonists Examples Maropitant Maropitant Aprepitant Lanepitant Dapitant · · · Tradename Cerenia Cerenia Emend Pharma Pfizer Pfizer Merck Dosage 1.0 mg kg SQ SID x 5 2.0 mg kg PO SID x 5

de la Puente-Redondo VA, Tilt N, Rowan TG, et al. Efficacy of maropitant for treatment and prevention of emesis caused by cisplatin in dogs. Am. J. Vet. Res. 2007; 68: 48Vail DM, Rodabaugh HS, Conder GA, et al.. Efficacy of maropitant in prevention and treatment of cisplatinuminduced emesis. Vet. Comp. Oncology 2007; 5: 38de la Puente-Redondo VA, Siedek EM, Benchaoui HA, et al. Anti-emetic efficacy of maropitant in the treatment of ongoing emesis caused by a wide range of underlying clinical etiologies in canine patients in Europe. J. Small Anim. Practice 2007; 48: 93FDA Application ­ January 29, 2007 ­ NADA 141-262 & 141-263 - Maropitant 1.0 mg/kg SQ effective against emesis due to syrup of ipecac, apomorphine, and cisplatin.

·

Anti-Emetic Strategies for the Undiagnosed Patient (1) NK1 Neurokinin Antagonists (2) 5-HT3 Serotonergic Antagonists (3) 2-Adrenergic Antagonists (4) D2 Dopaminergic Antagonists Irrational Usage of Anti-Emetic Agents Systemic hypotension Phenothiazines Pre-existing epilepsy Phenothiazines G.I. obstruction Prokinetic agents G.I. infection All Classes G.I. toxicity All Classes Prolonged usage All Classes

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COMPANION ANIMAL: Gastrointestinal Issues

CANINE INFLAMMATORY BOWEL DISEASE: DIAGNOSIS AND THERAPY

Robert J. Washabau, VMD, PhD, DACVIM

Professor of Medicine and Department Chair, Department of Veterinary Clinical Sciences College of Veterinary Medicine, University of Minnesota St. Paul, MN

DEFINITION OF IBD

Inflammatory bowel disease (IBD) may be defined using clinical, pathogenetic, imaging, histologic, immunologic, pathophysiologic, and genetic criteria. Clinical Criteria IBD has been defined clinically as a spectrum of gastrointestinal disorders associated with chronic inflammation of the stomach, intestine and/or colon of unknown etiology. A clinical diagnosis of IBD is considered only if affected animals have: (1) persistent (>3 weeks in duration) gastrointestinal signs (anorexia, vomiting, weight loss, diarrhea, hematochezia, mucousy feces), (2) failure to respond to symptomatic therapies (parasiticides, antibiotics, gastrointestinal protectants) alone, (3) failure to document other causes of gastroenterocolitis by thorough diagnostic evaluation, and (4) histologic diagnosis of benign intestinal inflammation. Small bowel and large bowel forms of IBD have been reported in both dogs and cats, although large bowel IBD appears to be more prevalent in the dog. Pathogenetic Criteria Known causes of intestinal diarrhea should first be considered: food sensitivity reaction, bacterial infection, parasitic infection, fungal infection, pancreatic insufficiency, intestinal neoplasia, lymphangiectasia (canine), and hyperthyroidism (feline). Most current hypotheses on the pathogenesis of IBD hold that the gut has sustained reactivity to endogenous bacterial and/or food antigens. Histologic Criteria IBD has been defined histologically by the type of inflammatory infiltrate (neutrophilic, eosinophilic, lymphocytic, plasmacytic, granulomatous), associated mucosal pathology (villus atrophy, fusion, crypt collapse), distribution of the lesion (focal or generalized, superficial or deep), severity (mild, moderate, severe), mucosal thickness (mild, moderate, severe), and topography (gastric fundus, gastric antrum, duodenum, jejunum, ileum, cecum, ascending colon, descending colon). As with large intestinal IBD, subjective interpretation of small intestinal IBD lesions has made it difficult to compare tissue findings between pathologists. Subjectivity in histologic assessments has led to the development of several IBD grading systems. Immunologic Criteria IBD has been defined immunologically by the innate and adaptive response of the mucosa to gastrointestinal antigens. Although the precise immunologic events of canine and feline IBD remain to be determined, a prevailing hypothesis for the development of IBD is the loss of immunologic tolerance to the normal bacterial flora or food antigens, leading to abnormal T cell immune reactivity in the gut microenvironment. Genetically engineered animal models (e.g., IL-2, IL-10, and T cell receptor knockouts) that develop IBD involve alterations in T cell development and/or function suggesting that T cell populations are responsible for the homeostatic regulation of mucosal immune responses. Immunohistochemical studies of canine IBD have demonstrated an increase in the T cell population of the lamina propria, including CD3+ cells and CD4+ cells, as well as macrophages, neutrophils, and IgA-containing plasma cells. Many of the immunologic features of canine IBD can be explained as an indirect consequence of mucosal T cell activation. Enterocytes are also likely involved in the immunopathogenesis of IBD. Enterocytes are capable of behaving as antigen-presenting cells, and interleukins (e.g., IL-7 and IL-15) produced by enterocytes during acute inflammation activate mucosal lymphocytes. Up-regulation of Toll-like receptor 4 (TLR4) and Toll-like receptor 2 (TLR2) expression contribute to the innate immune response of the colon. Thus, + the pathogenesis and pathophysiology of IBD appears to involve the activation of a subset of CD4 T cells within the intestinal epithelium that overproduce inflammatory cytokines with concomitant loss of a subset of CD4+ T cells, and their

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associated cytokines, which normally regulate the inflammatory response and protect the gut from injury. Enterocytes, behaving as antigen-presenting cells, contribute to the pathogenesis of this disease. Pathophysiologic Criteria IBD may be defined pathophysiologically in terms of changes in transport, blood flow, and motility. The clinical signs of IBD, whether small or large bowel, have long been attributed to the pathophysiology of malabsorption and hypersecretion, but experimental models of canine IBD have instead related clinical signs to the emergence of abnormality motility patterns. The pathophysiology of small intestinal IBD is explained by at least two interdependent mechanisms: the mucosal immune response, and accompanying changes in motility. Immune Responses A generic inflammatory response involving cellular elements (B and T lymphocytes, plasma cells, macrophages, and dendritic cells), secretomotor neurons (e.g., VIP, substance P, and cholinergic neurons), cytokines and interleukins, and inflammatory mediators (e.g., leukotrienes, prostanoids, reactive oxygen metabolites, nitric oxide, 5-HT, IFN-, TNF-, and platelet-activating factor) is typical of canine and feline inflammatory bowel disease. There are many similarities between the inflammatory response of the small and large intestine, but recent immunologic studies suggest that IBD of the canine small intestine is a mixed Th1/Th2 response whereas IBD of the canine colon may be more of a Th1 type response with elaboration of IL-2, IL-12, INF-, and TNF-. Motility Changes Experimental studies of canine small (and large) intestinal IBD have shown that many of the clinical signs are related to motor abnormalities of the gastrointestinal tract. Ethanol and acetic acid perfusion of the canine ileum or colon induces a form of IBD syndrome indistinguishable from the natural condition. Inflammation in this model suppresses the normal phasic contractions of the colon, including the migrating motility complex, and triggers the emergence of giant migrating contractions (GMCs). The appearance of these GMCs in association with inflammation is a major factor in producing diarrhea, abdominal cramping, and urgency of defecation. GMCs are powerful lumen-occluding contractions that rapidly propel pancreatic, biliary, and intestinal secretions in the fasting state, and undigested food in the fed state, to the colon to increase its osmotic load. Malabsorption results from direct injury to the epithelial cells and from ultrarapid propulsion of intestinal contents by giant migrating contractions (GMCs) so that sufficient mucosal contact time is not allowed for digestion and absorption to take place. Inflammation impairs the regulation of the colonic motility patterns at several levels, i.e., enteric neurons, interstitial cells of Cajal, and circular smooth muscle cells. Inflammation-induced changes in the amplitude and duration of the smooth muscle slow wave plateau potentials contribute to the suppression of rhythmic phasic contractions (RPCs). These alterations likely have their origin in structural as well as functional damage to the interstitial cells of Cajal. At the same time that inflammation suppresses the (RPCs), inflammation sensitizes the colon to the stimulation of GMCs by the neurotransmitter substance P. These findings suggest that SP increases the frequency of GMCs during inflammation, and that selective inhibition of GMCs during inflammation may minimize the symptoms of diarrhea, abdominal discomfort, and urgency of defecation associated with these contractions. Inflammation suppresses the generation of tone and phasic contractions in the circular smooth muscle cells through multiple molecular mechanisms. Inflammation shifts muscarinic receptor expression in circular smooth muscles from the M3 to the M2 subtype. This shift has the effect of reducing the overall contractility of the smooth muscle cell. Inflammation also impairs calcium influx and down-regulates the expression of the L-type calcium channel, which may be important in suppressing phasic contractions and tone while concurrently stimulating GMCs in the inflamed colon. Changes in the openstate probability of the large conductance calcium-activated potassium channels (KCa) partially attenuate this effect. Inflammation also modifies the signal transduction pathways of circular smooth muscle cells. Phospholipase A2 and protein kinase C (PKC) expression and activation are significantly altered by colonic inflammation and this may partially account for the suppression of tone and phasic contractions. PKC , , and isoenzyme expression is down-regulated, PKC and isoenzyme expression is up-regulated, and the cytosol-to-membrane translocation of PKC is impaired. The L-type calcium channel, already reduced in its expression, is one of the molecular targets of PKC. Inflammation also activates the transcription factor NF-B which further suppresses cell contractility.

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Genetic Criteria IBD may be defined by genetic criteria in several animal species. Crohn's disease and ulcerative colitis are more common in certain human genotypes, and a mutation in the NOD2 gene (nucleotide-binding oligomerization domain2) has been found in a sub-group of patients with Crohn's disease. Genetic influences have not yet been identified in canine or feline IBD, but certain breeds (e.g., German shepherds, Boxers) appear to be at increased risk for the disease.

OVERVIEW OF PATHOPHYSIOLOGY OF IBD:

Inflammation impairs motility by inducing changes in receptor, signal transduction, and ion channel activity in smooth muscle cells and enteric neurons. Changes include but not are limited to a shift in muscarinic receptor expression from M3 to M2 receptor subtype, impaired calcium mobilization, down-regulation of L-type calcium channel expression, changes in the open-state probability of the large conductance calcium-activated potassium channels (KCa), down-regulation of phospholipase A2 and protein kinase C , , and isoenzymes, and activation of the transcription factor NF-B in smooth muscle cells. Inflammation also sensitizes the colon to the stimulation of GMCs by the neurotransmitter substance P. PKC = protein kinase C, PLA2 = Phospholipase A2 , M = muscarinic, NF-B = Nuclear factor-B, KCa = Calcium-activated potassium channel, SP = substance P, ACh = acetylcholine.

Pathogenetic

Imaging

Histologic

I.B.D.

Immunologic

Pathophysiologic

Genetic

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SP

Enteric Neuron

ACh Smooth Muscle Cell PKC PKC IKB NFKB

M2 M3

Cao

2+

Ko

+

PLA2 Ca2+

i

K

+ i

CLINICAL EXAMINATION

The clinical signs of large intestinal IBD are those of a large bowel-type diarrhea, i.e., marked increased frequency, reduced fecal volume per defecation, blood pigments and mucous in feces, and tenesmus. Anorexia, weight loss, and vomiting are occasionally reported in animals with severe IBD of the colon or concurrent IBD of the stomach and/or small intestine. Clinical signs usually wax and wane in their severity. A transient response to symptomatic therapy may occur during the initial stages of IBD. As the condition progresses, diarrhea gradually increases in its frequency and intensity, and may become continuous. In some cases the first bowel movement of the day may be normal or nearly normal, whereas successive bowel movements are reduced in volume and progressively more urgent and painful. During severe episodes, mild fever, depression, and anorexia may occur. There does not appear to be any sex predilection, but age may be a risk factor with IBD appearing more frequently in middle aged animals (mean age approximately 6 years with a range of 6 months to 20 years). German shepherd and Boxer dogs are at increased risk for IBD, and pure-breed cats appear to be at greater risk. Cats more often present with an upper gastrointestinal form of IBD, whereas dogs are at risk for both small and large bowel IBD. Physical examination is unremarkable in most cases. Thickened bowel loops may be detected during abdominal palpation if the small bowel is concurrently involved. Digital examination of the anorecturm may evoke pain or reveal irregular mucosa, and blood pigments and mucous may be evident on the exam glove.

DIAGNOSIS

Complete blood counts, serum chemistries, and urinalyses are often normal in mild cases of large bowel IBD. Chronic cases may have one or more subtle abnormalities. One review of canine and feline IBD reported several hematologic abnormalities including mild anemia, leukocytosis, neutrophilia with and without a left shift, eosinophilia, eosinopenia, lymphocytopenia, monocytosis, and basophilia. The same study reported several biochemical abnormalities including

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increased activities of serum alanine aminotransferase and alkaline phosphatase, hypoalbuminemia, hypoproteinemia, hyperamylasemia, hyperglobulinemia, hypokalemia, hypocholesterolemia, and hyperglycemia. No consistent abnormality in the complete blood count or serum chemistry has been identified. A scoring index for disease activity in canine IBD was recently developed that relates severity of clinical signs to serum acute-phase protein (C-reactive protein, serum amyloid A) concentrations. The canine IBD activity index (CIBDAI) assigns levels of severity to each of several gastroenterologic signs (e.g., anorexia, vomiting, weight loss, diarrhea), and it appears to be a reliable index of mucosal inflammation in canine IBD. Interestingly, both the activity index and serum concentrations of C-reactive protein (CRP) improve with successful treatment, suggesting that serum CRP is suitable for the laboratory evaluation of therapy in canine IBD. Other acute-phase proteins were less specific than CRP. One important caveat that should be emphasized is that altered CRP is not prima facie evidence of gastrointestinal inflammation. Concurrent infections or other inflammatory conditions could cause an acute-phase response, including CRP, in affected patients.

TREATMENT

Management of IBD consists of 1) dietary therapy, 2) exercise, 3) antibiotics, 4) probiotics, 5) anti-diarrheal agents, 6) restoration of normal motility, 7) anti-inflammatory or immunosuppressive therapy, and 8) behavioral modification. 1. DIETARY THERAPY The precise immunologic mechanisms of canine and feline IBD have not yet been determined, but a prevailing hypothesis for the development of IBD is the loss of immunologic tolerance to the normal bacterial flora or food antigens. Accordingly, dietary modification may prove useful in the management of canine and feline IBD. Several nutritional strategies have been proposed including novel proteins, hydrolyzed diets, anti-oxidant diets, medium chain triglyceride supplementation, low fat diets, modifications in the omega-6/omega-3 (-6/-3) fatty acid ratio, and fiber supplementation. Of these strategies, some evidence-based medicine has emerged for the use of novel protein, hydrolyzed, and fiber-supplemented diets. Food sensitivity reactions were suspected or documented in 49% of cats presented because of gastroenterologic problems (with or without concurrent dermatologic problems) in a prospective study of adverse food reactions in cats. Beef, wheat, and corn gluten were the primary ingredients responsible for food sensitivity reactions in that study, and most of the cats responded to the feeding of a chicken- or venison-based selected-protein diet for a minimum of 4 weeks. The authors concluded that adverse reactions to dietary staples are common in cats with chronic gastrointestinal problems and that they can be successfully managed by feeded selected-protein diets. Further support for this concept comes from studies in which gastroenterologic or dermatologic clinical signs were significantly improved by the feeding of novel proteins. Evidence is accruing that hydrolyzed diets may be useful in the nutritional management of canine IBD. The conceptual basis of the hydrolyzed diet is that oligopeptides are of insufficient size and structure to induce antigen recognition or presentation. In one preliminary study, dogs with inflammatory bowel disease showed significant improvement following the feeding of a hydrolyzed diet although they had failed to respond to the feeding of a novel protein. Clinical improvement could not be solely attributed to the hydrolyzed nature of the protein source because the test diet had other modified features, i.e., high digestibility, cornstarch rather than intact grains, medium chain triglycerides, and an altered ratio of -6 to -3 polyunsaturated fatty acids. Additional studies will be required to ascertain the efficacy of this nutritional strategy in the management of IBD. Fiber-supplemented diets may be useful in the management of irritable bowel syndrome (IBS) in the dog. IBS is a poorly defined syndrome in the dog that may or may not bear resemblance to IBS in humans. Canine IBS has been defined as a chronic large-bowel type diarrhea without known cause and without evidence of colonic inflammation on colonoscopy or biopsy. Dogs fulfilling these criteria were successfully managed with soluble fiber (psyllium hydrophilic mucilloid) supplementation of a highly digestible diet. 2. EXERCISE Experimental IBD in the dog is accompanied by significant abnormalities in the normal colonic motility patterns. Physical exercise has been shown to disrupt the colonic MMCs and to increase the total duration of contractions that are organized as non-migrating motor complexes during the fed state. Exercise also induces GMCs, defecation, and mass movement in both the fasted and fed states. The increased motor activity of the colon and extra GMCs that result from physical exercise may aid in normal colonic motor function.

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3. ANTIBIOTICS Some IBD cases are initiated by true enteric pathogens, while others are complicated by small intestinal bacterial overgrowth. Some IBD cases may show short term responsiveness to one or more antibiotics, e.g., tylosin, metronidazole, or oxytetracycline. 4. PROBIOTICS Probiotics are living organisms with low or no pathogenicity that exert beneficial effects (e.g., stimulation of innate and acquired immunity) on the health of the host. The Gram-positive commensal lactic acid bacteria (e.g., Lactobacilli) have many beneficial health effects, including enhanced lymphocyte proliferation, innate and acquired immunity, and antiinflammatory cytokine production. Lactobacillus rhamnosus GG, a bacterium used in the production of yogurt, is effective in preventing and treating diarrhea, recurrent Clostridia difficile infection, primary rotavirus infection, and atopic dermatitis in humans. Lactobacillus rhamnosus GG has been safely colonized in the canine gastrointestinal tract, although probiotic effects in the canine intestine have not been firmly established. The probiotic organism, Enterococcus faecium (SF68), has been safely colonized in the canine gastrointestinal tract, and it has been shown to increase fecal IgA content and circulating mature B (CD21+/MHC class II+) cells in young puppies. It has been suggested that this probiotic may be useful in the prevention or treatment of canine gastrointestinal disease. This organism may, however, enhance Campylobacter jejuni adhesion and colonization of the dog intestine, perhaps conferring carrier status on colonized dogs. Two recent studies have shown that many commercial veterinary probiotic preparations are not accurately represented by label claims. Quality control appears to be deficient for many of these formulations. Until these products are more tightly regulated, veterinarians should probably view product claims with some skepticism. 5. ANTI-DIARRHEAL AGENTS Prostaglandin Synthetase Inhibitors - Sulfasalazine - 10-25 mg/kg TID-QID, PO - 5-aminosalicylate - 5-10 mg/kg PO, TID-QID (dog) ,-Opioid Agonists ­ These drugs stimulate circular smooth muscle contraction and, therefore,intestinal segmentation. It has been shown more recently that these drugs also stimulate absorption, and inhibit secretion of, fluid and electrolytes. - Loperamide 0.08 mg/kg TID, PO-preferred drug - Diphenoxylate 0.05-0.10 mg/kg TID-QID, PO-available in Lomotil 5-HT3 Serotonin Antagonists - Antagonists of the neuronal 5-HT3 receptor inhibit Cl- and H2O secretion from intestinal epithelial cells. - Ondansetron (Zofran, Glaxo) - 0.5-1.0 mg/kg BID, PO - Granisetron (Kytril, SmithKline Beecham) - 0.5-1.0 mg/kg BID, PO 2-Adrenergic Antagonists - These drugs must be used carefully as they can activate 2-adrenergic receptors in the chemoreceptor trigger zone and cause vomiting. - Clonidine 5-10 g/kg BID-TID, SQ/PO 6. RESTORATION OF NORMAL MOTILITY The mixed ,-opioid agonist, loperamide, stimulates colonic fluid and electrolyte absorption while inhibiting colonic propulsive motility. Loperamide (0.08 mg/kg PO TID-QID) may be beneficial in the treatment of difficult or refractory cases of large bowel-type IBD. 7. ANTI-INFLAMMATORY/IMMUNOSUPPRESSIVE THERAPY Sulfasalazine ­ Sulfasalazine is a highly effective prostaglandin synthetase inhibitor that has proven efficacy in the therapy of large bowel IBD in the dog. Sulfasalazine is a compound molecule of 5-aminosalicylate (meselamine) and sulfapyridine linked in an azo chemical bond. Following oral dosing, most of the sulfasalazine is transported to the distal gastrointestinal tract where cecal and colonic bacteria metabolize the drug to its component parts. Sulfapyridine is largely absorbed by the colonic mucosa but much of the 5-aminosalicylate remains in the colonic lumen where it inhibits mucosal lipoxygenase and the inflammatory cascade. Sulfasalazine has been recommended for the treatment of canine large bowel IBD at doses of 10-25 mg/kg PO TID for 4-6 weeks. With resolution of clinical signs, sulfasalazine dosages are gradually decreased by 25 per

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cent at 2-week intervals and eventually discontinued while maintaining dietary management. Salicylates are readily absorbed and induce toxicity in cats, therefore this drug classification should be used with great caution in cats. If used in cats, some authors have recommended using half of the recommended dog dose (i.e., 5-12.5 mg/kg PO TID. Sulfasalazine usage has been associated with the development of keratoconjunctivitis sicca in the dog, so tear production should be assessed subjectively (by the pet owner) and objectively (by the veterinarian) during usage. Other 5-Aminosalicylates ­ This drug classification was developed to reduce the toxicity of the sulfapyridine portion of the parent molecule (sulfasalazine) and to enhance the efficacy of the 5-aminosalicylate portion. Meselamine (Dipentum, Asachol) and dimeselamine (Olsalazine) are available for use in the treatment of canine large bowel IBD. Olsalazine has been used at a dosage of 5-10 mg/kg PO TID in the dog. Despite the formulation of sulfa-free 5-aminosalicylate preparations, instances of keratoconjunctivitis sicca have still been reported in the dog. Metronidazole ­ Metronidazole (10-20 mg/kg PO BID-TID) has been used in the treatment of mild to moderate cases of large bowel IBD in both dogs and cats. Metronidazole has been used either as a single agent or in conjunction with 5aminosalicylates or glucocorticoids. Metronidazole is believed to have several beneficial properties, including antibacterial, anti-protozoal, and immunomodulatory effects. Side effects include anorexia, hypersalivation, and vomiting at recommended doses and neurotoxicity (ataxia, nystagmus, head title, and seizures) at higher doses. Side effects usually resolve with discontinuation of therapy but diazepam may accelerate recovery of individual patients. Glucocorticoids ­ Anti-inflammatory doses of prednisone or prednisolone (1-2 mg/kg PO SID) may be used to treat IBD in dogs that have failed to respond to dietary management, sulfasalazine, or metronidazole, and as adjunctive therapy to dietary modification in feline IBD. Prednisone or prednisolone is used most frequently, as both have short durations of action, are cost-effective, and are widely available. Equipotent doses of dexamethasone are equally effective but may have more deleterious effects on brush border enzyme activity. Prednisone should be used for 2-4 weeks depending upon the severity of the clinical signs. Higher doses of prednisone (e.g., 2-4 mg/kg PO SID) may be needed to control severe forms of eosinophilic colitis or hypereosinophilic syndrome in cats. Combination therapy with sulfasalazine, metronidazole, or azothioprine may reduce the overall dosage of prednisone needed to achieve remission of clinical signs. As with sulfasalazine, the dose of glucocorticoid may be reduced by 25% at 1-2 week intervals while hopefully maintaining remission with dietary modification. Because of steroid side effects and suppression of the hypothalamic-pituitary-adrenal axis, several alternative glucocorticoids have been developed that have excellent topical (i.e., mucosal) anti-inflammatory activity but are significantly metabolized during first pass hepatic metabolism. Budesonide has been used for many years as an inhaled medication for asthma, and an enteric-coated form of the drug is now available for treatment of IBD in humans (and animals). There is little evidence-based medicine in support of the use of this medication in canine or feline IBD, but doses of 1 mg/cat or 1 mg/dog per day have been used with some success in anecdotal cases. Azathioprine ­ Azathioprine is a purine analog that, following DNA incorporation, inhibits lymphocyte activation and proliferation. It is rarely effective as a single agent, and it should instead be used as adjunctive therapy with glucocorticoids. Azathioprine may have a significant steroid-sparing effect in IBD. Doses of 2 mg/kg PO q 24 hours in dogs and 0.3 mg/kg PO q 48 hours in cats have been used with some success in IBD. It may take several weeks or months of therapy for azathioprine to become maximally effective. Cats particularly should be monitored for side effects, including myelosuppression, hepatic disease, and acute pancreatic necrosis. Cyclosporine ­ Cyclosporine has been used in the renal transplantation patient for its inhibitory effect on T cell function. In more recent times, cyclosporine has been used in a number of immune-mediated disorders, including keratoconjunctivitis sicca, perianal fistula (anal furunculosis), and IMHA. Anecdotal reports suggest that cyclosporine (3-7 mg/kg PO BID) may be useful in the treatment of some cases of refractory IBD. Evidence-based medicine studies will be needed to establish efficacy, but anecdotal experience would suggest that cyclosporine may be useful in some of the more difficult or refractory cases of IBD.

2 Chlorambucil ­ Chlorambucil (2 mg/m PO every other day) has been used in place of azathioprine in some difficult or refractory cases of feline IBD.

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8. BEHAVIORAL MODIFICATION Inflammatory bowel disease and irritable bowel syndrome very likely have underlying behavioral components. Abnormal personality traits and potential environmental stress factors were identified in 38% of dogs in one study. Multiple factors were present in affected households, including travel, re-location, house construction, separation anxiety, submissive urination, noise sensitivity, and aggression.185 The role of behavior in the pathogenesis and therapy of canine and feline gastrointestinal disorders remains largely unexplored.

PROGNOSIS

Most reports indicate that the short-term prognosis for control of IBD is good to excellent. Following completion of drug therapy, many animals are able to maintain remission of signs with dietary management alone. Treatment failures are uncommon and are usually due to 1) incorrect diagnosis (it is especially important to rule out alimentary lymphosarcoma), 2) presence of severe disease such as histiocytic ulcerative colitis and protein-losing enteropathy or irreversible mucosa lesions such as fibrosis, 3) poor client compliance with appropriate drug/dietary recommendations, 4) use of inappropriate drugs or nutritional therapy, and 5) presence of concurrent disease such as small intestinal bacterial overgrowth or hepatobiliary disease. The prognosis for cure of IBD is poor, and relapses should be anticipated.

REFERENCES

A more detailed review of diseases of the intestine, including 294 references, may be found in: Washabau RJ. Diseases of the Intestine. In, Textbook of Veterinary Internal Medicine, 6th edition, Ettinger SJ and Feldman EC, editors. WB Saunders Co, Philadelphia, PA, 2005: 1378-1408.

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COMPANION ANIMAL: Gastrointestinal Issues

INFECTIOUS GASTROINTESTINAL DISORDERS IN DOGS AND CATS

Robert J. Washabau, VMD, PhD, DACVIM

Professor of Medicine and Department Chair, Department of Veterinary Clinical Sciences College of Veterinary Medicine, University of Minnesota St. Paul, MN The gastrointestinal tract may be colonized by several types of infectious organisms. The most important of these are the helminths (Trichuris spp., Ancylostoma spp., Heterobilharzia spp.), protozoa (Giardia spp., Tritrichomonas spp.), fungi (Histoplasma spp.), Oomycetes (Pythium spp.), algae (Prototheca spp.), and bacteria (Brachyspira spp., Campylobacter spp., Clostridium spp., enteropathogeneic and enterotoxigenic E. coli, and Salmonella spp.). The routine medical investigation of any dog or cat affected with chronic small or large bowel diarrhea should include direct and indirect fecal examinations for helminth and protozoa, bacterial culture of feces, and serologies. Some organisms appear to be of low pathogenicity, but it should be emphasized that even commensal organisms may become pathogens given the appropriate circumstance.

HELMINTHS

TRICHURIS ETIOLOGY Trichuris vulpis is perhaps one of the most common causes of chronic large bowel diarrhea in dogs. Cats are occasionally infected with T. serrata and T. campanula. Clinical signs in Trichuris-infected dogs and cats may vary from asymptomatic infections, to mild intermittent episodes of mucousy feces, to acute onset bloody diarrhea with tensmus and dyschezia. PATHOPHYSIOLOGY The fecal-oral route of transmission is the canonical route of infection. Following ingestion of infective Trichuris ova, eggs hatch in the small intestine and larvae migrate to the cecum and colon where they attach to the mucosa. The pathogenicity of any infection is generally related to the magnitude of the host immune response. Factors contributing to the pathogenicity and clinical signs include the number of mature worms present, the location of the worms, the degree of inflammation, the severity of anemia or hypoproteinemia, nutritional status of the host, and the presence of other gastrointestinal parasites and micro-organisms. CLINICAL EXAMINATION Affected animals generally have mild clinical signs of typhlitis and colitis, although some dogs develop a clinical scenario of signs and laboratory findings (e.g., hyponatremia, hypochloremia, hyperkalemia) consistent with hypoadrenocorticism. When tested, Trichuris-infected dogs are normo-reactive to ACTH stimulation, and are instead referred to as pseudoAddisonian. Eosinophilia, anemia, and hypoalbuminemia are possible, but these are more common laboratory findings with other gastrointestinal heminth infections, e.g., hookworms. DIAGNOSIS Trichuris ova can be identified on routine fecal flotation procedures, however they may be missed because of intermittent shedding. Empirical treatment for occult Trichuris infection should always be performed before moving on to a more detailed, costly, and unnecessary medical investigation. TREATMENT There are many safe and effective therapeutic agents for Trichuris spp. Fenbendazole, febantel with praziquantel, milbemycin, and ivermectin with pyrantel pamoate all have established efficacy against whipworms. Treatment should be repeated in three weeks and again in three months, and pet owners should be advised to de-contaminate the environment. PROGNOSIS The prognosis for recovery and cure is excellent.

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ANCYLOSTOMA CANINUM Hookworms are primary pathogens of the small intestine, but they occasionally infect the cecum and colon with overwhelming infestations. Diagnosis is achieved by demonstrating hookworm ova in the feces, and treatments are similar to those used for whipworm infections. HETEROBILHARZIA AMERICANA ETIOLOGY H. americana is considered the primary agent of schistosomiasis in dogs. It is an uncommon infection in dogs and it is encountered almost exclusively in the southern Atlantic and Gulf Coast states in the United States. In addition to the dog, nutria, raccoons, rabbits, and mice serve as important reservoir hosts. Although uncommon, heterobilharziasis is an important consideration in the differential diagnosis of acute and chronic large bowel diarrhea in endemic areas. PATHOPHYSIOLOGY The life cycle of H. Americana is complex and involves an intermediate (snail) and definitive (dog) host, and various life stages. Dogs are infected when motile cercaria from snails penetrate their skin. The schistosomulae migrate from the skin to the liver of the definitive host where they develop into mature male and female worms. Adult schistsomes lay eggs in the terminal mesenteric venules and egg migration through the bowel wall elicits an intense granulomatous response. In other words, it is the host response that gives rise to the clinical symptomatology. CLINICAL EXAMINATION Clinical signs vary from none to acute signs of vomiting, weight loss, bloody diarrhea, and progressive emaciation. Affected animals may have biochemical evidence of hypoalbuminemia, hyperglobulinemia, hypercalcemia, and liver enzyme elevation. DIAGNOSIS Diagnosis is confirmed by demonstration of ova on direct fecal examination or tissue biopsy. Serologic tests have not yet been successfully implemented in companion animals. TREATMENT Fenbendazole in combination with praziquantel appears to be effective in the treatment of H. americana. PROGNOSIS The prognosis for acute infections is generally favorable although severe liver involvement may portend chronic liver disease and cirrhosis.

PROTOZOA

Balantidium coli Balantidium coli is primarily a pathogen of sheep. Only one case report of natural infection in the dog has ever been published (Ewing 1966). In a recent report, a total of 375 fecal samples of 56 mammalian species belonging to 17 families of 4 orders were examined for the detection of Balantidium coli. B. coli organisms were detected in several animal species, but not in dogs or cats. Entamoeba histolytica There are two isolated case reports of colitis in dogs and one in cats associated with recovery of E. histolytica from the feces. E. histolytica can be recovered from the feces of healthy dogs and cats but it appears to be of low pathogenicity to dogs and cats.

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Giardia ETIOLOGY Giardia spp. are protozoal parasites that infect primarily the small intestine of dogs and cats. The cecum and colon are only occasionally colonized by Giardia. All mammalian isolates are currently classified as Giardia lamblia, athough some nomenclature systems use the name G. duodenalis or G. intestinalis. Recent DNA sequence technology suggest that there are 1 or 2 distinct Giardia genotypes that can be isolated exclusively from dogs, and a distinct genetic group that can be isolated from cats. It's not clear whether there are differences in pathogenicity between these genotypes. Giardia species have a world-wide distribution. Because Giardia is maintained in nature primarily by fecal-oral transmission, more cases are associated with crowded and unsanitary conditions. A recent study showed a prevalence in the dog of 7.2%. PATHOPHYSIOLOGY Giardia sp. are found on the surface of enterocytes where the trophozoites attach to the brush border of the epithelium. Specific histologic changes have not been reported but persistence of infection may promote apoptosis and inhibition of reepithelialization. CLINICAL EXAMINATION Although infected animals may remain asymptomatic, clinical signs such as acute or chronic diarrhea, weight loss, or even acute or chronic vomiting may develop. Although Giardia cysts and trophozoites have been found in the feces of dogs with both small bowel and large bowel diarrhea, Giardia infection is primarily a problem of the small intestine. DIAGNOSIS Giardia infections can be diagnosed by demonstrating motile trophozoites on fresh fecal smears, or cysts by zinc sulfate sedimentation. Commerical ELISA kits have also been used to detect Giardia antigen in fresh fecal samples. ELISA assays may be slightly more sensitive and specific than a single zinc sulfate concentrating technique in diagnosing Giardia infections in dogs. A direct immuofluorescent antibody test has been used in the diagnosis of Giardia infections in humans, but it has not yet been validated in the dog. Duodenal aspirates during gastrointestinal endoscopy appear to be ineffective in diagnosing Giardia infection. TREATMENT Metronidazole, ipronidazole, fenbendazole, albendazole, and a praziquantel, pyrantel pamoate, febantel combination have all been used in the treatment of Giardia infections with varying levels of success. A Giardia vaccine has been shown to be effective in prevention and therapy in dogs, but efficacy has not yet been established in cats. PROGNOSIS The prognosis for longterm health and recovery is generally very favorable. Isospora canis, I. ohioensis, I. felis, I. neorivolta The Isospora species are the most common coccidial parasites of dogs (I. canis and I. ohioensis) and cats (I. felis and I. neorivolta). The coccidia are primarily parasites of the small intestine, but I. ohioensis may induce cecal and colonic pathology in puppies and young dogs. Sulfadimethoxine (50 mg/kg PO SID for 10 days) or sulfatrimethoprim (15-30 mg/kg PO SID for 5 days) may be used where clinical signs warrant treatment.

TRITRICHOMAS FOETUS ETIOLOGY Tritrichomonas foetus is a flagellated protozoan parasite that is an important venereal pathogen in cattle. T. foetus has also been identified as an intestinal pathogen in domestic cats from which intraluminal infection of the colon leads to chronic large bowel diarrhea. Infected cats are usually young and frequently reside in densely populated housing such as catteries or animal shelters. Cats often have a history of infection with Giardia spp; these infections are subsequently identified as trichomoniasis after failure to eradicate the organisms with standard antiprotozoal treatment (e.g., metronidazole or fenbendazole).

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PATHOPHYSIOLOGY After experimental inoculation in cats, T. foetus organisms have been shown to colonize the ileum, cecum, and colon, reside in close contact with the epithelium, and are associated with transient diarrhea that is exacerbated by co-existing cryptosporidiosis. CLINICAL EXAMINATION Infected animals have clinical signs that are consistent with chronic colitis-type diarrhea. DIAGNOSIS Diagnosis of trichomonosis in cats is made by direct observation of trichomonads in samples of freshly voided feces that are suspended in physiologic saline (0.9% NaCl) solution and examined microscopically at 200 to 400x magnification. Tritrichomonas foetus can also be grown from feces via incubation at 37 °C in Diamond's medium, although this test is not yet commercially available. The sensitivity of direct examination of a fecal smear for diagnosis of T. foetus in naturally infected cats is unknown but is suspected to be poor. A commercially available culture system that is sensitive and specific for culture of T foetus will improve the diagnostic outcome. These kits are most useful when inoculated with 0.1 grams of fresh feces at 25 °C. More recently, a single-nested tube PCR technique has been developed that is ideally suited for diagnostic testing of feline fecal samples that are found negative by direct microscopy and definitive identification of microscopically observable or cultivated organisms. TREATMENT At this time time, the origin of the infection in most cats is unknown, and there is no effective antimicrobial treatment for T foetus infection. Metronidazole and fenbendazole may improve clinical signs but generally do not resolve infection. Nitazoxanide eliminates shedding of T. foetus and Cryptosporidia oocysts but diarrhea and oocyst shedding recur with discontinuation of treatment. A series of cats that were treated with paromomycin for T. foetus infection subsequently developed kidney failure. Consequently, paromomycin should probably not be used in cats. PROGNOSIS The prognosis for eradication of the organism is not encouraging at this time.

FUNGI

HISTOPLASMA CAPSULATUM ETIOLOGY Histoplasmosis is a systemic fungal disease of dogs and cats caused by Histoplasma capsulatum. In the environment, H. histoplasma organisms are mycelial, saprophytic soil fungi. In infected tissue or when cultured at 30 to 37 °C, the organism is a yeast. The fungus is endemic throughout most of the temperate and subtropical regions of the world. Most cases of histoplasmosis in the United States occur in the central states, with the geographic distribution following the Mississippi, Ohio, and Missouri Rivers. PATHOPHYSIOLOGY Infection is probably via inhalation or ingestion of infective conidia from the environment. The respiratory system is thought to be the primary route of infection in cats and dogs, although the gastrointestinal tract may also be an important route in the dog. After inhalation or ingestion, conidia transform from the mycelial phase and are phagocytized by macrophages, where they grow as facultative intracellular organisms. Hematogenous and lymphatic dissemination results in multisystemic disease. Organisms can be disseminated to any organ system, but the lungs, gastrointestinal tract, lymph nodes, liver, spleen, bone marrow, eyes, and adrenal glands are the most common organs of dissemination in the dogs; lungs, liver, lymph nodes, eyes, and bone marrow are most commonly affected in cats. Cell-mediated immunity induces a granulomatous inflammatory response in most infection. CLINICAL EXAMINATION Dogs with gastrointestinal histoplasmosis are typically presented with mild fever, anorexia, lethargy, weight loss, vomiting, diarrhea, hematochezia, and tenesmus. Cachexia is a common physical examination finding. Other historical and physical

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examination findings (dyspnea, cough, ascites, lameness, oropharyngeal ulcerations, chorioretinitis, neuropathy) will depend upon organ and tissue involvement. DIAGNOSIS Organism identification is required for definitive diagnosis. The most common means of organism identification is cytology. Cytology from affected tissue reveals pyogranulomatous inflammation, often with numerous small, round to oval intracellular yeast cells (2-4 m in diameter) characterized by a basophilic center and a light halo. Exfoliative cytology during colonoscopy is particularly useful in diagnosing the disease. Histopathology is helpful if cytology is non-diagnostic or inconclusive. Multiple endoscopic colonic biopsies are usually sufficient to diagnose the disease. The yeast form does not stain well with routine hematoxylin-eosin stains, so special stains such as PAS and Gomori's methenamine silver stain are often used to demonstrate organisms. Fungal culture from affected tissue can be used for diagnosis but is rarely needed in clinical cases. Currently available serologies have poor specificity and sensitivity. TREATMENT Itraconazole (5 mg/kg PO BID for two to four months) is considered the treatment of choice for feline histoplasmosis. In one study, itraconazole therapy cured histoplasmosis infections in all eight study cats. Ketoconazole and amphotericin B have been described as the treatments of choice for canine histoplasmosis. With colonic involvement, additional gastrointestinal therapy may be useful in affected dogs, e.g., dietary modification, treatment for small intestinal bacterial overgrowth, and direct anti-diarrheal theapy. Corticosteroids may have been used successfully in the treatment of airway obstruction secondary to hilar lymphadenopathy in chronically infected dogs. PROGNOSIS There may be important species differences in prognosis although the paucity of reports, especially of prospective clinical trials, makes it difficult to generalize. It would seem that the prognosis is guarded in dogs, but fair to good in cats.

OOMYCETES

PYTHIUM INSIDIOSUM ETIOLOGY Pythium insidiosum is an aquatic oomycete that causes severe gastrointestinal pathology in a range of hosts in the tropical and subtropical climates. Based on ribosomal RNA gene sequence data, members of the Class Oomycetes are phylogenetically distinct from the Kingdom Fungi, and are more closely related to algae than to fungi. The oomycetes differ from fungi in two important properties, i.e., cell wall and cell membrane composition. Chitin is an essential component of the fungal cell wall, but it is generally lacking in the oomycete cell wall. Oomycetes also differ from fungi in that ergosterol is not a principal sterol in the oomycete cell membrane. This difference may explain why ergosterol-targeting drugs like itraconazole are less effective in the medical treatment of pythiosis. PATHOPHYSIOLOGY The infective state of P insidiosum is thought to be the motile zoospore, which is released into stagnant water in warm environments, and likely causes infection either by encysting in the skin, or by being ingested into the gastrointestinal tract. Ingested zoospores encyst and adhere to the gastric, jejunal, and colonic epithelium with a polarity oriented toward the submucosa for rapid tissue penetration following germ tube eruption. Pythium induces a chronic pyogranulomatous response in the gastrointestinal tract and mesenteric lymph nodes. The gastric outflow tract and ileocolonic junction are the most frequently affected portions of the G.I. tract, and it is not uncommon to find two or more segmental lesions in the same patient. Inflammation in affected regions is typically centered on the submucosa, with variable mucosal ulceration and occasional extension of disease through serosal surfaces, resulting in adhesion formation and peritonitis. CLINICAL EXAMINATION Weight loss, vomiting, diarrhea, and hematochezia are the most important clinical signs. Physical examination often reveals emaciated body condition and a palpable abdominal mass. Signs of systemic illness such as lethargy and depression are not typically present unless intestinal obstruction, infarction, or perforation occurs.

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DIAGNOSIS Ileocolonic wall thickening, obliteration of the normal layered appearance, and regional lymphadenopathy are common ultrasonographic features of canine intestinal pythiosis. Of course, these findings cannot be readily differentiated from those associated with intestinal malignancy. Definitive diagnosis requires histologic demonstration or immunohistochemical staining of the organism and/or positive ELISA or PCR assays. The histologic findings associated with pythiosis generally are characterized by eosinophilic granulomatous to pyogranulomatous inflammation with fibrosis. Affected tissue typically contain multiple foci of necrosis surrounded and infiltrated by neutrophils, eosinophils, and macrophages. Discrete granulomas composed of epithelioid macrophages, plasma cells, multinucleate giant cells, and neutrophils and eosinophils may also be observed. Pythium zoospores may be cultured directly from affected tissue in antibiotic-containing (e.g., streptomycin and ampicillin) media. More recently, sensitive and specific ELISA and PCR assays have been developed for the accurate diagnosis of pythiosis in dogs. TREATMENT Aggressive surgical resection remains the treatment of choice for pythiosis in dogs. Because it provides the best opportunity for long-term cure, complete resection of infected tissue should be pursued whenever possible. Segmental lesions of the G.I. tract should be resected with 3 to 4 cm margins whenever possible. Medical therapy for the oomycetes has not been very promising. This may relate to the absence of ergosterol (cell membrane target of most currently available anti-fungal drugs) in the oomycete cell membrane. Clinical and serologic cures have been obtained in a small number of dogs following therapy with amphothericin B lipid complex (2-3 mg/kg QOD administered to a cumulative dose of 24-27 mg/kg) or itraconazole (10 mg/kg a 24 hrs for 6 to 9 months).

PROGNOSIS Unfortunately, most dogs with G.I. pythiosis are not presented to the veterinarian until late in the course of the disease, when complete excision is not possible. The anatomic site of the lesion (e.g., pylorus or ileocolic sphincter) may also prevent complete excision. Consequently, the prognosis is usually grave in most animals.

ALGAE

PROTOTHECA ZOPFII/WICKERHAMII ETIOLOGY Three species have been recognized within the genus Prototheca: P. stagnosa, P. wickerhamii, and P. zopfii, and a fourth species, P. salmonis, has been proposed. Of these three species, P. wickerhamii and P. zopfii have demonstrated pathogenicity. Prototheca spp.are ubiquitous in nature and are found in sewage systems, soil, lakes, rivers, and ponds, and in feces. The organism has been documented to cause disease in dogs and cats and a variety of other species. P. wickerhamii is the causative organism in virtually all instances of cutaneous protothecosis, and P. zopfii is the causative organism in most instances of disseminated disease. PATHOPHYSIOLOGY Cutaneous infection with granuloma formation is the most common manifestation of protothecosis in most species, including cats and humans. Dissemination does not readily occur in cats or humans, but the infection readily disseminates to distant sites in dogs. CLINICAL EXAMINATION Of the 26 canine cases reported in the veterinary literature, 20 either presented with or developed ocular signs. Sixteen cases had gastrointestinal signs, usually colitis-type diarrhea, vomiting, and weight loss. Six cases had neurologic signs in the form of paresis, head tilt, cervical pain, circling, and ataxia. P. zopfii accounts for most of the cases of canine disseminated protothecosis. DIAGNOSIS Contrast radiography or abdominal ultrasonography may reveal diffuse colonic wall thickening or obstruction, but these are non-specific findings. Fecal parasitologic examination is generally of little use in demonstrating the organism, but

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exfoliative cytology and/or histology readily identifies the organism. Aqueous or vitreous centesis can also be performed in dogs with ocular pathology and is generally useful in documenting organisms in the ocular fluid. TREATMENT The management of systemic protothecosis has been challenging in all animal species. Amphotericin B and itraconazole (5 mg/kg PO BID for one month and then 5 mg/kg PO SID thereafter) have been used in several patients. Short term improvement was reported in only two dogs. PROGNOSIS Like pythiosis, the prognosis for protothecosis is grave. The course of the disease is so insidious that, by the time a definitive diagnosis has been reached, the organism has often disseminated throughout the body.

BACTERIA

BRACHYSPIRA PILOSICOLI ETIOLOGY Brachyspira spp., formerly Serpulina spp. or Treponema spp., are intestinal spirochetes of dogs, pigs, guinea pigs, rodents, non-human primates, and humans. In pigs, they cause two important diarrheal syndromes: B. hyodysenteriae causes swine dysentery and B. pilosicoli causes porcine intestinal spirochetosis. The consequences of colonization by intestinal spirochetes in animals other than pigs and in humans is controversial. Some investigators believe the bacteria may be responsible for various gastrointestinal disturbances, while others have questioned their clinical importance and claimed that shedding of large numbers of spirochetes in conncection with diarrhea may be blamed on dislodgment from the crypts by diarrhea induced by other causative agents. Intestinal spirochetes have been found in both healthy and diarrheal dogs. In a recent study it was suggested that canine intestinal spirochetes consist of B. pilosicoli and a group of non-pathogenic spirochetes, provisionally designated Brachyspira (Serpulina) canis. Infection with B. pilosicoli in the colon of dogs might be subclinical, but massive infection, which may occur in environiments with poor hygiene or in dogs with a compromised intestinal function because of concurrent etiological factors, may cause diarrhea. B. pilosicoli may be associated with diarrhea in colony and pet shop dogs. PATHOPHYSIOLOGY Severity of clinical signs appears to be associated with attachment of spirochetes to the epithelial surface of the colon, persistence of B. pilosicoli in the cecal and colonic crypt lumina, chronic inflammation caused by spriochetal invasion into the lamina propria, and translocation to extraintestinal sites. CLINICAL EXAMINATION Infected animals have clinical signs consistent with colitis-type diarrhea. DIAGNOSIS Brachyspira infections can be diagnosed by fecal culture, colonic histopathology, and PCR of fresh fecal samples. Brachyspira spp. are most effectively grown on either trypticase soy agar with 5% sheep blood or selective BJ agar at 42 °C under anaerobic conditions. PCR amplification of the 16S rRNA gene has been used to further clarify natural infections. TREATMENT The best treatments for Brachspira spp. infection have not yet been identified. PROGNOSIS - The prognosis for health and recovery appears to be quite favorable.

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CAMPYLOBACTER ETIOLOGY Campylobacter jejuni, C. coli, C. upsaliensis, and C. helveticus are commensal organisms found in the gastrointestinal tract of healthy dogs and cats throughout the world. The high prevalence of these organisms in healthy non-diarrheic dogs (C. jejuni ­ 49%; C. coli ­ 5%; C. upsaliensis ­ 19%) and cats (C. jejuni ­ 46%; C. coli ­ 1%; C. upsaliensis ­ 5%; C. helveticus ­ 22%) complicates diagnosis. Under certain conditions, however, Campylobacter can induce significant gastrointestinal tract pathology. Young age, immunoincompetence, concurrent gastrointestinal infections, prior therapeutic interventions (e.g., antibiotics), and poor hygienic conditions appear to be the greatest risk factors for the development of infection. PATHOPHYSIOLOGY At some point, Campylobacter organisms become enteroinvasive and induce the host inflammatory response. C. jejuni localizes in mucus-filled crypts of the intestine and colon where it induces a superficial erosive enterocolitis. Colonic epithelial glands undergo hyperplasia and thickening with exfoliation of the brush border and goblet cells. The colonic epithelium becomes cuboidal, crypt height is reduced, and crypt abscess are present. Shallow crypts and blunt irregular villi are features of the ileum response to infection. CLINICAL EXAMINATION Clinical signs are watery diarrhea, often containing mucous and blood pigments, tenesmus, anorexia, fever, and vomiting. Concurrent infections with Salmonella, Giardia, or parvovirus cause more severe disease. DIAGNOSIS Direct examination of a fresh fecal sample is the method of diagnosis in many instances. Large numbers of curved, highly motile bacteria along with increased numbers of leukocytes is presumptive evidence of Campylobacter infection. With Gram staining, large numbers of faintly staining Gram-negative, slender, curved (gull-wing shaped) rods are evident. Fecal cultures or PCR are the most conclusive ways to determine the presence of Campylobacter. C jejuni is best cultured microaerophilically at 42 °C for 48 hours on special Campylobacter blood agar plates. TREATMENT Erythromycin is the treatment of choice, although tetracyclines, aminoglycosides, clindamycin, and quinolones are also effective. Post-treatment cultures should be performed to confirm eradication. Pet owners should be advised on the importance of proper hygiene. PROGNOSIS The prognosis for recovery and cure are generally excellent unless an underlying immunosuppressive condition has increased the susceptibility to infection.

CLOSTRIDIUM PERFRINGENS ETIOLOGY C. perfringens is a Gram-positive, spore-forming, obligate anaerobic rod-shaped bacterium that contributes to the microbial ecology and nutrition of the colon in healthy dogs and cats. Under certain conditions, proliferation and sporulation of C. perfringens permits enterotoxin A (or CPE) production which may then induce mucosal damage, fluid secretion and large bowel-type diarrhea. Evidence for and against a role for C. perfringens in the pathogenesis of large bowel diarrhea has been put forward. Enterotoxigenic C. perfringens has been associated with canine nosocomial diarrhea, hemorrhagic enteritis, and acute and chronic large bowel diarrhea. On the other hand, many dogs harbor C. perfringens and CPE in the gastrointesintal tract without developing clinical signs. Until more definitive evidence is obtained, including the fulfillment of Koch's postulates, C. perfringens should be considered as a suspected pathogen in large bowel diarrhea. PATHOPHYSIOLOGY The presumed pathogenicity of C. perfringens requires an anaerobic environment, sporulation, and enterotoxin production. There are problems with this hypothesis ­ enterotoxin may be demonstrated in the feces without sporulation, and

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enterotoxin may be found in the feces of healthy dogs. C. perfringens isolates are classified as 1 of 5 toxigenic types (A-E) based on the production of 1 or more of 4 major (, , , ) and 7 minor (, , , , , , and sialidase) toxins. Although all 5 types of C. perfringens are capable of producing CPE, the majority is produced by type A strains. As with enterotoxigenic E. coli (ETEC) strains, CPE is believed to induce crypt epithelial cell secretion. CLINICAL EXAMINATION Clostridium perfringens-associated colitis is believed to be a major cause of acute, nosocomial as well as chronic large bowel diarrhea. Acute nosocomial diarrhea often begins within 1 to 5 days of boarding or kenneling. Affected dogs develop diarrhea often with blood pigments, mucous, and tenesmus. These diarrheas are usually self-limiting and may resolve with supportive care alone. Chronic large bowel diarrheas associated with C. perfringens are similar to other colitis-type diarrheas, i.e., chronic, intermittent, and recurring signs of colitis. DIAGNOSIS There is no gold standard for the diagnosis of C. perfringens-associated diarrhea. Ideally, the diagnosis would be made on the basis of positive test results with Gram staining, fecal culture, ELISA enterotoxin (CPE) assay, PCR enterotoxin (cpe) genotyping, and rule-out of other colonic diseases on colonoscopy and biopsy. Compared to normal dogs (without diarrhea), diarrheic dogs are more often CPE ELISA and cpe PCR positive, but many normal dogs are positive on both assays. TREATMENT Recent in vitro antimicrobial susceptibility testing suggests that C. perfringens should be susceptible to ampicillin, erythromycin, metronidazole, and tylosin. These antibiotics have also been used in vivo with great success. It should be emphasized many of the same patients respond to supportive care, including intravenous fluids, intestinal protectants, and bland or fiber-supplemented diets. PROGNOSIS Affected animals usually respond to appropriate therapy within a matter of days. The prognosis for recovery is excellent.

CLOSTRIDIUM DIFFICILE Clostridium difficile is believed to share many ecological factors with Clostrium perfringens, but the role of this organism as a pathogen in dogs and cats has not been firmly established. Compared to normal dogs (without diarrhea), diarrheic dogs are more often toxin A ELISA positive even though they are toxin A PCR negative. As with C. perfringens, many healthy dogs and cats carry C. difficile without developing clinical signs. In one recent study, it was difficult to experimentally infect dogs with this organism, and those that were infected did not develop clinical signs. Antibiotic-associated diarrheas develop in dogs and cats but they may have a pathogenesis other than C. difficile. ESCHERICHIA COLI ETIOLOGY Most strains of E. coli are true commensal organisms that are not associated with clinical signs. Strains of Escherichia coli that cause diarrhea in animals can be grouped into five main categories: enterotoxigenic (ETEC), enteroinvasive (EIEC), enteropathogenic (EPEC), enterohemorrhagic (EHEC), and enteroadherent (EAEC) organisms (Levine 1987). Identification of pathogenic strains requires modern molecular technology such as bioassays, DNA hybridization, and PCR ampflication. PATHOPHYSIOLOGY Infection may result in enteritis, colitis, or both. Enterotoxigenic (ETEC) strains adhere to the surface of epithelial cells and produce heat-labile and/or heat-stable toxins that induce crypt epithelial cell secretion. Enteroinvasive (EIEC) strains of E. coli invade, replicate in, and destroy epithelial cells. Enteropathogenic (EPEC) strains are neither enterotoxigenic nor enteroinvasive, but they do attach to and efface the brush border of the enterocytes. Enterohemorrhagic (EHEC) strains produce verocytotoxins that induce hemorrhagic ileitis and colitis. Enteroadherent (EAEC) strains of E. coli also induce enterocyte pathology, but their mechanism of action is poorly understood. Enterotoxigenic, enteropathogenic, and enterohemorrhagic E. coli have all been isolated from dogs and cats with diarrhea. E. coli endotoxin colonic absorption of water and sodium and contributes to the diarrhea seen during and after episodes of sepsis.

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CLINICAL EXAMINATION Affected animals typically have diarrhea and hematochezia with clinical signs relevant to the small intestine, colon, or both. DIAGNOSIS E. coli can be grown from essentially all dog and cat feces, so a positive culture does not necessarily reveal the identity of an underlying pathogen. In addition to positive culture, diagnosis may require enterotoxin assays, and DNA hybridization and PCR amplification. TREATMENT Antibiotics should be used only in those cases in which there is firm evidence of bacterial infection. Fluorquinolones appear to be a very effective classification for the treatment of enteric E. coli infections. PROGNOSIS The prognosis is generally good for recovery and cure if infection is recognized early in the clinical course. SALMONELLA ETIOLOGY Salmonella spp. are predominantly motile, Gram-negative facultative anaerobic rod-shaped bacteria found in the feces of normal and diarrheic animals. As with many other commensal organisms of the gastrointestinal tract, the high prevalence of these organisms complicates diagnosis. From 1% to 30% of the fecal samples or rectal swabs taken from healthy domestic pet dogs, 16.7% of dogs boarded in kennels, and 21.5% of hospitalized dogs were found to be positive on bacteriological culture for Salmonella. From 1% to 18% of healthy cats and 10.6% of random source research colony cats are also culture-positive for Salmonella. Despite these findings, several species of Salmonella have been impugned in the pathogenesis of acute enterocolitis in dogs and cats. S. typhimurium is the species most commonly isolated from diarrheic feces of dogs and cats, although other species have been identified. PATHOPHYSIOLOGY Those most at risk for Salmonella infection are young and immunoincompetent animals, those with concurrent gastrointestinal infections (e.g., parvoviral or parasitic infections), and those animals who have had prior therapeutic interventions (e.g., antibiotics or glucocorticoids). Salmonella is an enteroinvasive organism that induces an acute inflammatory response resulting in enterocolitis, mucosal sloughing, and secretory diarrhea. Most Salmonella infections are resolved via the local immune response, but bacterial translocation and septicemia may evolve into systemic inflammatory response (SIRS) and multiple organ dysfunction syndromes (MODS) in some patients. Early recognition is important in preventing this sequela. CLINICAL EXAMINATION The main clinical signs of Salmonella enterocolitis are anorexia, lethargy, fever, vomiting, diarrhea with mucous and blood pigments, dehydration, abdominal pain, and tenesmus. With bacterial translocation and septicemia, affected animals may have evidence of pale mucous membranes, weakness, tachycardia, tachypnea, and vacular collapse. DIAGNOSIS Culture, serotyping, and PCR are the best methods of diagnosing Salmonella infections. TREATMENT Treatment varies according to the severity of the clinical signs. Mild, self-limiting forms of enterocolitis may in fact resolve with little more than supportive therapy. Antitbiotic therapy in such cases may prolong fecal shedding and encourage development of the carrier state. In animals with severe hemorrhagic diarrhea, history of immunosuppression, suspected or documented septicemia, and/or evidence of SIRS, parenteral antibiotics should definitely be used. If culture results are unavailable, therapy should include enrofloxacin, amoxicillin, or trimethoprim-sulfa, all of which are effective against Salmonella. Post-treatment cultures should be performed to confirm eradication, and pet owners should be advised of the public health importance of the disease.

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PROGNOSIS The prognosis for recovery in non-septicemic patients is generally good, although some animals may remain chronic carriers with recrudescence during periods of stress or unrelated disease. The prognosis for the septicemic patient is more guarded. YERSINIA ENTEROCOLITICA Y. enterocolitica is a commensal organism of the gastrointestinal tract of some dogs and cats that may be a rare cause of acute colitis. It is a motile, Gram-negative facultative anaerobic coccobacillus bacterium that may be transmitted to animals via ingestion of raw pork or contaminated water. If suspected, animals should be treated with cephalosporins or trimethoprim-sulfa. The prognosis is unknown because of the paucity of case reports.

REFERENCES

Washabau RJ. Diseases of the Intestine. In, Textbook of Veterinary Internal Medicine, 6th edition, Ettinger SJ and Feldman EC, editors. WB Saunders Co, Philadelphia, PA, 2005: 1378-1408.

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COMPANION ANIMAL: Gastrointestinal Issues

FELINE EXOCRINE PANCREATIC DISEASE: A DIAGNOSTIC AND THERAPEUTIC CHALLENGE

Robert J. Washabau, VMD, PhD, DACVIM

Professor of Medicine and Department Chair, Department of Veterinary Clinical Sciences College of Veterinary Medicine, University of Minnesota St. Paul, MN

Acute necrotizing pancreatitis is but one of many pathologies involving the feline exocrine pancreas. Based on a series of reports over the past decade,1-11 we now have a much better understanding of the natural history of these diseases. A pathologic classification of feline exocrine pancreatic disease has been used to delineate these disorders although it should be emphasized that significant overlap exists between several disease categories, particularly with regard to acute and chronic forms of pancreatitis. ACUTE NECROTIZING PANCREATITIS (ANP) - This lesion is characterized by pancreatic acinar cell and peri-pancreatic fat necrosis (>50% of the pathology), with varying amounts of inflammation, hemorrhage, mineralization, and fibrosis. Inflammation may be present, but necrosis is the predominant feature. Reports of this condition were uncommon prior to the early 1990's, probably related to difficulties in diagnosis as well as lower incidence of disease. ANP is now a well1-10 recognized gastrointestinal disorder of significant morbidity and mortality in the domestic cat. ACUTE SUPPURATIVE PANCREATITIS (ASP) - Acute suppurative pancreatitis differs from acute necrotizing pancreatitis in that neutrophilic inflammation accounts for >50% of the pancreatic pathology. Necrosis may be present, but neutrophilic inflammation is the predominant feature. ASP is less common than ANP, appears to affect younger animals, and may have a differing pathogenesis.2,5,6,10 CHRONIC NON-SUPPURATIVE PANCREATITIS (CP) - This lesion is characterized by lymphocytic inflammation, fibrosis, and acinar atrophy. Necrosis and suppuration may be present in small amounts, but lymphocyte infiltration is the predominant feature. Ante-mortem differentiation of CP and APN cannot be made on the basis of clinical, clinicopathologic, or imaging findings;10 histopathology remains the only dependable method of differentiating these two disorders.10 Chronic nonsuppurative pancreatitis and acute necrotizing pancreatitis may vary in their pathogeneses or they may represent a continuum of disease from necrosis to inflammation and fibrosis.1,10 PANCREATIC NODULAR HYPERPLASIA - Nodules of pancreatic acinar or duct tissue are distributed throughout the pancreatic parenchyma. Fibrosis, inflammation, necrosis, and hemorrhage are not features of this condition. The clinical significance of this lesion is unknown. Pancreatic nodular hyperplasia is often detected at the time of routine abdominal ultrasonography or as an incidental finding at necropsy. Its importance appears to reside in the need to differentiate its ultrasonographic characteristics from those of acute necrotizing pancreatitis. PANCREATIC NEOPLASIA - Neoplastic disorders of the pancreas may be primary (e.g., adenoma, adenocarcinoma) or secondary, and they are classified as benign or malignant. Pancreatic adenocarcinoma is the most common malignancy of the feline exocrine pancreas and is of ductal (primarily) or acinar origin. Neoplastic infiltration may be accompanied by necrosis, inflammation, fibrosis, hemorrhage, or mineralization in some instances. PANCREATIC PSEUDOCYST - Pancreatic pseudocyst is a common complication of pancreatitis in humans, and a not-so12 common complication in cats and dogs. Pancreatic pseuodcyst is a non-epithelial lined cavitary structure containing fluid, pancreatic cells, and/or enzyme. It is observed at the time of ultrasound, CT scan, surgery, or necropsy. Its importance appears to reside in the need to differentiate its ultrasonographic characteristics from those of pancreatic abscessation.

PANCREATIC ABSCESS - Pancreatic abscess is a circumscribed collection of purulent material involving the right or left lobe of the pancreas. Like pseudocyst, pancreatic abscessation appears to be a complication of pancreatitis in humans and

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dogs.13 The incidence and significance of this lesion in the cat are unknown. Medical and surgical therapies have been used to manage pancreatic abscesses in the dog. PANCREATIC ATROPHY - Atrophy may result from degeneration, involution, necrosis, or apoptosis of the exocrine portion of the gland. Most feline cases are believed to represent the end stage of chronic pancreatitis. The endocrine portion of the gland may or may not be involved in the same process. Exocrine pancreatic insufficiency is the clinical syndrome that results from 95% or greater loss of exocrine pancreatic function. Affected animals develop a classic maldigestion syndrome characterized by weight loss, steatorrhea, and diarrhea.11

ETIOLOGY

The etiologies of acute necrotizing pancreatitis are probably not yet completely recognized. Biliary tract disease, gastrointestinal tract disease, ischemia, pancreatic ductal obstruction, infection, trauma, organophosphate poisoning, and lipodystrophy all have known associations with the development of acute necrotizing pancreatitis in the cat. Hypercalcemia, idiosyncratic drug reactions, and nutritional causes are suggested but poorly documented causes of the disease. CONCURRENT BILIARY TRACT DISEASE - Concurrent biliary tract pathology has a known association with acute necrotizing pancreatitis in the cat. Cholangitis is the most important type of biliary tract disease for which an association has been 14 2,9 made, but other forms of biliary tract pathology (e.g., stricture, neoplasia, and calculus) have known associations. 14 Epidemiologic studies have shown that cats affected with suppurative cholangitis have significantly increased risk for pancreatitis. The pathogenesis underlying this association is not entirely clear but relates partly to the anatomic and functional relationship between the major pancreatic duct and common bile duct in this species.15,16 Unlike the dog, the feline pancreaticobiliary sphincter is a common physiological and anatomic channel at the duodenal papilla. Mechanical or functional obstruction to this common duct readily permits bile reflux into the pancreatic ductal system. Bile salt perfusion (e.g., 1-15 mM sodium cholate or glycodeoxycholate) of the major pancreatic duct induces changes in the permeability of the pancreatic duct,17,18 and sustained elevations in ductal pressure (> 40 cm H20) and bacterial infection induce pancreatic acinar necrosis.18 Ductal pressures are readily increased by biliary infection, and ductal compression is a predictable consequence of sustained ductal hypertension and pancreatic interstitial edema.18,19 CONCURRENT GASTROINTESTINAL TRACT DISEASE - Like concurrent biliary tract disease, inflammatory bowel disease (IBD) is an important risk factor for the development of acute necrotizing pancreatitis in the cat.14,20 Several factors appear to contribute to this association: (1) High incidence of inflammatory bowel disease ­ IBD is a common disorder in the domestic cat.20-22 In some veterinary hospitals and specialty referral centers, IBD is the most common gastrointestinal disorder in cats. (2) Clinical symptomatology of IBD ­ Vomiting is the most important clinical sign in cats affected with IBD.20-22 Chronic vomiting raises intra-duodenal pressure and increases the likelihood of pancreaticobiliary reflux. (3) Pancreaticobiliary anatomy ­ The pancreaticobiliary sphincter is a common physiological and anatomic channel at the duodenal papilla,15,16 thus reflux of duodenal contents would perfuse pancreatic and biliary ductal systems. (4) Intestinal Microflora ­ Compared to dogs, cats have a much higher concentration of aerobic, anaerobic and total (109 vs. 104 organisms/ml) bacteria in the proximal small intestine.23,24 Bacteria readily proliferate in the feline small intestine because of differences in gastrointestinal motility and immunology.25,26 If chronic vomiting with IBD permits pancreaticobiliary reflux, a duodenal fluid containing a mixed population of bacteria, bile salts, and activated pancreatic enzyme would perfuse the pancreatic and biliary ductal systems.27 ISCHEMIA - Ischemia (e.g., hypotension, cardiac disease) is a cause or consequence of obstructive pancreatitis in the cat. Inflammation and edema reduce the elasticity and distensibility of the pancreas during secretory stimulation. Sustained inflammation increases pancreatic interstitial and ductal pressure which serves to further reduce pancreatic blood flow, organ pH, and tissue viability.28-30 Acidic metabolites accumulate within the pancreas because of impaired blood flow.30-32 Ductal decompression has been shown to restore pancreatic blood flow, tissue pH, and acinar cell function.31,32 PANCREATIC DUCTAL OBSTRUCTION - Obstruction of the pancreatic duct (e.g., neoplasia, pancreatic flukes, calculi, and duodenal foreign bodies) is associated with the development of acute necrotizing pancreatitis in some cases.9,33 Pancreatic ductal obstruction has marked effects on pancreatic acinar cell function. During ductal obstruction, ductal pressure exceeds exocytosis pressure and causes pancreatic lysosomal hydrolases to co-localize with digestive enzyme zymogens within the

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acinar cell.34 Co-localization is the underlying pathogenesis for digestive enzyme activation within the acinar cell because lysosomal enzymes (e.g., cathepsin B) readily activate trypsin.34 INFECTION - Infectious agents have been implicated in the pathogenesis of feline acute necrotizing pancreatitis although none have been reported as important causes of ANP in any of the recent clinical case series.1-10 The pancreas is readily colonized by Toxoplasma gondii organisms during the acute phase of infection.35 In one survey of T. gondii-infected cats, organisms were found in 84% of the cases, although organ pathology was more severe in other organ systems.35 Feline herpesvirus I and feline infectious peritonitis viruses have been implicated as causative agents in several case reports,36 and feline parvoviral infection has been associated with viral inclusion bodies and pancreatic acinar cell necrosis in young kittens.37 Pancreatic (Eurytrema procyonis) and liver fluke (Amphimerus pseudofelineus, Opisthorchis felineus) infections are known causes of feline acute necrotizing pancreatitis in the southeastern United States and Caribbean Basin.33,38 Recent reports of virulent calici viral infections have been reported in multiple cat households or research facilities. Affected cats manifest high fever, anorexia, labored respirations, oral ulceration, facial and limb edema, icterus, and severe pancreatitis.39-41 Caliciviral infection has not been reported in any of the recent clinical case series of feline acute necrotizing pancreatitis,1-10 but some cases of active infection could have been overlooked. The importance of calicivirus infection in the pathogenesis of feline acute pancreatic necrosis remains to be determined. TRAUMA - Automobile and fall (`high rise syndrome") injuries have been associated with the development of acute necrotizing pancreatitis in a small number of cases.42,43 These tend to be isolated cases that do not show up as important causes in clinical case surveys. ORGANOPHOSPHATE POISONING - Organophosphate poisoning is a known cause of acute necrotizing pancreatitis in humans and dogs,44 and several cases have been reported in the cat.2 In one survey, several cats developed ANP following Diminishing treatment for ectoparasites, and two cats developed ANP following treatment with fenthion.2 organophosphate usage will probably lead to a reduced incidence of this lesion. LIPODYSTROPHY - Lipodystrophy has been cited as an occasional cause of acute necrotizing pancreatitis in the cat,45 but it has not been reported in any of the large clinical case series. HYPERCALCEMIA - Acute necrotizing pancreatitis develops in association with the hypercalcemia of primary hyperparathyroidism and humoral hypercalcemia of malignancy in humans, and a weak association with hypercalcemia has been reported in dogs.12 Moderate hypercalcemia was found as a pre-existing laboratory finding in 10% of the cases of fatal canine acute pancreatitis.12 Acute experimental hypercalcemia does indeed cause acute pancreatic necrosis and pancreatitis in cats,46,47 but it is probably not very clinically relevant. Acute hypercalcemia is an uncommon clinical finding in feline practice. Chronic hypercalcemia, a more clinically relevant condition, is not associated with changes in pancreatic morphology or function.48 IDIOSYNCRATIC DRUG REACTIONS - Therapy with azathioprine, l-asparaginase, potassium bromide and trimethoprim sulfa drugs have been associated with the development of acute necrotizing pancreatitis in the dog.12,49 Similar associations have not been made in the cat. Glucocorticoid administration has been suggested as a cause of acute pancreatitis in the dog, but a firm association has not been confirmed in either species. Indeed, anti-inflammatory doses of glucocorticoids appear to be beneficial in the management of experimental canine acute pancreatic necrosis.50 NUTRITION - High fat feedings51 and obesity49 have been associated with the development of pancreatitis in the dog, but similar associations have not been made in the cat. Most recent surveys have associated underweight body condition with the development of feline ANP.2,6,8,10

PATHOGENESIS

The acinar and ductal cells of the exocrine pancreas are interspersed between the islet cells of the endocrine pancreas. Like the endocrine pancreas, the exocrine pancreas is a secretory organ with several physiologic functions. Exocrine pancreatic fluid contains: digestive zymogens which initiate protein, carbohydrate, and lipid digestion; bicarbonate and water which serve to neutralize the duodenum; intrinsic factor which facilitates cobalamin (vitamin B12) absorption in the distal ileum; and, anti-bacterial proteins which regulate the small intestinal bacterial flora. Digestive zymogens are secreted primarily by acinar cells, while bicarbonate, water, intrinsic factor, and anti-bacterial proteins are secreted primarily by ductal cells. The two most common disorders of the exocrine pancreas, acute pancreatic necrosis and exocrine pancreatic insufficiency, are

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readily understood on the basis of these physiologic functions. With acute pancreatic necrosis, premature activation of digestive zymogen within pancreatic acinar cells leads to acinar cell necrosis (trypsin, chymotrypsin, carboxypeptidase), hemorrhage (elastase digestion of blood vessel elastin fibers), and fat necrosis and saponification (lipase digestion of pancreatic, peripancreatic and mesenteric fat). With exocrine pancreatic insufficiency, affected animals develop severe nutrient maldigestion, acid injury to the duodenal mucosa, cobalamin and fat soluble vitamin malabsorption, and bacterial proliferation in the gut (summarized in reference 52). Pancreatic acinar cells protect themselves from intra-acinar activation of zymogen and acinar cell necrosis through several mechanisms: (1) Potentially harmful digestive enzymes are synthesized in the form of inactive precursors or zymogens in the rough endoplasmic reticulum. (2) Zymogens are then transported to the Golgi complex where they undergo selective glycosylations. Lysosomal hydrolases that are eventually packaged in lysosomes are separated from zymogens bound for export as they pass through the Golgi complex. Lysosomal hydrolases are first phosphorylated at the 6 position of mannose residues, bound to receptors specific for 6-phosphoryl mannose, and then transported to lysosomes where the acid pH favors their dissociation from the receptors. Digestive enzymes lack the 6-phosphoryl mannose label, and are instead transported vectorially into a different secretory fraction. (3) Packaging of zymogens into maturing zymogen granules sequesters them from contact with other sub-cellular fractions. (4) Pancreatic secretory trypsin inhibitor (PSTI) is incorporated into the maturing zymogen granules. PSTI inactivates trypsin should there be any intra-acinar activation of trypsinogen. (5) Following stimulation (e.g., feeding and cholecystokinin secretion), mature zymogen granules and their contents are released from the cell into the ductal lumen in a process of membrane fusion and exocytosis. (6) Finally, zymogens are activated physiologically only after they enter the duodenum, where the brush border enzyme 52 enteropeptidase activates trypsinogen, and trypsin then activates other pancreatic zymogen. A large body of experimental, and some clinical, evidence suggests that the initiating event of acute pancreatitis is the premature activation of digestive zymogens within the acinar cell.34,53-56 Premature activation of digestive zymogen results in acinar cell necrosis and pancreatic autodigestion. In acute pancreatic necrosis, protein synthesis and intracellular transport to the Golgi complex appear to be normal, but digestive zymogens then become co-localized along with lysosomal hydrolases in large vacuoles. Cell biology studies have revealed that lysosomal and zymogen granule fractions become colocalized through a process known as crinophagy, a process used by many cells to degrade accumulated secretory products when the need for secretion is no longer present. Although this process takes place in other cells without adverse consequences, it can be lethal in pancreatic acinar cells because of the peculiarity of their secretion products (digestive zymogens). Lysosomal hydrolases, such as cathepsin B and N-acetyl glucosaminidase, activate trypsinogen to the active trypsin form, and the enhanced fragility of these large vacuoles permits release of active enzyme into the cell cytoplasm. Trypsin acts auto-catalytically to activate other trypsinogen molecules and other zymogens, each inducing a unique chemical pathology in pancreatic and extra-pancreatic cells. A variety of inflammatory mediators and cytokines, interleukins, nitric oxide, and free radicals are involved in the further evolution of pancreatic acinar cell necrosis and 52,57-60 Thus, a bout of pancreatitis begins with an initiating event, e.g., inflammation and often determine the outcome. ischemia, inflammation, or ductal obstruction, followed by acinar events, i.e., co-localization, enzyme activation, and cell injury, the outcome of which is influenced by severity determinants, e.g., inflammatory cytokines, reactive oxygen species, altered redox state, and apoptosis.59 The further evolution of acute pancreatic necrosis to a systemic inflammatory response syndrome (SIRS) and multiple organ dysfunction syndrome (MODS) is determined by the balance of proinflammatory and anti-inflammatory cytokines.60

CLINICAL SIGNS

HISTORY Siamese cats were initially reported to be at increased risk for the disease in one of the first retrospective studies of feline pancreatitis.2 Clinical case surveys of the past 10 years suggest that most cases of feline pancreatitis are seen in the Domestic Short Hair breed.1-10 Anorexia (87%) and lethargy (81%) are the most frequently reported clinical signs in cats with acute pancreatitis, but these clinical signs are not pathognomonic for pancreatitis. Anorexia and lethargy are the most important clinical signs in many feline diseases. Gastroenterologic signs are sporadic and less frequently reported in the cat. Vomiting and diarrhea are reported in only 46% and 12% of cases, respectively,2-7,9,10 In dogs, vomiting (90%) and diarrhea (33%) appear to be more important clinical signs.12,27,49 PHYSICAL EXAMINATION FINDINGS

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Physical examination findings in cats with acute necrotizing pancreatitis include dehydration (54%), hypothermia (46%), icterus (37%), fever (25%), abdominal pain (19%), and abdominal mass (11%).2-7,9,10 These findings suggest that a "classic textbook" description of acute pancreatitis (e.g. vomiting, diarrhea, abdominal pain, and fever) is not consistently seen in the domestic cat. Many of these physical examination findings are more commonly reported in canine acute pancreatitis. Abdominal pain (58% in dogs; 19% in cats) and fever (32% in dogs; 25% in cats), for example, are more commonly reported in dogs with acute pancreatitis.12,27,49

DIFFERENTIAL DIAGNOSIS

The major differential diagnoses for feline acute necrotizing pancreatitis include gastrointestinal foreign body, inflammatory bowel disease, infectious gastroenteritis, gastrointestinal intussusception and neoplasia, cholangitis, biliary tract neoplasia, and various forms of liver pathology.

DIAGNOSIS

As with the same condition in the dog, diagnosis of acute necrotizing pancreatitis requires the careful integration of historical, physical examination, clinicopathologic, and imaging findings. Where appropriate, additional diagnostic support may be obtained at the time of laparoscopy or exploratory laparotomy. Diagnosis should not be made on the basis of a single laboratory or imaging finding. LABORATORY FINDINGS In cats affected with acute necrotizing pancreatitis, laboratory abnormalities have included: normocytic, normochromic, regenerative or non-regenerative anemia (38%), leukocytosis (46%), leukopenia (15%), hyperbilirubinemia (58%), hypercholesterolemia (72%), hyperglycemia (45%), hypocalcemia (65%), hypoalbuminemia (36%), and elevations in serum 2-7,9,10 Changes in red blood cell counts, serum alanine aminotransferase (57%) and alkaline phosphatase (49%) activities. activities of liver enzymes, and serum concentrations of bilirubin, glucose, and cholesterol are fairly consistent findings in feline acute necrotizing pancreatitis, just as they are in dogs.12,27,49 Important differences between cats and dogs appear to be reflected in white blood cell counts and serum calcium concentrations. Leukocytosis is a more important clinical finding in the dog (62% in dogs; 46% in cats).12,27,49 Leukopenia is sometimes seen instead of leukocytosis in cats, and a worse prognosis has been attributed to leukopenia in the cat.2,5,7,10 Hypocalcemia also appears to be a more frequent finding in cats (3-5 % in dogs12,49; 45-65% in cats2,5,6,10). Hypocalcemia (total and serum ionized) may result from several mechanisms, including acid-base disturbances, peripancreatic fat saponification, and parathormone resistance.61 Regardless of the mechanism, hypocalcemia appears to confer a worse clinical prognosis in cats.6,10 This finding suggests that cats should be monitored fairly closely for the development of hypocalcemia and treatment should be initiated, accordingly. SPECIAL TESTS OF PANCREATIC FUNCTION Lipase and Amylase Activity Assays ­ Serum lipase activities are elevated in experimental feline pancreatitis,62,63 but serum lipase and amylase activities do not appear to be elevated or of clinical value in the diagnosis of clinical pancreatitis.a Serum lipase activity may still have some clinical utility in the diagnosis of acute necrotizing pancreatitis in the dog.12,64 Assays of serum lipase activity are complicated by the fact that there may be as many as five different isoenzymes circulating in the blood,65 consequently general serum lipase activity assays have been superseded by the development of pancreatic lipase immunoreactivity assays (e.g., cPLI, fPLI).65,66 Trypsin-like Immunoreactivity (TLI) ­ Serum TLI mainly measures trypsinogen but also detects trypsin and some trypsin molecules bound to proteinase inhibitors.66 TLI assays are species-specific, and different assays for feline (fTLI) and canine (cTLI) have been developed and validated.67 Serum TLI concentration is the diagnostic test of choice for feline exocrine pancreatic insufficiency because it is highly sensitive and specific for this disease in the cat.11 The use of this test in the diagnosis of feline acute necrotizing pancreatitis is less clear. Serum trypsinogen-like immunoreactivity (TLI) concentrations are transiently elevated in experimental feline acute pancreatitis,b but elevations in clinical cases are less consistently seen.a,5,7 The poor sensitivity (i.e., 33%) of this test precludes its use as a definitive assay for feline acute necrotizing pancreatitis. Trypsinogen Activation Peptide (TAP) ­ When trypsinogen is activated to trypsin, a small peptide, TAP, is split from the trypsinogen molecule. Under normal conditions, activation of trypsinogen takes place only in the small intestine and TAP is undetectable in the blood. During pancreatitis, trypsinogen is activated prematurely in pancreatic acinar cells and TAP is released into the vascular space.66 Urine TAP assays have shown some promise in experimental models of feline

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pancreatitis,68 whereas serum TAP assays have shown some utility in preliminary clinical studies.c Large clinical trials will be required to determine the true specificity and sensitivity of this assay. Pancreatic Lipase Immunoreactivity (PLI) ­ A radioimmunoassay for the measurement of pancreatic lipase immunoreactivity (fPLI) has been developed and validated in the cat.69 fPLI elevations have been cited in preliminary reports of experimentalb and clinicald feline acute necrotizing pancreatitis. Multi-institutional prospective clinical studies will be required to determine the true sensitivity and specificity of fPLI in the diagnosis of feline ANP. IMAGING FINDINGS Radiography - The radiographic findings of feline acute necrotizing pancreatitis have not been very well characterized. The radiographic hallmarks of canine acute pancreatitis (e.g. increased density in the right cranial abdominal quadrant, left gastric displacement, right duodenal displacement, and gas-filled duodenum/colon)12,70 have not been substantiated in the cat. Indeed, in several recent reports, many of these radiographic findings were not reported in cats with documented acute pancreatic necrosis.1-10 In spontaneous clinical cases, hepatomegaly and abdominal effusion appear to be the only radiographic findings associated with feline APN.1-10 Ultrasonography - Enlarged, irregular, and/or hypoechoic pancreas, hyperechogenicity of the peripancreatic mesentery, and peritoneal effusion have been observed with abdominal ultrasonography in many cats with spontaneous acute pancreatitis.3-8,10 The specificity of this imaging modality appears to be high (>85%), but the sensitivity has been reported as low as 35% in some studies.5,7,8 The low sensitivity suggests that imaging the pancreas in cats with pancreatitis is technically more difficult than imaging the pancreas in dogs or that the ultrasonographic appearance of pancreatitis in cats differs from that reported for dogs. New diagnostic criteria may be needed if abdominal ultrasonography is to be a more effective tool in the diagnosis of pancreatitis in cats.8,71 Computed Tomography - CT scanning appears to be useful in identifying the normal structures of the healthy feline pancreas,72 but preliminary clinical reports have been somewhat disappointing.d,7 The sensitivity of CT scanning in detecting lesions consistent with feline acute necrotizing pancreatitis may be as low as 20%.d,7 Additional study will be needed to determine the specificity and sensitivity of this imaging modality in the diagnosis of feline acute necrotizing pancreatitis. BIOPSY If clinically indicated, pancreatic biopsy may be obtained by laparoscopy or exploratory laparotomy. Clinicians should always bear in mind that many pancreatitis patients are poor anesthetic risks. Gross observation at the time of laparoscopy or exploratory laparotomy may confirm the diagnosis of acute necrotizing pancreatitis. In equivocal cases, biopsy may be safely performed as long as blood flow is preserved at the site of the biopsy. Single biopsy may be insufficient to exclude subclinical pancreatitis as inflammation of the canine pancreas has been shown to occur in discrete areas within the 73 Similar findings have been reported in feline acute pancreas rather than diffusely throughout the whole organ. 2 necrotizing pancreatitis. Inspection of other viscera (e.g., intestine, biliary tract, liver) at the time of laparoscopy or exploratory laparotomy is of paramount importance in the cat because of the high rate of disease concurrence in this species.2,3,9,10,14,20,21

SPECIES DIFFERENCES

There are many important species differences between dogs and cats with regard to the clinical course and pathophysiology of acute pancreatic necrosis (summarized in reference 27). Fever, leukocytosis, vomiting, and abdominal pain are important physical examination findings in dogs with acute necrotizing pancreatitis, but these are relatively infrequent findings in cats with ANP. Cats more often have hypothermic reactions, and they may not necessarily manifest the classic gastroenterologic signs (e.g., vomiting, diarrhea, abdominal pain) reported in dogs. The imaging findings in cats are also less subtle than what has been reported in dogs; the classic radiographic hallmarks of canine ANP have not reported in the cat. Cats have a greater incidence and severity of hypocalcemia following bouts of acute pancreatic necrosis. Serum total and/or ionized hypocalcemia is significantly reduced in 45-65% of affected cats, whereas hypocalcemia is reported in only 5% of affected dogs. The pathogenesis of hypocalcemia in cats with ANP is incompletely 6 understood, but it does carry a significantly worse prognosis for recovery. Prior gastrointestinal tract disease confers slight increased risk for the development of acute pancreatic necrosis in the dog;12,49 this is especially true of the cat.2,10,14,20,21

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THERAPY

Supportive care continues to be the mainstay of therapy for feline acute pancreatitis. Efforts should be made to identify and eliminate any inciting agents, sustain blood and plasma volume, correct acid/base, electrolyte, and fluid deficits, place the pancreas in physiologic rest (NPO) for short periods of time, and treat any complications that might develop. Important life-threatening complications of acute pancreatitis in cats include hypocalcemia, disseminated intravascular coagulation, thromboembolism, cardiac arrhythmia, sepsis, acute tubular necrosis, pulmonary edema and pleural effusion. Historically, a short period of fasting of food and water has been recommended for cats with acute necrotizing pancreatitis. This recommendation should be applied only in those cats in which there is severe vomiting and risk for aspiration pneumonia. As obligate carnivores, cats develop fat mobilization and hepatic lipidosis during prolonged starvation. Moreover, recent studies suggest that it may be appropriate and necessary to stimulate pancreatic secretion (via feeding) in 53-56 Esophagostomy, gastrostomy, and enterostomy tubes may be placed to facilitate nutrition in affected animals. anorectic animals. Other therapies that may be of some benefit in the treatment of this disorder include: RELIEF OF PAIN - Analgesic agents should be used when abdominal pain is suspected. Most cats do not manifest clinical signs of abdominal pain, but clinicians should be suspicious for it. Meperidine at a dose of 1-2 mg/kg administered intramuscularly or subcutaneously every 2-4 hours or butorphanol at a dose of 0.2-0.4 mg/kg administered subcutaneously every 6 hours have been recommended.74 ANTI-EMETIC AGENTS - Nausea and vomiting may be severe in affected animals. The 2 adrenergic antagonists and 5-HT3 antagonists appear to be the most effective anti-emetic agents in the cat.75 Cats may be treated with chlorpromazine (2 adrenergic antagonist) at a dose of 0.2-0.4 mg/kg administered subcutaneously or intramuscularly every 8 hours, or with any of the 5-HT3 antagonists (ondansetron 0.1-1.0 mg/kg, granisetron 0.1-0.5 mg/kg, or dolasetron 0.5-1.0 mg/kg, orally or intravenously every 12-24 hours). Dopaminergic antagonists, e.g., metoclopramide, are less effective anti-emetic agents in the cat.75 CALCIUM GLUCONATE SUPPLEMENTATION - Hypocalcemia is a frequent complication of feline acute necrotizing pancreatitis and is associated with a worse prognosis.6 Calcium gluconate should be given at doses of 50-150 mg/kg intravenously over 12-24 hours and serum total or ionized calcium concentrations should be monitored during therapy. H1 AND H2 HISTAMINE ANTAGONISTS - Histamine and bradykinin-induced increases in microvascular permeability are associated with the development of hemorrhagic necrosis in experimental feline pancreatitis.76 Treatment with H1 (mepyramine, 10 mg/kg) and H2 (cimetidine, 5.0 mg/kg) histamine receptor antagonists protects against the development of hemorrhagic pancreatitis in these models.76 Efficacy has not been established in clinical pancreatitis, but the use of these drugs in suspected or proven clinical cases would seem to make sense since they are associated with few side effects. Diphenydramine (2-4 mg/kg) or dimenhydrinate (4-8 mg/kg) are examples of clinically used H1 histamine receptor antagonsists. Cimetidine (5.0 mg/kg), ranitidine (1.0-2.0 mg/kg), famotidine (0.5-1.0 mg/kg), and nizatidine (2.5-5.0 mg/kg) are examples of clinically used H2 histamine receptor antagonists. LOW DOSE DOPAMINE INFUSION - Low dose dopamine infusion (5 g/kg/min) improves pancreatic blood flow and reduces microvascular permeability in feline experimental pancreatitis.63 Low dose dopamine infusion is effective treatment in experimental pancreatitis even when it is given up to 12 hours after induction of the disease.63 Part of the appeal of dopamine as a potential treatment for feline pancreatitis lies in the diversity of its actions. Dopamine's effect on the kidney in promoting renal blood flow and urinary output, and its cardiac inotropic effect make it an ideal agent, although it has not yet been studied in controlled clinical trials. BROAD SPECTRUM ANTIBIOTICS - Acute necrotizing pancreatitis may begin as a sterile process, but necrosis and inflammation predispose to colonic bacterial translocation and colonization of the pancreas.77,78 E. coli and other coliforms are the principal pathogens.77,78 High colonization rates suggest that bacteria may spread to the inflamed pancreas more frequently than is currently thought, and that broad spectrum antibiotics may be appropriate in suspected cases of feline acute pancreatitis. Cefotaxime at a dose of 50 mg/kg administered intramuscularly every eight hours prevents bacterial colonization of the pancreas.79 DUCTAL DECOMPRESSION - Surgical decompression of the pancreaticobiliary duct should be considered in cases of acute ductal obstruction, e.g., calculus, neoplasia, and fluke infection. Ductal decompression may also be useful in acute cases that have progressed to the more chronic form of the disease. Ductal decompression has been shown to restore pancreatic blood flow, tissue pH, and acinar cell function.31,32

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PREVENTION

In cases in which inflammatory bowel disease is the underlying pathogenesis of acute necrotizing pancreatitis, therapy should be directed toward regulation of the IBD. The five components of feline IBD therapy are dietary modification, antibiotics, probiotics, anti-diarrheal agents, and immunosuppressive therapy.80

COMPLICATIONS OF ACUTE NECROTIZING PANCREATITIS ­ CHRONIC NON-SUPPURATIVE PANCREATITIS

Recurring bouts of acute necrotizing pancreatitis may progress to a chronic non-suppurative form of the disease. This chronic form of pancreatitis has generally been held to be of lesser clinical severity, lower mortality, and better long term prognosis.1 More recent reports suggest however that chronic pancreatitis cannot be differentiated from acute pancreatitis by clinical, clinicopathologic, or imaging findings.10 The clinical signs, laboratory data, and imaging findings are indistinguishable between the two groups. Histopathology remains the only dependable method of differentiating acute and chronic pancreatitis. Not surprisingly, cats with chronic pancreatitis more frequently have concurrent systemic disease (e.g., cholangitis, IBD) compared to cats with acute pancreatitis.10

COMPLICATIONS OF ACUTE NECROTIZING PANCREATITIS ­ EXOCRONE PANCREATIC INSUFFICIENCY (EPI)

Exocrine pancreatic insufficiency (EPI) is an uncommon cause of chronic diarrhea in cats. Insufficiency results from failure of synthesis and secretion of pancreatic digestive enzymes. The natural history of feline exocrine pancreatic insufficiency is poorly understood, but most cases are believed to result from chronic pancreatitis, fibrosis, and acinar atrophy. As with dogs, clinical signs reported in cats with EPI include weight loss, soft voluminous feces, and ravenous appetite. Affected cats may have an antecedent history of recurring bouts of acute pancreatitis (e.g., anorexia, lethargy, vomiting) culminating in chronic pancreatitis and EPI. The diagnosis of EPI in cats has been technically difficult. Clinical signs in affected cats are not pathognomonic for EPI, clinicopathologic data are fairly non-specific, imaging findings are inconsistent, and the severity of pancreatic histologic changes are not always directly related to the severity of clinical signs. One study suggests that serum TLI may be useful in 11 the diagnosis of this disease. In that study, TLI concentrations less than 8 g/L (reference range = 17-49 g/L) were reported in 17/20 cats with clinical signs compatible with EPI (e.g., weight loss, loose voluminous feces, greasy soiling of the hair coat) and at least one other finding, e.g., decreased fecal proteolytic activity, exploratory laparotomy or necropsy findings compatible with EPI, or favorable response to pancreatic enzyme replacement therapy. Cats affected with EPI have predictable serum cobalamin deficiency because of pancreatic intrinsic factor deficiency and cobalamin malabsorption.81 Therapy should include subcutaneous vitamin B12 injections (100 µg subcutaneously every 3-4 weeks) in addition to pancreatic replacement enzymes.

COMPLICATIONS OF ACUTE NECROTIZING PANCREATITIS ­ HEPATIC LIPIDOSIS

Acute necrotizing pancreatitis is but one of many examples in which anorexia or starvation predisposes an obligate carnivore to the syndrome of fat mobilization and hepatic lipidosis.1,3,82 The concurrence of these two syndromes is a particularly poor prognostic sign in that affected cats have high morbidity and mortality rates. This emphasizes the importance of early interventions in the treatment of pancreatitis before the development of the metabolic syndrome of hepatic lipidosis.

Several studies have related severe chronic pancreatitis to the development of diabetes mellitus.1,4,10,11 Acute necrotizing pancreatitis per se may not necessarily be a risk factor for the development of diabetes mellitus, but disease progression to the chronic non-suppurative form may increase that risk.

COMPLICATIONS OF ACUTE NECROTIZING PANCREATITIS ­ DIABETES MELLITUS

FOOTNOTES

Parent C, Washabau RJ, Williams DA, et al. Serum trypsin-like immunoreactivity, amylase and lipase in the diagnosis of feline acute pancreatitis. Journal of Veterinary Internal Medicine 1995; 9: 194. b Williams DA, Steiner JM, Ruaux CG, Zavros N. Increases in serum pancreatic lipase immunoreactivity (PLI) are greater and of longer duration than those of trypsin-like immunoreactivity (TLI) in cats with experimental pancreatitis. Journal of Veterinary Internal Medicine 2003; 17: 445. c Allen H, Broussard J, Steiner JM, Mansfield CS, Williams DA. Comparison of clinical utility of different serum and urinary markers for feline pancreatitis. Journal of Veterinary Internal Medicine 2003; 17: 411.

a

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d

Forman MA, Marks SL, DeCock HE, Hergesell ES, Wisner ER, Bakter T, Steiner JM, Williams DA. Evaluation of feline pancreatic lipase immunoreactivity and helical computed tomography versus conventional testing for the diagnosis of feline pancreatitis. Journal of Veterinary Internal Medicine 2003; 17: 411.

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24. Johnston KL, Swift NC, Forster-van Hijfte M, Batt RM. Comparison of bacterial flora of the duodenum in healthy cats and cats with signs of gastrointestinal disease. Journal of the American Veterinary Medical Association 2001; 218:48-51. 25. de Vos WC. Migrating spike complex in the small intestine of the fasting cat. American Journal of Physiology 1993; 265: G619-G627. 26. Sparkes AH et al. Effect of dietary supplementation with fructooligosaccharides on fecal flora of healthy cats. American Journal of Veterinary Research 1998; 59: 436-439. 27. Washabau RJ. Feline acute pancreatitis ­ important species differences. Journal of Feline Medicine and Surgery 2001; 3: 95-98. 28. Reber HA, Karanjia ND, Alvarez C, Widdison AL, Leung FW, Ashley SW, Lutrin FJ. Pancreatic blood flow in cats with chronic pancreatitis. Gastroenterology 1992; 103: 652-659. 29. Karanjia ND, Singh SM, Widdison AL, Lutrin FJ, Reber HA. Pancreatic ductal and interstitial pressures in cats with chronic pancreatitis. 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Pancreatic duct obstruction in rabbits causes digestive zymogen and lysosomal enzyme colocalization. Journal of Clinical Investigation 1989; 84: 1260-1266. 35. Dubey JP, Carpenter JL. Histologically confirmed clinical toxoplasmosis in cats: 100 cases. Journal of the American Veterinary Medical Association 1993; 203: 1556-1566. 36. Sherding RG. Feline infectious peritonitis. Compendium of Continuing Education for the Practicing Veterinarian. 1979; 1: 95-101. 37. VonSanderslebe J, Popischil A, Kraft W. Infection of the pancreas with parvovirus in young kittens. DTW Dtsch Tieraztl Wochenschr 1983; 90: 297-340. 38. Rothenbacher H, Lindquist WD. Liver cirrhosis and pancreatitis in a cat infected with Amphimerus pseudofelineus. Journal of the American Veterinary Medical Association 1963; 143: 1099-1102. 39. Hurley KE, Pesavento PA, Pedersen NC, Poland AM, Wilson E, and Foley JE. An outbreak of virulent systemic feline calicivirus disease. Journal of the American Veterinary Medical Association 2004; 224(2): 241-249. 40. Schorr-Evans EM, Poland A, Johnson WE, et al. An epizootic of highly virulent feline calicivirus disease in a hospital setting in New England. Journal of Feline Medicine & Surgery 2003; 5(4): 217-226. 41. Pedersen NC, Elliott JB, Glasgow A, Poland A, and Keel K. An isolated epizootic of hemorrhagic-like fever in cats caused by a novel and highly virulent strain of feline calicivirus. Veterinary Microbiology 2000; 73(4):281-300. 42. Suter PF, Olsson SE. Traumatic hemorrhagic pancreatitis in the cat: a report with emphasis on the radiological diagnosis. Journal of the American Veterinary Radiology Society 1969; 10: 4-11. 43. Westermarck E, Saario E. Traumatic pancreatic injury in a cat ­ case history. Acta Veterinaria Scandinavica 1989; 30: 359-362. 44. Liu S, Oghuchi Y, Borner JW, Runge W, Dressel TD, Goodale RL. Increased canine pancreatic acinar cell damage after organophosphate and acetylcholine or cholecystokinin. Pancreas 1990; 2: 177-182. 45. Ryan CP, Howard EB. Systemic lipodystrophy associated with pancreatitis in a cat. Feline Practice 1981; 11: 31-34. 46. Layer P, Hotz J, Eysselein VE, Jansen JBMJ, Lamers CBHW, Schmitz-Moormann HP, Goebell H. Effects of acute hypercalcemia on exocrine pancreatic secretion in the cat. Gastroenterology 1985; 88: 1168-1174. 47. Frick TW, Hailemariam S, Heitz PU, Largiader F, Goodale RL. Acute hypercalcemia induces acinar cell necrosis and intraductal protein precipitates in the pancreas of cats and guinea pigs. Gastroenterology 1990; 98: 1675-1681. 48. Layer P, Hotz J, Schmitz-Moormann HP, Goebell H. Effects of experimental chronic hypercalcemia in feline exocrine pancreatic secretion. Gastroenterology 1982; 82: 309-316. 49. Hess RS, Kass PH, Shofer FS, Van Winkle TJ, Washabau RJ. Evaluation of risk factors for fatal acute pancreatitis in dogs. Journal of the American Veterinary Medical Association 1999; 214: 46-51. 50. Kiviniemi H, Stahlberg MI, Jalovaara P, Ramo J, Kairaluoma M. Methylprednisolone in acute canine hemorrhagic pancreatitis. Acta Chirurgica Scandinavica 1988; 154: 31-35.

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51. Lindsay S, Entenman C, Chaikoff IL. Pancreatitis accompanying hepatic disease in dogs fed a high fat, low protein diet. Archives of Pathology 1948; 45(5): 635-638. 52. Washabau RJ, Holt DE. Pathophysiology of gastrointestinal disease. In, Textbook of Veterinary Surgery, Slatter D, ed. 3rd edition. WB Saunders, Philadelphia, 2003, pp 530-552 53. Hofbauer B, Saluja AK, Lerch MM, et al. Intra-acinar activation of trypsinogen during cerulein-induced pancreatitis in rats. American Journal of Physiology 1998; 275: G352-G362. 54. Koike H, Steer ML, and Meldolesi J. Pancreatic effects of ethionine: blockade of exocytosis and appearance of crinophagy and autophagy precede cellular necrosis. American Journal of Physiology 242: G297-G307, 1982. 55. Saluja A, Saito I, Saluja M, et al. In vivo rat pancreatic acinar cell function during supramaximal stimulation with cerulein. American Journal of Physiology 1985; 249: G702-G210. 56. Simpson KW, Beechey-Newman N, Lamb CR, et al. Cholecystokinin-8-induces edematous pancreatitis in dogs associated with short burst of trypsinogen activation. Digestive Diseases and Sciences 1995; 40: 2152-2161. 57. Glazer G, Bennett A. Prostaglandin release in canine acute hemorrhagic pancreatitis. Gut 1976; 17: 22-26. 58. Westermarck E, Rimaila-Parnanen E. Serum phospholipase A2 in canine acute pancreatitis. Acta Veterinaria Scandinavica 1983; 24: 477-487. 59. Steer ML. The early intra-acinar cell events which occur during acute pancreatitis. Pancreas 1998; 17: 31-37. 60. Bhatia M, Brady M, Shokuhi S, Christmas S, Neoptolemos JP, and Slavin J. Inflammatory mediators in acute pancreatitis. Journal of Pathology 2000; 190: 117-125. 61. Bhattacharya SK, Luther RW, Pate JW. Soft tissue calcium and magnesium content in acute pancreatitis in the dog: calcium accumulation, a mechanism for hypocalcemia in acute pancreatitis. Journal of Laboratory Clinical Research 1985; 105: 422-427. 62. Kitchell BE, Strombeck DR, Cullen J, Harrold D. Clinical and pathologic changes in experimentally induced acute pancreatitis in cats. American Journal of Veterinary Research 1986; 47: 1170-1173. 63. Karanjia ND, Lutrin FJ, Chang Y-B, et al. Low dose dopamine protects against hemorrhagic pancreatitis in cats. Journal of Surgical Research 1990; 48: 440-443. 64. Strombeck DR, Farver T, Kaneko JJ. Serum amylase and lipase activities in the diagnosis of pancreatitis in dogs. American Journal of Veterinary Research 1981; 42: 1966-1970. 65. Steiner JM, Williams DA. Development and validation of a radioimmunoassay (RIA) for the measurement of canine pancreatic lipase immunoreactivity (cPLI) in serum. American Journal of Veterinary Research 2003; 64(10): 1237-1241. 66. Steiner JM. Diagnosis of pancreatitis. Veterinary Clinics of North America 2003; 33: 1181-1195. 67. Steiner JM, Williams DA, Moeller EM, Melgarejo TL. Development and validation of an enzyme-linked immunosorbent assay (ELISA) for feline trypsin-like immunreactity (fTLI). American Journal of Veterinary Research 2000; 61: 620-623. 68. Karanjia ND, Widdison A, Jehanili A, Hermon-Taylor J, Reber HA. Assay of trypsinogen activation in the cat experimental model of acute pancreatitis. Pancreas 1993; 8: 189-195. 69. Steiner JM, Wilson BG, Williams DA. Purification and partial characterization of feline classical pancreatic lipase. Comparative Biochemistry and Physiology, Part B, Biochemistry & Molecular Biology 2003; 134: 151-159. 70.Kleine LJ, Hornbuckle WE. Acute pancreatitis: the radiographic findings in 82 dogs. Journal of the American Veterinary Radiology Society 1978; 19: 102-106. 71. Etue SM, Penninck DG, Labato MA, Pearson S, Tidwell A. Ultrasonography of the normal feline pancreas and associated anatomic landmarks: a prospective study of 20 cats. Veterinary Radiology & Ultrasound 2001; 42: 330-336. 72. Head LL, Daniel GB, Tobias K, Morandi F, DeNovo R, Donnell R. Evaluation of the feline pancreas using computed tomography and radiolabeled leukocytes. Veterinary Radiology & Ultrasound 2003; 44(4): 420-428. 73. Newman S, Steiner J, Woosley K, Barton L, Ruaux C, and Williams DA. Localization of pancreatic inflammation and necrosis in dogs. Journal of Veterinary Internal Medicine 2004; 18: 488-493. 74. Steiner JM, Williams DA. Feline exocrine pancreatic disorders. Veterinary Clinics of North America 1999; 29(2): 551575. 75. Washabau RJ. Update on anti-emetic therapy. In, Consultations in Feline Internal Medicine IV, ed. August JR. WB Saunders Co, Philadelphia, PA, 2001, pp 107-112. 76. Harvey MH, Wedgwood KR, Reber HA. Vasoactive drugs, microvascular permeability, and hemorrhagic pancreatitis in cats. Gastroenterology 1987; 93: 1296-1300. 77. Widdison AL, Alvarez C, Chang Y-B, Karanjia ND, Reber HA. Sources of pancreatic pathogens in acute pancreatitis in cats. Pancreas 1994; 4: 536-541. 78. Widdison AL, Karanjia ND, Reber HA. Routes of spread of pathogens into the pancreas in a feline model of acute pancreatitis. Gut 1994; 35: 1306-1310.

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79. Widdison AL, Karanjia ND, Reber HA. Antimicrobial treatment of pancreatic infection in cats. British Journal of Surgery 1994; 81: 886-889. 80. Washabau RJ. Diseases of the colon. In, Textbook of Veterinary Internal Medicine, 6th edition, ed. Ettinger SJ, Feldman EC. WB Saunders Co, Philadelphia, PA, 2005, in press. 81. Simpson KW, Fyfe J, Cornetta A, et al. Subnormal concentrations of serum cobalamin (vitamin B12) in cats with gastrointestinal disease. Journal of Veterinary Internal Medicine 2001; 15: 26-32. 82. Center SA, Crawford MA, and Guida L. A retrospective study of 77 cats with severe hepatic lipidosis. Journal of Veterinary Internal Medicine 1993; 7: 349-359.

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COMPANION ANIMAL: Gastrointestinal Issues

FELINE HEPATOBILIARY DISEASE: WHAT'S NEW IN DIAGNOSIS AND THERAPY

Robert J. Washabau, VMD, PhD, DACVIM

Professor of Medicine and Department Chair, Department of Veterinary Clinical Sciences College of Veterinary Medicine, University of Minnesota St. Paul, MN

TOXIC HEPATOPATHY

PATHOGENESIS AND ETIOLOGY - Toxic hepatopathy is a direct injury to hepatocytes or other cells in the liver attributable to therapeutic agents or environmental toxins. Cats are particularly sensitive to phenolic toxicity because of limited hepatic glucuronide transferase activity. The discriminatory eating habits of cats may account for the relatively uncommon occurrence of hepatotoxicity from ingested environmental toxins such as pesticides, household products, and other chemicals. Medical therapies (acetaminophen, acetylsalicylic acid, megesterol, ketoconazole, phenazopyridine, tetracycline, diazepam, griseofulvin) and environmental toxins (pine oil + isopropanol, inorganic arsenicals, thallium, zinc phosphide, white phosphorus, Amanita phalloides, aflatoxin, phenols) may contribute to liver pathology. A severe idiosyncratic hepatotoxicity has been reported with diazepam administration in several groups of cats. Clinical signs in affected cats include anorexia, vomiting, weight loss, ascites, encephalopathy, and death. The histology is characterized by severe central lobular necrosis and mild vacuolation. MECHANISMS OF HEPATOTOXICITY - The liver is an important site of drug toxicity and oxidative stress because of its proximity and relationship to the gastrointestinal tract. Seventy-five to 80% of hepatic blood flow comes directly from the gastrointestinal tract and spleen via the main portal vein. Portal blood flow transports nutrients, bacteria and bacterial antigens, drugs, and xenobiotic agents absorbed from the gut to the liver in more concentrated form. Drug-metabolizing enzymes detoxify many xenobiotics but activate the toxicity of others. Hepatic parenchymal and non-parenchymal cells may all contribute to the pathogenesis of hepatic toxicity. The major mechanisms of hepatotoxicity include: Bile Acid-Induced Hepatocyte Apoptosis, Cytochrome P4502E1-Dependent Toxicity , Peroxynitrite-induced Hepatocyte Toxicity, Adhesion Molecules and Oxidant Stress in Inflammatory Liver Injury, Microvesicular and Nonalcoholic Steatosis. DIAGNOSIS OF HEPATOTOXICITY - Clinical evidence includes supportive history, normal liver size to mild generalized hepatomegaly, elevated serum liver enzyme activities (predominantly ALT and AST), hypoalbuminemia and hypocholesterolemia, and recovery or death depending upon severity and magnitude of exposure. There are no pathognomonic histologic changes in the liver, although necrosis with minimal inflammation and lipid accumulation are considered classic findings. TREATMENT OF HEPATOTOXICITY - Few hepatotoxins have specific antidotes, and recovery relies almost exclusively on symptomatic and supportive therapy. If recognized, acetaminophen toxicity may be treated with acetylcysteine (sulfhydryl group donor), ranitidine or cimetidine (cytochrome P450 enzyme inhibition), ascorbic acid (anti-oxidant), and androstanol (consititutive androstane receptor [CAR] inhibition).

HEPATIC LIPIDOSIS

PATHOGENESIS AND ETIOLOGY - Feline hepatic lipidosis is now a well-recognized syndrome characterized by intracellular accumulation of lipid with clinicopathologic findings consistent with intrahepatic cholestasis. The precise incidence of the syndrome is unknown but pathology surveys have revealed 5% of animals affected with this lesion. While some cases result from diabetes mellitus, the majority of cases are felt to result from the nutritional and biochemical peculiarities of the cat. It has been suggested, for example, that the cat is not very capable of regulating intermediary metabolism during starvation. Although the biochemistry of this lesion has not been completely worked out, there are several biochemical and nutritional peculiarities that predispose the cat to this syndrome. Some of the known biochemical peculiarities of the cat are: essentiality of dietary arginine; low levels of hepatic ornithine; high dietary protein requirements; lack of hepatic enzymatic adaptation to low dietary levels of protein; relative insufficiency of intestinal pyrroline-5-carboxylate synthase

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activity; relative insufficiency of intestinal and hepatic glutamate reductase; relative insufficiency of intestinal ornithine transcarbamylase; peculiarities in lipoprotein metabolism; and, differences in orotic acid metabolism. CLINICAL FEATURES - Most studies suggest that there are no breed, sex, or age predilections. A recent retrospective study by Center and her colleagues suggests that female and middle-age cats are at greater risk for the illness. Obesity may be a predisposing factor, although the syndrome readily develops in fit animals. It has been suggested that obesity followed by a period of anorexia and weight loss are particularly at risk. Cats affected with this syndrome are often presented with a complaint of anorexia, often of several weeks duration. These cats are also commonly presented with jaundice. Other reported clinical signs include vomiting, weakness, weight loss, and diarrhea. Physical examination often reveals dehydration, cachexia, jaundice, and hepatomegaly. All of these findings are also reported in cats with acute pancreatitis and other hepatobiliary disease. DIAGNOSIS - Hyperechoic changes in the hepatic parenchyma at ultraonography have been cited as a pathognomonic finding, but these changes may be seen in other feline hepatic disorders. Diagnosis should be substantiated by aspiration cytology, or better still, tissue biopsy (percutaneous, trans-abdominal ultrasound guidance, laparoscopy, or open laparotomy). Aspiration cytology has weak sensitivity and specificity, and may miss other diagnoses. THERAPY - Nutritional support is the cornerstone of therapy of this disorder. Most studies suggest that enteral feeding (by "forced" or encouraged feeding, pharyngostomy, gastrostomy, or enterostomy feeding tube) of commercially available cat foods will effect recovery in 90-95% of affected animals. Biourge and his colleagues have characterized some of the metabolic changes that take place during fasting in obese cats. They have been particularly interested in the effects of protein, lipid, or carbohydrate supplementation on hepatic lipid accumulation during rapid weight loss in obese cats. They found that small amounts of protein administered to obese cats during fasting significantly reduced accumulation of lipids in the liver, prevented increases in alkaline phosphatase activity, eliminated negative nitrogen balance, and appeared to minimize muscle catabolism. Carbohydrate supplementation reduced hepatic lipid accumulation, but metabolic abnormalities still developed. Lipid supplementation alone did not ameliorate hepatic lipidosis and even resulted in more severe lipid accumulation than under conditions of fasting alone. The use of benzodiazepine agonists (e.g. diazepam, oxazepam, elfazepam) and 5-HT2 agonists (e.g., cyproheptadine) as appetite stimulants has been encouraged in anorexic cats. These compounds particularly the benzodiazepine agonists, should be used with caution as they may exacerbate preexisting hepatic encephalopathy. Benzodiazepine agonists have been shown to worsen hepatoencephalopathy in other animal species through activation of the neuronal benzodiazepine/GABA receptor-chloride channel complex.

FELINE CHOLANGITIS

PATHOGENESIS AND ETIOLOGY - This syndrome has been classified in three different ways: Univeristy of Minnesota Classification (Doug Weisse; 1996) - Lymphocytic portal hepatitis and suppurative cholangitis. This classification system implies that there are two different inflammatory conditions involving the feline liver: inflammatory liver disease (lymphocytic portal hepatitis) and inflammatory biliary tract disease (suppurative cholangitis). Limitations of this classification system ­ It fails to recognize that acute (i.e., suppurative) cholangitis can progress to more chronic forms (i.e., lymphocytic) of the disease. This system also implies that there is suppuration, which, in fact, is rarely seen. Neutrophilic infiltrates do occur, but rarely does it progress to suppuration. Finally, it's not entirely clear whether lymphocytic portal hepatitis is a distinct clinical entity or just a histologic lesion. WSAVA International Liver Standardization Group Classification (Multi-Institutional Group; 2002) - Neutrophilic cholangitis, lymphocytic cholangitis, lymphocytic portal hepatitis. This classification system implies that there are acute (neutrophilic) and chronic (lymphocytic) forms of cholangitis, and that there may be a separate form of portal hepatitis in cats. Limitations of this classification system ­ We still don't know if lymphocytic portal hepatitis is a disease or a histologic lesion. NEUTROPHILIC CHOLANGITIS - This disorder has been seen primarily in young to middle-aged male cats with clinical signs of acute vomiting, diarrhea, anorexia, and lethargy. Physical examination findings often reveal fever, icterus, abdominal pain, and hepatomegaly (<50% of cases). Laboratory findings frequently reveal mild to moderate leukocytosis with mild to moderate elevations in ALT, AST, GGT, and ALP. Based on recent studies, cats affected with this form of cholangitis often have related disease, e.g., pancreatitis and inflammatory bowel disease. The diagnosis of suppurative cholangiohepatitis is

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achieved by serum liver enzymology; ultrasonographic characterization of the liver parenchyma; culture - bile, gallbladder, cholelith, liver; Gram staining; and, biopsy of the liver and/or extrahepatic biliary system. Common bacterial isolates in affected cases include E. coli, Clostridia, Bacteroides, Actinomyces, -Strep. The treatment of this syndrome has included appropriate antibiotic based on culture and sensitivity, cholelith removal where appropriate, bile duct decompression if necessary, fluid and electrolyte maintenance, and ursodeoxycholate therapy (10-15 mg/kg P.O. SID). LYMPHOCYTIC CHOLANGITIS - Chronic lymphocytic cholangitis is characterized by a mixed inflammatory response (equal numbers of lymphocytes or plasma cells and neutrophils) within portal areas and bile ducts. Other features of chronicity include marked bile duct proliferation, bridging fibrosis, and pseudolobule formation. Chronic cholangiohepatitis may progress to progressive biliary cirrhosis and the death of the patient. Lymphocytic cholangitis may represent a persistent bacterial infection or an immune-mediated response may result in a chronic self-perpetuating disorder. Clinical signs are usually of a chronic, intermittent or persistent nature. With chronic cholangiohepatitis, a long-standing history over a period of weeks or months is more likely. Vomiting, icterus, hepatomegaly and ascites are common findings. Hepatic encephalopathy and excessive bleeding are uncommon unless severe end-stage liver disease is present. The best treatments for this syndrome are not clearly understood. It has been suggested that many cats require multi-component therapy, e.g., glucocorticoids - 1-2 mg/kg PO SID; metronidazole - 7.5 mg/kg PO BID; ursodeoxycholate 10-15 mg/kg PO SID; vitamin K1 - 1.5-5 mg Q 2-3 weeks; dietary manipulation for presumed I.B.D.; and, immune modulation with azathioprine or chlorambucil. LYMPHOCYTIC PORTAL HEPATITIS - A retrospective review of liver biopsies of cats with inflammatory liver disease identified a subset of cats with lymphocytic portal infiltrates which had histopathologic features distinct from cats with acute or chronic cholangitis. The term lymphocytic portal hepatitis has been proposed for this disorder. As opposed to findings in cholangitis, there is a lack of neutrophilic inflammation, bile duct involvement, infiltration of inflammatory cells into hepatic parenchyma, or periportal necrosis. Lymphocytic portal hepatitis is not associated with inflammatory bowel disease or pancreatitis. Previous reports of progressive lymphocytic cholangitis or lymphocytic cholangitis referred to varying degrees of neutrophilic inflammation and the condition may actually have been a chronic form of cholangitis. Lymphocytic portal hepatitis is a common finding in liver biopsies of older cats, suggesting that it is a common aging change or that a sub-clinical form of disease is prevalent. Lymphocytic portal hepatitis appears to progress slowly with varying degrees of portal fibrosis and bile duct proliferation but no pseudolobule formation. Concurrent hepatic lipidosis is less likely than with cholangitis.

HEPATIC NEOPLASIA

PATHOGENESIS AND ETIOLOGY - Primary neoplasms of the feline liver are uncommon. Cholangiocellular carcinoma and hepatocellular carcinoma are the most important of the primary feline liver neoplasms, but they are of very low incidence and therefore minor importance. Metatstatic liver neoplasia are much more important in cats. The most common metastatic tumors to the liver are lymphoma, systemic mast cell disease, hemangiosarcoma, and myeloproliferative disorders. CLINICAL FEATURES - Clinical signs are fairly non-specific, but may be similar to clinical signs reported in cats with other liver disorders, for example: lethargy, anorexia, weight loss, and intermittent vomiting. Abdominal effusion, jaundice, and encephalopathy may be seen terminally. DIAGNOSIS - Laboratory data are also usually non-specific. Elevations in serum liver enzyme activities and abnormalities in bile salt metabolism should be obvious, but they are not remarkably different from cats with other liver disorders. Imaging studies (radiography, ultrasonography) may provide evidence of diffuse hepatomegaly or of discrete tumors involving one or more liver lobes. Definitive diagnosis always requires aspiration cytology, or better yet, tissue biopsy. Aspirates and/or tissue biopsies may be obtained by percutaneous trans-abdominal ultrasound guidance, laparoscopy, or laparotomy techniques. THERAPY - The cell of origin of a metastatic tumor should always be identified, if possible. Chemo- or other therapies may then be selected based on a working knowledge of the biologic basis of the tumor. Focal tumors of the liver may be best managed by hepatic lobe resection.

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EXTRA-HEPATIC BILE DUCT OBSTRUCTION

PATHOGENESIS AND ETIOLOGY - Extra-hepatic cholangitis, malignancy, pancreatitis, cholelithasis, and liver flukes (Eurytrema procyonis, Platynosomum concinnum) are the major causes of extra-hepatic biliary obstruction in cats. Progressive cholangitis accounts for over 50% of the cases of hepatic duct obstruction, common bile duct obstruction, and progressive hepatobiliary failure. CLINICAL FEATURES - Affected cats have marked persistent hyperbilirubinemia, and marked elevations in serum ALT, AST, ALP, GGT, and serum bile acids. Ultrasonographic evidence of obstruction is obvious, and many cats undergo exploratory laparotomy and biliary decompression. DIAGNOSIS - As with other feline hepatobiliary disorders, diagnosis of extra-hepatic bile duct obstruction requires careful integration of history, physical examination, laboratory data, and imaging findings. PROGNOSIS AND THERAPY - The prognosis for cats with extra-hepatic biliary obstruction, regardless of underlying pathogenesis is guarded to poor, and perioperative morbidity and mortality is high. The majority of cats have a prolonged disease course, and long-term complications include recurring bouts of cholangitis, weight loss, and biliary tract obstruction.

CONGENITAL PORTOSYSTEMIC SHUNTS

PATHOGENESIS AND ETIOLOGY - Diversion of portal blood flow to the central circulation depletes the liver of nutrients, hormones, and growth factors. Portosystemic shunts in cats are generally extra-hepatic and most arise from the left gastric vein. Portosystemic shunting results in poor hepatocyte growth and function, and the liver undergoes progressive atrophy. CLINICAL FEATURES AND DIAGNOSIS - Affected cats appear stunted, fail to grow, and have excessive salivation perhaps as an early manifestation of hepatoencephalopathy. Cats may manifest other behavioral and neurologic abnormalities such as seizures, dementia, visual disturbances, and ataxia. Onset of clinical signs with feeding and delayed recovery from anesthetic events are reported more frequently with canine portosystemic shunts. Affected cats may have only subtle laboratory abnormalities (mild increases in ALT & AST; mild hypoalbuminemia and hypocholesterolemia; low blood urea nitrogen; and microcytosis). Diagnosis is best achieved by coupling a liver function test (bile salts and/or NH3 quantitations) to a liver imaging technique, e.g., ultrasonography, scintigraphy, or contrast portal venography. Liver biopsy typically reveals portal venous hypoplasia, arterial smooth muscle hypertrophy, hepatocellular atrophy with lipogranulomas, and sometimes periportal sinusoidal dilatation. PROGNOSIS AND THERAPY - The prognosis is generally good if recognized early in the course of the disease. Cats are best managed with surgical attenuation or ligation of the shunting vessel. Some cats, especially those with incomplete attenuation of the shunt, may still require medical therapy following surgical repair.

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Wednesday, March 3, 2010 Thursday, March 4, 2010 Philadelphia, Pennsylvania

COMPANION ANIMAL: Gastrointestinal Issues

FELINE DIARRHEAL SYNDROMES: COMMON & NOT-SO-COMMON DISORDERS

Robert J. Washabau, VMD, PhD, DACVIM

Professor of Medicine and Department Chair, Department of Veterinary Clinical Sciences College of Veterinary Medicine, University of Minnesota St. Paul, MN

There are many potential causes of acute diarrhea in cats, but a smaller number of etiologies are associated with the development of feline chronic diarrhea. Primary intestinal diseases (malignancy, inflammatory bowel disease, food sensitivity, and infection) account for most of the causes of feline chronic diarrhea, but chronic diarrhea may also develop with extra-intestinal disease (hepatobiliary disease, exocrine pancreatic insufficiency, and hyperthyroidism). The syndrome of small intestinal bacterial overgrowth is an important cause of chronic diarrhea in the dog, but cats may be refractory to the development of this syndrome. Medical Investigation of Chronic Diarrhea ­ A systematic approach to the pathogenesis and etiology of chronic diarrhea (clinical signs persisting > 3 weeks) is clearly warranted. Most animals with acute diarrhea will resolve their clinical signs with minimal intervention. For those animals progressing to chronic diarrhea, a systematic approach will usually provide a definitive diagnosis and a rationale for therapy.

INFLAMMATORY BOWEL DISEASE (IBD)1-4

Chronic inflammation of the gastrointestinal tract (inflammatory bowel disease; IBD) is the most important cause of chronic diarrhea (and vomiting) in cats. Inflammatory bowel disease is not a single disease entity per se, but simply the culmination of chronic, sustained inflammation of the gut. A complete medical investigation should always be performed to consider all of the known causes of chronic diarrhea in the cat. A diagnosis of IBD is considered only after known causes (e.g., infection, toxicity, neoplasia, metabolic disorders, allergy/sensitivity reactions, maldigestion of exocrine pancreatic insufficiency) of chronic diarrhea have been carefully excluded. Clinical findings in feline IBD may include reduced body mass, thickened bowel loops, fever, abdominal pain, mesenteric lymphadenopathy, and, hepato/splenomegaly in cats with eosinophilic enteritis and hypereosinophilic syndrome. Hematologic and serum biochemical abnormalities are occasionally observed but are fairly non-specific. Abdominal radiographic and ultrasonographic studies are also usually non-diagnostic with occasional findings of fluid or gas-filled loops of bowel, intestinal wall abnormalities, and mesenteric lymphadenopathy.4 Intestinal biopsy (endoscopy or laparotomy) may help differentiate this spectrum of disorders from other known causes of enteritis.4 Dietary manipulation alone or in combination with drug therapies are the basis of therapy in this disorder. The prognosis is good for control in most cases, but not always curative.

INTESTINAL NEOPLASIA5-7

Lymphosarcoma, adenocarcinoma, and mast cell tumors are the most common tumors of the gastrointestinal tract in cats. Lymphosarcoma quite often involves diffuse segments of the bowel, whereas adenocarcinomas and mast cell tumors are usually more focal. Weight loss, anorexia, and diarrhea are the most important clinical signs. Intestinal lymphoma may develop over many months, and affected animals usually present with clinical signs of weight loss and diarrhea. Histologically, lymphosarcoma is usually characterized by diffuse mucosal and submucsoal infiltration of neoplastic lymphocytes. Malabsorption results from progressively reduced absorptive area in intestinal villi. Diffuse thickening of the small intestine and mesenteric lymphadenopathy are frequent physical examination findings, although these same findings can be observed in cats with moderate to severe inflammatory bowel disease. Ultrasonography is useful in evaluating intestinal thickness and mesenteric lymph nodes, but definitive diagnosis requires endoscopic or full thickness biopsies.

FOOD SENSITIVITY8-11

Adverse reactions to food (food sensitivities) include those mediated by the immune system (food allergies) and those without an immunological basis (food intolerances).9 Until recent times, objective evidence for food sensitivity has been somewhat lacking in the cat. Adverse reactions to food are usually suspected when an association is made between the

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ingestion of a certain food and the appearance of a clinical sign. The diagnosis is then confirmed by dietary eliminationchallenge studies.9 Alternative methods of diagnosis have been proposed in other species, including assay of serum antigen-specific IgE and gastroscopic food sensitivity testing. A commercial assay of cat antigen-specific IgE in serum is now available, but the sensitivity and specificity of the assay have not yet been determined. Gastroscopic food sensitivity testing has been applied to G.I. diagnosis in the dog, but has the distinct disadvantage of diagnosing just one type of food sensitivity ­ immediate type I hypersensitivity.10 In a recent study of 55 cats with chronic idiopathic gastrointestinal problems (diarrhea and/or vomiting for > 2 weeks), 29% of cats were diagnosed with food sensitivity based on dietary elimination/challenge studies.8 Another 20% of cats had resolution of clinical signs on the elimination diet but did not recur after challenge with their original diet. The foods or food ingredients responsible for the clinical signs were dietary staples (e.g., beef, wheat, and corn gluten). Fifty % of affected cats were sensitive to more than one food ingredient. Assays of serum antigen-specific IgE had limited value as screening tests, and gastroscopic food sensitivity testing was not helpful. The authors concluded that adverse reactions to dietary staples were common in their population of cats, and that affected cats responded well to selected-protein (e.g., chicken or venison-based) diets.8

EXOCRINE PANCREATIC INSUFFICIENCY12,13

Exocrine pancreatic insufficiency (EPI) is an uncommon cause of chronic diarrhea in cats. Insuffiency results from failure of synthesis and secretion of pancreatic digestive enzymes. The natural history of feline exocrine pancreatic insufficiency is poorly understood, but many cases are thought to result from chronic pancreatitis. As with dogs, clinical signs reported in cats with EPI include weight loss, soft voluminous feces, and greasy soiling of the haircoat. Affected cats may also have an antecedent history of recurring bouts of acute pancreatitis (e.g., anorexia, lethargy, vomiting) culminating in chronic pancreatitis and EPI.13 The diagnosis of EPI in cats has been technically difficult. Clinical signs in affected cats are not pathognomonic for EPI, clinicopathologic data are fairly non-specific, imaging findings are inconsistent, and the severity of pancreatic histologic changes are not always directly related to the severity of clinical signs. A feline-specific radioimmunoassay for trypsin-like immunoreactivity (TLI) has been developed, and a recent paper suggests that it may prove useful in the diagnosis of this disease.12 In that study, TLI concentrations less than 8 g/L (reference range = 17-49 g/L) were reported in 17/20 cats with clinical signs compatible with EPI (e.g., weight loss, loose voluminous feces, greasy soiling of the hair coat) and at least one other finding, e.g., decreased fecal proteolytic activity, exploratory laparotomy or necropsy findings compatible with EPI, or favorable response to pancreatic enzyme replacement therapy.12

HYPERTHYROIDISM14,15

Hyperthyroidism is a well-documented endocrine disorder of aging cats that is frequently accompanied by gastroenterologic signs, e.g., weight loss (88% of cats), polyphagia (49%), vomiting (44%), and diarrhea (15%).14 Clinical signs are related to the effects of thyroid hormone on metabolic rate and gastrointestinal motility. Diagnosis of feline hyperthyroidism is fairly straightforward, and involves the quantitation of serum thyroid hormones, T3 suppression test, TRH stimulation test, and/or radionuclide thyroid imaging.15 Chronic diarrhea associated with hyperthyroidism is readily reversible with appropriate therapy, e.g., thyroidectomy, 131I radiotherapy, or methimazole chemotherapy.15

HEPATOBILIARY DISEASE16,17

Cats experience several types of hepatobiliary disease including cholangiohepatitis, lymphocytic portal hepatitis, hepatic and biliary neoplasia, hepatic amyloidosis, and hepatic lipidosis. Diarrhea may be an important clinical sign in any of these disorders, particularly those with inflammatory liver disease. Cholangiohepatitis and lymphocytic portal hepatitis, for example, are frequently accompanied by gastroenterologic signs, e.g., anorexia (74%), weight loss (74 % of cats), vomiting (54%), and diarrhea (15%).17 Definitive diagnosis of any of these disorders requires the use of clinical pathology data, imaging studies (e.g., ultrasonography), and tissue biopsy. Clinical signs, laboratory data, and imaging findings are often quite similar between the various hepatobiliary disorders, thus histopathology is needed to differentiate these disorders.

CONCURRENT DISORDERS: CHOLANGIOHEPATITIS, PANCREATITIS, INFLAMMATORY BOWEL DISEASE18-21

Many cats have concurrent cholangitis, pancreatitis, and inflammatory bowel disease, and it may be difficult, if not impossible, to attribute individual clinical signs (e.g., diarrhea) to one organ system in affected cats.18-20 Pre-existing inflammatory bowel disease (IBD) likely contributes to the pathogenesis of pancreatitis and cholangiohepatitis in many, but perhaps not all, cats. There are several reasons, or contributing factors, for this association:

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1. High incidence of feline IBD ­ IBD is a common disorder in the domestic cat. In some veterinary hospitals and specialty referral centers, IBD is the most common gastrointestinal disorder in cats.4 2. Clinical symptomatology ­ Vomiting is the most important clinical sign in cats affected with IBD. Chronic vomiting predisposes cats to raised intra-duodenal pressure and pancreaticobiliary reflux. 3. Pancreaticobiliary anatomy ­ Unlike the dog, the sphincter of Oddi is a common (physiological and anatomic) channel at the duodenal papilla. Thus, reflux of duodenal contents perfuses both pancreatic and biliary systems.21 4. Intestinal Microflora ­ Compared to the dog, cats have a high much higher bacterial load (108 vs. 104 organisms/ml) in the proximal small intestine. Thus, duodenal reflux is theoretically more pathologic in the cat.22

GASTROINTESTINAL INFECTION 23-27

Any of the acute infectious diseases of the gastrointestinal tract can develop into chronic disease and/or carrier states. The most important of these are Campylobacter sp., Salmonella sp., Trichomonas sp., Toxocara sp., Toxoplasma sp., Cryptosporidium sp., Giardia sp., and feline corona (FIP), leukemia (FeLV), and immunodeficiency (FIV) viruses. Therefore, the routine medical investigation of any cat affected with chronic diarrhea should include direct and indirect fecal examinations for helminths (Toxocara) and protozoa (Toxoplasma, Giardia, Trichomonas, Cryptosporidium), bacterial culture of feces (Salmonella, Campylobacter), and serologies (FeLV, FIV, Toxoplasma, Cryptosporidium). It should be pointed, however, that cats with chronic diarrhea do not necessarily have a greater incidence of any of these infectious 23,25 In other words, a positive result agents when compared to healthy cats without diarrhea or other G.I. clinical signs. does not necessarily imply that the infectious agent is the underlying cause of the clinical signs.

SMALL INTESTINAL BACTERIAL OVERGROWTH (SIBO)?22,28,29

Small intestinal bacterial overgrowth (SIBO) is a syndrome of dogs and humans associated with the proliferation of aerobic and/or anaerobic bacteria of the small intestine, and the subsequent development of related clinical signs, e.g., diarrhea, weight loss, and vomiting. Clinical signs result from bacterial metabolism of exogenous and endogenous intraluminal constituents, and from the production of metabolites (e.g., deconjugated bile acids and hydroxylated fatty acids) with adverse effects on the intestinal or colonic mucosa. Dogs with this syndrome appear to respond to appropriate short courses of antibiotics. It has been suggested that SIBO might occur in cats, as well, but the evidence is not very compelling. Indeed, a recent study showed no differences in the aerobic, anaerobic, or total bacterial populations in the small intestine of cats with chronic G.I. 28 disease vs. bacterial populations in the intestine of healthy cats. It has been suggested that host defenses to indigenous flora may be particularly well developed in the feline proximal small intestine, and that the species may be resistant to bacterial overgrowth.28

REFERENCES

INFLAMMATORY BOWEL DISEASE 1. Jergens AE, Moore FM, Haynes JS, et al. Idiopathic IBD in dogs and cats. J. Amer. Vet. Med. Assoc. 1992; 201: 1603-1608. 2. Hart JR, Shaker E, Patnaik AK, et al. Lymphocytic-plasmacytic enterocolitis in cats. J. Amer. Anim. Hosp. Assoc. 1994; 30: 505-514. 3. Dennis JS, Kruger JM, Mullaney TP. Lymphocytic/plasmacytic colitis in cats. J. Amer. Vet. Med. Assoc. 1993; 202: 313318. 4. Baez JL, Hendrick MJ, Walker LM, Washabau RJ. Radiographic, ultrasonographic, and endoscopic findings in cats with inflammatory bowel disease of the stomach and small intestine. J. Amer. Vet. Med. Assoc. 1999, 215: 349-354. INTESTINAL NEOPLASIA 5. Straw RC. Tumors of the intestinal tract. In, Small Animal Clinical Oncology, Withrow SJ and MacEwen EG, editors. WB Saunders, Philadelphia, 1996, pp. 252-278. 6. Kosovsky JE, Matthiesen DT, Patnaik AK. Small intestinal adenocarcinoma in cats. J. Amer. Vet. Med. Assoc. 1988; 192: 233-235. 7. Head KW, Else RW. Neoplasia and allied conditions of the canine and feline intestine. Vet. Ann. 1981; 21: 190-208.

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FOOD SENSITIVITY 8. Guilford WG, Jones BR, Markwell PJ, et al. Food sensitivity in cats with chronic idiopathic gastrointestinal problems. J. Vet. Intern. Med. 2001; 15: 7-13. 9. Hall EJ. Gastrointestinal aspects of food allergy: a review. J. Small Anim. Practice 1994; 35: 145-152. 10. Guilford WG, Strombeck DR, Rogers Q, et al. Development of gastroscopic food sensitivity testing in dogs. J. Vet. Intern. Med. 1994; 8: 414-422. 11. Paterson S. Food sensitivity in 20 dogs with skin and gastrointestinal signs. J. Small Anim. Practice 1995; 36: 529-534. EXOCRINE PANCREATIC INSUFFICIENCY 12. Steiner JM, Williams DA. Serum feline trypsin-like immunoreactivity in cats with exocrine pancreatic insufficiency. J. Vet. Intern. Med. 2000; 14: 627-629. 13. Steiner JM, Williams DA. Feline exocrine pancreatic disorders. Vet. Clin. North America 1999; 29: 551-575. HYPERTHYROIDISM 14. Broussard J, Peterson ME. Changes in clinical and laboratory findings in cats with hyperthyroidism from 1983-1993. J. Amer. Vet. Med. Assoc. 1995; 206: 302-306. 15. Peterson ME. Hyperthyroidism. In, Textbook of Veterinary Internal Medicine, Ettinger SJ and Feldman EC, editors. WB Saunders, Philadelphia, 2000, pp. 1401-1419. HEPATOBILIARY DISEASE 16. Gagne JM, Weiss DJ, Armstrong PJ. Histopathologic evaluation of feline inflammatory liver disease. Vet. Pathol. 1996; 33: 521-526. 17. Weiss DJ, Armstrong PJ, Gagne J. Inflammatory liver disease. Sem. Vet. Med. Surg. 1997; 12: 22-27. CONCURRENT DISORDERS: Pancreatitis, Cholangiohepatitis, and IBD 18. Weiss DJ, Gagne JM, Armstrong PJ. Relationship between inflammatory hepatic disease and IBD, pancreatitis, and nephritis in cats. J. Amer. Vet. Med. Assoc. 1996; 209: 1114-1116. 19. Hill RC and Van Winkle TJ. Acute necrotizing pancreatitis and acute suppurative pancreatitis in the cat. J. Vet. Intern. Med. 1993; 7: 25-33. 20. Akol KG, Washabau RJ, Saunders HM, et al. Acute pancreatitis in cats with hepatic lipidosis. J. Vet. Intern. Med. 1993; 7: 205-209. 21. Thune A, Friman S, Conradi N, et al. Functional and morphological relationships between the feline main pancreatic and bile duct sphincters. Gastroenterology 1990; 98: 758-765. 22. Johnston KL, Lamport A, Batt RM. An unexpected bacterial flora in the proximal small intestine of normal cats. Vet. Rec. 1993; 132: 362-363. GASTROINTESTINAL INFECTION 23. Hill SL, Cheney JM, Taton-Allen GF, et al. Prevalence of enteric zoonotic organisms in cats. J. Amer. Vet. Med. Assoc. 2000; 216: 687-692. 24. Gookin JL, Breitschwerdt EG, Levy MG, et al. Diarrhea associated with trichomonosis in cats. J. Amer. Vet. Med. Assoc. 1999; 215: 1450-1454. 25. Spain CV, Scarlett JM, Wade SE, et al. Prevalence of enteric zoonotic agents in cats less than 1 year old in central New York State. J. Vet. Intern. Med. 2001; 15: 33-38. 26. Kirkpatrick CE, Green GA. Susceptibility of domestic cats to infections with Giardia lamblia cysts and trophozoites from human sources. J. Clin. Microbiol. 1985; 21: 678-680. 27. Mtambo MMA, Nash AS, Blewett DA, et al. Cryptosporidium infection in cats: prevalence of infection in domestic and feral cats in the Glasgow area. Vet. Rec. 1991; 129: 502-504. SMALL INTESTINAL BACTERIAL OVERGROWTH? 28. Johnston KL, Swift NC, Forster-van Hijfte M, et al. Comparison of the bacteria flora of the duodenum in healthy cats and cats with signs of gastrointestinal tract disease. J. Amer. Vet. Med. Assoc. 2001; 218: 48-51. 29. Johnston KL, Lamport Al, Ballevre OP, et al. Effects of oral administration of metronidazole on small intestinal bacteria and nutrients of cats. Amer. J. Vet. Res. 2000; 61: 1106-1112.

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Wednesday, March 3, 2010 Thursday, March 4, 2010 Philadelphia, Pennsylvania

COMPANION ANIMAL: Dermatology

FOOD ALLERGY - WHAT YOU KNOW, WHAT YOU DON'T KNOW, AND WHAT YOU SHOULD KNOW

Anthony Yu, DVM, MS, DACVD

Associate Professor, Dermatology University of Guelph, Ontario Veterinary College Guelph, ON, Canada The term food allergies has been used indiscriminately to describe any type of reactions to ingested food items or its constituents, when in fact, food allergies should be reserved for immunologic-based hypersensitivities. The ACVD classifies any aberrant reaction after ingestion of food or additive as an Adverse Food Reactions (AFR). AFRs have thus been further classified as follows: I) Food Hypersensitivities (immunologic adverse reactions) a) Food allergies ­ IgE-mediated reactions or Type I hypersensitivity b) Non-IgE mediated hypersensitivity ­ Type III and/or IV hypersensitivity II) Food intolerance - non-immunologic adverse reactions a) Food-dependent factors ­ toxins/poisoning or contaminants b) Host-dependent factors ­ enzyme deficiencies, drug reactions, idiosyncrasies The major food allergens are heat-stable, water soluble glycoproteins of molecular weights between 10 to 70 kilodaltons, however peptides as small as 3 to 5 kd may be allergenic. Proteins greater than 70 kd are too large to be absorbed through intact enteric mucosa and hence are not thought to be allergenic.

SIGNALMENT

Recent studies indicate that AFRs account for 32.7% and 10-23% of allergic conditions in dogs and cats respectively. Signalment may in some cases be helpful to at least help increase your index of suspicion of AFR in pets. Tops breeds associated with food allergy in the author's experience include Labrador retrievers and cocker spaniels, along with others described in literature including, but not exclusively, the Soft-Coated Wheaton Terrier, Dalmatian, West-Highland White Terrier, Bichon frisee, Collie, Chinese Shar Pei, Llasa apso, Dachshund, Miniature Schnauzer, Boxer, Springer Spaniel, Cairn Terrier, Irish/English Setter, Golden retriever, German shepherd dogs, along with Siamese and Birman cats. Age at presentation is typically less than one year (2 months to 16 years; 33-52%) in dogs and before 2 years (4 months to 15 years; 38.5%) in cats. In general, food allergy should be strongly considered in any pet that develops pruritus/clinical signs prior to 6 months and after 6 years of age with no previous history of cutaneous disease. In all the studies thus far, there appears to be no sex predilection.

HISTORY

Non-seasonal pruritus is the most common clinical manifestation of food allergy and the reason for seeking veterinary attention in most cases. Food allergy is often associated with other pruritic dermatopathies including atopy, flea allergy and superficial staphylococcal pyoderma. Simultaneous occurrence of food allergy with atopy or flea allergy may cause a non-seasonal condition with seasonal peaks. Food allergic patients' response to conventional anti-inflammatory doses of glucocorticoids is minimal in most cases. The association of sudden dietary change with onset of clinical signs is more the exception than the rule. In fact, 70% of patients with food hypersensitivity had been exposed to the allergen for over 2 years before becoming clinically symptomatic. Pets can be allergic to one or more antigens in a diet. Generating an inventory or current and previous commercial pet foods, table foods, snacks, treats, drive-thru rewards, chewable medications and digestible chew toys (e.g. rawhides) should be part of the historical database. Specific questions regarding gastrointestinal disturbance should likewise be addressed in the acquisition of proper history. Episodic food hypersensitivity may occur following intermittent exposure to the offensive diet from the table, from predation, or eating garbage. This is especially true of cats since owners tend to buy more variety of canned cat foods. Coprophagic dogs may obtain undigested material that could affect a food allergy.

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CLINICAL SIGNS

Cutaneous findings Although the most common clinical sign of food allergy is pruritus, it is not present in every case. Erythema with a papular eruption is also commonly observed. Urticaria and angioedema are less common clinical signs. Secondary scale and crust is often present and may be a primary owner complaint. Malodor is typically noticed when oiliness is present along with recurrent secondary bacterial or Malassezia dermatitis The ear region was most consistently involved (80%) followed by the feet (61%) and the inguinal/perineal region (53%) in a study evaluating AFR in dogs. The axillary, anterior foreleg and periorbital regions were nearly equal in occurrence (31-37%). The ear was the only area affected in 12 dogs (24%). Another pattern of clinical signs is similar to flea allergy dermatitis affecting the lower back, tailhead region and caudolateral thighs. When the dorsal lesions extend beyond the thoracolumbar junction over the chest area, this also increases my index of suspicion for food allergy, as not many other diseases affect this region. AFR has to be considered among the top differentials for acral lick dermatoses, along with neurologic root-based conditions, behavioural obsessive compulsive disorders, arthritic pain if lesion is noted over a joint, hypothyroidism, environmental allergies, demodicosis and secondary fungal, bacterial or yeast infections. Lastly, perianal pruritus is almost exclusively due to food allergy when considering allergic etiologies. CAFR in cats can present with similar distribution to those in dogs, however the head and neck (ring around the collar) appears more commonly affected than the ears, feet and rears. Other cutaneous conditions that may be attributable to or triggered by AFR include Cocker Spaniels idiopathic seborrhea, symmetric lupoid onychodystrophy, sterile interdigital cysts, feline eosinophilic granuloma complex, feline symmetric (fka psychogenic) alopecia, feline miliary dermatitis, chin acne, pemphigus complex, perianal fistulas, pinnal vasculitis, recurrent generalized demodicosis, and food-induced cutaneous vasculitis. Gastrointestinal (GI) signs Concurrent gastrointestinal signs are present in up to 32% of food allergic patients. These include vomiting, changes in the stool consistency, increased frequency of bowel movements, eructations, halitosis, borborygmus, flatulence, tenesmus, eosinophilic or lymphocytic-plasmacytic colitis/IBD, anal gland impaction & scooting, pica and/or coprophagia.

OTHER RELATED SIGNS

Neurologic/behavioral signs such as malaise, seizures, attention deficit disorders, difficulty in training, behavior changes and dominance aggression have either been proposed, documented or are currently being researched. Respiratory signs associated with AFR include asthma, rhinitis and sinusitis. Musculoskeletal conditions potentially attributable to food allergies include sterile polyarthritis and masticatory muscle myosisits. Concurrent conditions noted with frequency include environmental, flea, intestinal parasite and insulin hypersensitivities, secondary recurrent pyoderma and Malassezia pachydermatis infection (may be the only sign) and Sarcoptes infestation.

DIAGNOSIS

It is important to eliminate/address concurrent conditions, especially atopy and scabies, before or while on dietary trial. I find that voicing the "treat list" aloud to owner will help to accurately catalog dietary ingredients, as some owners do not feel that the monthly heartworm preventative is a "treat". I usually start with an open-ended question such as "what crosses your pet's mouth during the course of a week?" and follow it with my checklist including the following: treats and rawhide chews, toys, drive-thru treats (Timbits...), goodies from the neighbour/service person, popcorn, tuna juice, end-ocereal/ice cream bowl, access to other pet's food or stool, pilling vehicles/devices (pill pockets, cheese, etc), supplements (chondroitin/GAG), alternative medications (Echinacea), flavoured toothpaste, and/or chewable medications. I also include fruits and vegetables on my checklist, as a condition called Oral Allergy Syndrome has been documented in humans whereby ingestion of oral antigens from various food items may have similar antigenic protein (e.g. Bet v1 in birch and apple; cedar pollen and raw tomato) or may cross-react with environmental allergens to escalate clinical signs of the consumer's atopic condition. The use of either a RAST (radioallergosorbent test) or an ELISA (enzyme linked immunosorbent assay) technique for evaluating circulating IgE levels is commercially available. Although the advantage of these tests is obvious, their correlation to actual food hypersensitivity is not known. In fact, serum IgG may correlate better with clinical disease. There have been reports in humans with good correlation between in vitro test procedures, skin testing and food allergy. This has

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not been documented in veterinary medicine. In contrast, studies performed suggest the lack of correlation between food allergy, RAST or ELIZA results, gastroscopic food sensitivity testing, colonoscopic allergen provocational studies (COLAP) and in vivo intradermal allergy test results. Positive predictive values were recently determined to be 40% whereas the negative predictive values were 60.9%. The overall consensus of most dermatologists is that dietary trials are a more effective method of diagnosis. Standardizing a diet based upon in vitro test results provides minimal advantage over empirical decision without prior testing.

DIETARY RESTRICTION

Confirmation of food allergy can only be determined by an elimination trial. The diet is restricted to specific food determined by the animal's previous exposure and known reactions. Food items most commonly causing food allergy include beef, milk, lamb, wheat, corn, chicken egg, soy, chicken in dogs, adding tuna and salmon to the list in cats. The preferred diet is home prepared and simplified to include a protein source and a carbohydrate source (1:2). The primary objective is to select a food combination that has minimal or no history of previous exposure. This may require reviewing the list of ingredients of commercial dog/cat foods and treats. Although lamb and rice has been in vogue for dietary trials for some time, the prevalence of these substances in commercial feed is limiting its usefulness and an increase in dietary related skin disease has been associated with lamb & rice based foods. Novel protein sources currently available for home-cooking include kangaroo, camel, ostrich, emu, bison, elk, venison, rabbit, duck, fish, whole chicken egg as well as lamb. Old world grains such as spelt along with oatmeal, quinoa, rutabaga, sweet potato and white potatoes have taken the place of rice as a result of its gluten and popularity in commercially prepared diets. Tofu has been used successfully in home-prepared foods but has two major disadvantages. The first is the poor palatability and the second is the low caloric density failing to provide adequate satiety. Tofu is composed of soybean, which restricts its use if the commercial food contains soy. Cats may pose difficulties in performing dietary trials as they have finicky appetites and easily become bored with the diet following initiation of the trial. Keeping cats indoors may prove difficult for some cat owners, as well as eliminating the access of house foods from the table or garbage due to cat's ability to leap onto various surfaces. Supplementation with a multivitamin is not necessary for the length of the trial. If concerns arise about young growing dogs or cats placed on a home-prepared elimination diet, an option is to select one of the commercial foods. Any vitamin/mineral supplement during an elimination trial should be the non-chewable variety. Consulting with nutritionists for advice about specific breed requirements may be helpful. Owners will often wish to provide treats to their pets during the elimination diet. Using the same or similar ingredients as the main diet provides an option that does not compromise the trial. The most difficult part of the trial is avoidance of any other food. Pitfalls include multiple dog/cat households where access of another food occurs. Table foods fed by children is a concern since it would invalidate the test. Fallen food from the high chair may also disrupt the dietary trial. Although it is advantageous to utilize home-prepared diets, the 8-12 week duration of the trial along with sufficient availability of commercial foods to conduct a good trial often leads owners to abandon home-cooked diets. The selection of the single protein and carbohydrate source should ultimately be based on the dietary history of the animal. The selection of a food with limited ingredients is the next priority. A large variety of dog foods exist based upon different novel and hydrolyzed protein sources. The use of a commercial food provides a conservative way of evaluating food allergy although it has some compromise compared to a home-prepared fresh food because of multiple ingredients and additives present. Monthly evaluation of response to the dietary elimination trial is mandatory. I often preface the start of a dietary trial with "It should only get better, it should not get worse". If clinical signs deteriorate anytime before the initial 4-week recheck, the owner should discontinue the diet and other ancillary medications, allow the reactions to calm and switch to a different diet. During the time of the dietary trial, it is also important to control coexistent factors that may potentiate the pruritus and obscure the results such as flea allergy dermatitis, Malassezia dermatitis and superficial pruritic pyoderma. I also often include glucocorticoid therapy during the first 30-45 days of the dietary trial to control intense pruritus and self-mutilation. After this time, the steroids are terminated, the restricted diet is continued, and the patient continues to be evaluated. The confirmation of food allergy can only be made following optimal improvement of the case and conducting dietary challenge. Challenge most often uses the single most common diet fed prior to the elimination trial. Some owners may be

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reluctant to institute a dietary challenge particularly if the improvement has been great. It is important to follow through with careful monitoring of the dietary challenge. Observing the recurrence of the pyoderma, gastrointestinal, neurologic, behavioural, musculoskeletal and/or respiratory symptoms upon food challenge is evidence of the relationship. Relapses typically occur within 15 minutes to 14 days (12-48 hrs most commonly). In the event of relapse during the challenge, the pet should be returned to the elimination diet for a period of time to return to the pre-challenge level of clinical signs before adding another test food. Return to pre-challenge level takes much less time than the original response noted during the original trial.

CONCLUSION

Omission of food allergy as an important differential is an omission of our oath to "Above all, do no harm!" It is one of the easier immune-mediated diseases to control by means of avoidance. In fact, AFR should always be considered a potential trigger/underlying factor, as alternative lifelong immunomodulatory therapies or surgeries in a dog or cat may pose a significant health risk. What have you got to lose by considering a diet trial for: a) Inflammatory Bowel Disease vs lifelong steroids and immunosuppressive agents b) Anal gland disease vs surgery and its complications c) Asthma vs chronic anti-inflammatory medications d) Chronic recurrent otitis externa vs. Total Ear Canal Ablation-Bulla Osteotomy e) Idiopathic epilepsy vs lifelong Phenobarbital, potassium bromide or Keppra® (levetiracetam) f) Behavioural disorders (ADD, Aggression) vs. lifelong behaviour modifying agents or euthanasia g) Immune-mediated disease vs lifelong immunosppressive therapies and repeated bloodwork to monitor for adverse effects Again, I ask you, what have you got to lose by performing a dietary trial?

RECOMMENDED READING

Allenspach K, Vaden SL, Harris TS, et al. Evaluation of colonoscopic allergen provocation as a diagnostic tool in dogs with proven food hypersensitivity reactions. J Small Anim Pract. January 2006;47(1):21-6. Allenspach K, Rüfenacht S, Sauter S, et al. Pharmacokinetics and clinical efficacy of cyclosporine treatment of dogs with steroid-refractory inflammatory bowel disease. J Vet Intern Med. 2006 Mar-Apr;20(2):239-44. Allenspach K, Rüfenacht S, Sauter S, et al. Pharmacokinetics and clinical efficacy of cyclosporine treatment of dogs with steroid-refractory inflammatory bowel disease. J Vet Intern Med. 2006 Mar-Apr;20(2):239-44. Allenspach K, Bergman PJ, Sauter S et al. P-glycoprotein expression in lamina propria lymphocytes of duodenal biopsy samples in dogs with chronic idiopathic enteropathies. J Comp Pathol. January 2006;134(1):1-7. Bach JF. The effect of infections on susceptability to autoimmune and allergic diseases. N Engl J Med. 2002;347;12:911-920 Bailey M, Haverson H, Inman C et al. The development of the mucosal immune system pre- and post-weaning: balancing regulatory and effector function. 2005;64:451-457. Biourge VC, Fontaine J, Vroom MW. Diagnosis of adverse reactions to food in dogs: efficacy of a soy isolate hydrolysate based diet. J Nutr 2004; 134: 2062S-2064S. Chehade M and Mayer, L. Oral tolerance and its relation to food hypersensitivites. J Allergy Clin Immunol. 2005;115:3-12. Chesney CJ. Food sensitivity in the dog: a quantitative study. J Small Anim Pract. May 2002;43(5):203-7. Cianferoni A and Spergel, JM. Food Allergy: Review, Classification and Diagnosis. Alerology International. 2009;58:1-10. Eigenmann PA. Mechanisms of food allergy. Pediatric Allergy and Immunology. 2009;20:5-11. Foster AP, Littlewood JD, Webb P, et al. Comparison of intradermal and serum testing for allergen-specific IgE using a Fcepsilon RIalpha-based assay in atopic dogs in the UK Vet Immunol Immunopathol. May 2003;93(1-2):51-60.

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Fujimura M, Ohmori K, Masuda K, et al. Oral allergy syndrome induced by tomato in a dog with Japanese cedar (Cryptomeria japonica) pollinosis. J Vet Med Sci. November 2002;64(11):1069-70. Gilbert S, Halliwell REW. The effects of endoparasitism on the immune response to orally administered antigen in cats. Vet Immunol Immunopathol. June 2005;106(1-2):113-20. Guilford WG, Strombeck DR, Rogers Q, et al. Development of gastroscopic food sensitivity testing in dogs. J Vet Intern Med. 1994 Nov-Dec;8(6):414-22. Guilford WG, Jones BR, Markwell PJ, et al. Food sensitivity in cats with chronic idiopathic gastrointestinal problemsJ Vet Intern Med. 2001 Jan-Feb;15(1):7-13. Halliwell REW, Gordon C, Horvath C et al. IgE and IgG antibodies to food antigens in sera from normal dogs, atopic dogs and dogs with adverse food reactions. Vet Derm 2004 15 (Suppl.1) 2. Ishida R, Masuda K, Sakaguc M, et al. Antigen-specific histamine release in dogs with food hypersensitivityJ Vet Med Sci. March 2003;65(3):435-8. Ishida R, Masuda K, Kurata K, et al. Lymphocyte blastogenic responses to inciting food allergens in dogs with food hypersensitivityJ Vet Intern Med. 2004 Jan-Feb;18(1):25-30 Jackson HA, Hammerberg B. The clinical and immunological reaction to a flavoured monthly oral heartworm prophylatic in 12 dogs with spontaneous food allergy. Vet Derm 2002;13(4):211-229 Jackson HA, Jackson MW, Cobletz L, Hammerberg B. Evaluation of clinical and allergen specific serum immunoglobulin E response to oral challenge with cornstarch, corn, soy and soy hydrolysate diet in dogs with spontaneous food allergy. Vet Derm 2003; 14:181-187. Kawakami T, Ando T, Kimura M et al. Mast cells in Atopic Dermatitis. Curr Opin in Immunol. 209;21:1-13. Jeffers JG, Meyer EK, Sosis EJ. Responses of dogs with food allergies to single-ingredient dietary provocation.J Am Vet Med Assoc. August 1996;209(3):608-11. Kunkle G, Hrner S. Validity of skin testing for diagnosis of food allergy in dogs J Am Vet Med Assoc. March 1992;200(5):677-80. Loeffler A, Lloyd DH, Bond R, st al. Dietary trials with a commercial chicken hydrolysate diet in 63 pruritic dogs. Vet Rec 2004; 154:519-522. Loeffler A, Soares-Magalhaes R, Bond R, et al. A retrospective analysis of case series using home-prepared and chicken hydrolysate diets in the diagnosis of adverse food reactions in 181 pruritic dogs. Vet Derm 2006; 17:273-279. Luckschander N, Allenspach K, Hall J, et al. Perinuclear antineutrophilic cytoplasmic antibody and response to treatment in diarrheic dogs with food responsive disease or inflammatory bowel disease. J Vet Intern Med. 2006 Mar-Apr;20(2):221-7. Martin A, Sierra MP, González JL et al. Identification of allergens responsible for canine cutaneous adverse food reactions to lamb, beef and cow's milk. Vet Derm 2004; 15(6):349-356 Masuda K, Sakaguchi M, Fujiwara S, et al. Positive reactions to common allergens in 42 atopic dogs in Japan.Vet Immunol Immunopathol. February 2000;73(2):193-204. Mueller R, Tsohalis J. Evaluation of serum allergen-specific IgE for the diagnosis of food adverse reactions in the dog. Vet Derm 1998;9(3):pp. 167-171 Mueller LSC. T cell-mediated immunoregulation in the gastrointestinal tract. Allergy. 2009;64:505-519.

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Nauta AJ, Engels F, Knippels LM, et al. Mechanisms of allergy and asthma. European Journal of Pharmacology. 2008;585:354-360. Ohashi K, Sato Y, Iwata H, et al. Colonic mast cell infiltration in rats with TNBS-induced visceral hypersensitivity. J Vet Med Sci. December 2007;69(12):1223-8. Ohmori K, Masuda K, Kawarai S, et al. Identification of bovine serum albumin as an IgE-reactive beef component in a dog with food hypersensitivity against beef. J Vet Med Sci. August 2007;69(8):865-7. Puigdemont A, Brazis P, Serra M, et al. Immunologic response against hydrolysed soy protein in dogs with experimentally induced soy hypersensitivity. Am J Vet Res 2006; 67:484-488. Rosser EJ: Food allergy in the cat: a prospective study of 13 cats. In: Ihrke PJ, Mason I, White SD, eds. Advances in Veterinary Dermatology Vol 2. Oxford: Pergamon Press, 1993; 33-9. Rosser, EJ. Diagnosis of food allergy in dogs. JAVMA 1993; 203: 259-262. Sauter SN, Benyacoub J, Allenspach K, et al. Effects of probiotic bacteria in dogs with food responsive diarrhoea treated with an elimination diet. J Anim Physiol Anim Nutr (Berl). August 2006;90(7-8):269-77. Serra M, Brazis P, Fondati A, et al. Assessment of IgE binding to native and hydrolysed soy protein in serum obtained from dogs with experimentally induced soy protein hypersensitivity. Am J Vet Res 2006; 67: 1895-1900. Stogdale L, Diehl G. In support of bones and raw food diets CVJ. 2003;44(10):783; author reply 783-4. Van Putten MC, Frewer LJ, Gilissen LJWJ, et al. Novel foods and food allergies: A review of the issues. Trends in Food Science & Technology, Volume 17, Issue 6, June 2006, Pages 289-299 Waisglass SE, Landsberg GM, Yager JA, et al. Evaluation of 21 cats with a presumptive diagnosis of psychogenic alopecia. Vet Dermatol. June 2006;17(3):219. White SD. Food hypersensitivity in 30 dogs. J Am Vet Med Assoc. April 1986;188(7):695-8.

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COMPANION ANIMAL: Dermatology

CANINE OTITIS EXTERNA: CONTROVERSIES, CONCEPTS AND NEW APPROACHES TO STUBBORN EARS

Anthony Yu, DVM, MS, DACVD

Associate Professor, Dermatology University of Guelph, Ontario Veterinary College Guelph, ON, Canada Otitis externa is a common presenting complaint in veterinary and referral practice. The prevalence of otitis externa in dogs is 10-20%, perhaps as high as 30-40% in tropical and subtropical environments. Otitis in the cat is much less common, with a prevalence of 2-10%, depending on the study population. Many controversies exist even within the dermatologic community. Often, character and smell of the discharge, along with bacterial culture and sensitivity testing are common procedures used in the diagnosis of otitis externa, and as such veterinarians frequently rely on them to select antibiotic therapy for bacterial otitis externa and anti-yeast therapy for Malassezia otitis externa.

DIAGNOSING OTITIS EXTERNA

In this day of communicable/zoonotic, methicillin-resistant and other bacteria, it is advisable to AVOID sniffing infected ears, as it does not provided accurate information anyway. Diagnostically, I tend to rely primarily on otic examination and ear cytology. Otic examination provides a rapid means of diagnosing ear mites, tumours and foreign bodies, as well as providing a clinical baseline from which to correlate laboratory diagnostics with clinical relevance (e.g. purulent ulcerated ear would be consistent with rod-shaped bacteria on cytology and Pseudomonas aeruginosa on otic culture). Use of video-otoscopy (MedRx, Storz) enhances the clinician's ability to visualize the entire ear canal magnifying the image 22 times over that of a handheld otoscope. As well, video-otoscopy provides a wide-angled view that the clinician, the technician and client can appreciate on a monitor. Otic cytology is quantitative, giving the clinician a rapid indication of the relative number of morphologically different species present in the ear at that time which may aid in empirical selection of otic therapy. Discordance between cytology and otic cultures has also been reported by Graham-Mize, and for this reason, it must be emphasized that otic cultures should always be interpreted in light of concurrent cytology done by the clinician at the time of sampling, and the results of both these diagnostic tests should be interpreted in light of the otic examination. As well, otic cultures are fraught with many challenges and controversies: 1) They provide sensitivity information regarding systemic and not topical delivery of medications 2) Bacteria and yeast usually multiply to large numbers in abnormal ear canals, but the ability to culture large numbers of one or more microorganisms does not necessarily demonstrate the relevance to the disease process e.g. mixed infection with Enterococcus. 3) Most laboratories do not perform sensitivity spectrums on yeast/fungi 4) Consistency of sampling technique such as small numbers of organisms submitted; variability in transport conditions; sample processing and culture technique; laboratory variation in definitions of susceptibility; and/or variation in laboratory techniques or interpretation. 5) The overgrowth of one bacteria by another or the presence of heteroresistant strain may complicate the picture especially when 49.4% of cultures demonstrate greater than two bacterial species present and 27.3% with three or greater isolates present per specimen (n=176) 6) Three individual studies by Griffin, Graham-Mize & Rosser, and Schick et al revealed that inherent inconsistencies/lack of repeatability BETWEEN and WITHIN laboratories For these reasons, I tend to only pursue otic bacterial culture and sensitivity when: 1) The infection has failed to respond to appropriate medication despite good owner compliance indicating a potential resistant bacteria (MRSA, MRSS, MRSI). e 2) When otitis media is present (head tilt), specially if systemic antibiotics are to be used. NB: Stop all therapy for at least 72 hours prior to culturing.

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TREATMENT OF OTITIS EXTERNA

The inflamed ear is an extremely moist and warm environment with readily available nutritional sources and often with a compromised epithelium. Under these conditions, the ear canal is extremely favourable to bacterial and yeast growth, including for species that otherwise are not present and are simply unable to reproduce successfully in the normal ear canal (e.g. Pseudomonas spp., Enterococcus spp.). Chronicity of ear disease often worsens this problem. Hence, the threepronged concept is key to successful treatment of ALL cases of otitis externa: 1) Identify and address the underlying etiology 2) Identify and treat the secondary infection 3) Calm the microenvironment such that it is not conducive for bacterial or yeast overgrowth My top three underlying etiologies once I have eliminated Otodectes, foreign body and neoplasia by my otic examination, include adverse food reactions, environmental allergies and hypothyroidism. Hypothyroidism causes a ceruminous otitis externa with alterations in cerumen lipid composition to low levels of free fatty acids in surface lipids coupled with increased levels of surface triglycerides acts as fodder to the microorganisms that are also allowed to propagate and establish and infection as a result of the compromised immune system. Other clinical symptoms of hypothyroidism may or may not be noted, hence a thyroid profile is often used to support the clinical diagnosis and establish a basis for supplementation. Rosser reported that up to 24% of adverse food reaction patients present with otitis externa as their only clinical complaint. It behooves us therefore, to consider a dietary restriction using limited ingredient novel or hydrolyzed protein sources in patients with recurrent otitis externa. Environmental allergies should be a serious consideration in a patient that started with a history of seasonally recurrent otitis externa. Allergy testing and immunotherapy or symptomatic medical management may result in control of the otitis externa without the need for otic therapy. The "routine" otitis externa Many topical products contain an antiyeast, antibacterial and anti-inflammatory agents...a shotgun approach. In general, these products work well for uncomplicated first and even repeated cases of otitis externa. Knowledge of the active ingredients within these products will help with selection of the appropriate therapy for your patient. Selection is based on otic examination, otic cytology and correlation with the degree of clinical involvement. My favourite otic treatment ingredients are as follows: Topical antiyeast Topical antibiotic Topical anti-inflammatory Clotrimazole Enrofloxacin* Fluocinolone Enilconazole Polymyxin B Betamethasone Miconazole Gentamicin** Prednisone *NB: Marbofloxacin topically combined with dexamethasone and clotrimazole should be available in near future. **NB: neomycin has been implicated as a contact sensitizer in the ear and hence its use should be limited. Systemic antiyeast Systemic antibiotic Systemic anti-inflammatory Ketoconazole Fluoroquinolones Dexamethasone Itraconazole Beta-lactams Prednisolone Fluconazole Aminoglycosides Cyclosporine The "resistant" Pseudomonas otitis 1) Address underlying etiology 2) Calm the ear canal i) topical and/or (immunosuppressive) systemic steroids or cyclosporine ­ extremely important!!! 3) Increase cell wall permeability to antimicrobials Tris-EDTA (T8 Solution®, Triz-EDTA®) i) Tris = Surfactant product peptidoglycan membrane & binding destructive elastase enzyme - maintains pH of 8.0, optimum for function of the aminoglycosides and fluoroquinolones ii) EDTA = Ca/Mg binding agent decreased membrane integrity at porins influx of antibiotic iii) Cleanse ears BID, let stand 15 minutes before adding medications 4) Follow with topical antimicrobial treatment (100-1000X systemically delivered concentrations) i) Steroid (Synotic®, dexamethasone): enrofloxacin (Baytril® injectable 50 mg/ml) (24 cc: 6cc) - instill 0.25-1.0cc BID OR ii) Steroid (Synotic®, dexamethasone): enrofloxacin/silversulfadiazene (Baytril Otic®) (1:1) - instill 0.25-1.0cc BID until negative cytology +/- negative culture depending on chronicity of the otitis.

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iii) Systemic antibiotics (based on culture and sensitivity findings) IF signs of otitis media are present. The "severe" Malassezia otitis 1) Address underlying etiology 2) Calm the ear canal i) Topical and/or (immunosuppressive) systemic steroids or cyclosporine ­ extremely important!!! 3) Cleanse ear to remove irritating cerumen/debris and allow medications to reach the organisms i) Cleanse ears once daily with a cerumenolytic agent 4) Follow with anti-yeast treatment i) Steroid (Synotic®, dexamethasone): Enilconazole (Imaverol®) or miconazole (Confite®) (1:1) - instill 0.25-1.0cc BID for 30 days OR ii) Silversulfadiazene (Baytril Otic®):fluocinolone (SynOtic®) 1:1 - instill 0.25-1.0cc BID for 30 days until cytologic evidence of population normalization iii) Systemic terbinafine or keto/flu/itraconazole IF Malassezia otitis media/interna is identified and/or if generalized signs of Malassezia dermatitis are present. The "severe" yeast AND bacterial otitis externa 1) Address underlying etiology 2) Calm the ear canal i) topical and/or (immunosuppressive) systemic steroids or cyclosporine ­ extremely important!!! 3) Increase cell wall permeability to antimicrobials and address yeast Tris-EDTA PLUS ketoconazole (T8 Solution®, Triz-EDTA®) i) Tris = Surfactant product peptidoglycan membrane & binding destructive elastase enzyme - maintains pH of 8.0, optimum for function of the aminoglycosides and fluoroquinolones ii) EDTA = Ca/Mg binding agent decreased membrane integrity at porins influx of antibiotic iii) Ketoconazole to address the yeast infection iv) Cleanse ears BID, let stand 15 minutes before adding medications 4) Follow with topical antimicrobial treatment (100-1000X systemically delivered concentrations) i) Steroid (Synotic®, dexamethasone): enrofloxacin (Baytril® injectable 50 mg/ml): Enilconazole (Imaverol®) or miconazole (Confite®) (24cc:6cc:30cc) - instill 0.25-1.0cc BID OR ii) Steroid (Synotic®, dexamethasone): enrofloxacin/silversulfadiazene (Baytril Otic®) (1:1) - instill 0.25-1.0cc BID until negative cytology +/- negative culture depending on chronicity of the otitis. iii) Systemic antibiotics (based on culture and sensitivity findings) IF signs of otitis media are present and/or systemic terbinafine or keto/flu/itraconazole IF Malassezia otitis media/interna is identified and/or if generalized signs of Malassezia dermatitis are present.

CONCLUSION

Successful treatment of recurrent otitis externa can be challenging, but with proper diagnostics and a three-pronged approach to each case, the need for repeated medication use and/or surgery can be circumvented.

REFERENCES

Cole L et al. Plasma and ear tissue concentrations of enrofloxacin and its metabolite ciprofloxacin in dogs with chronic end stage otitis externa, 20th Proceedings of North American Veterinary Dermatology Forum 2005: 182 Cole L et al. Ciprofloxacin as a representative of disk diffusion in vitro susceptibility of enrofloxacin for bacterial organisms from the middle-ear tissue of dogs with end-stage otitis externa. Vet Dermatology 2006; 17(2): 128-133 Defalque VE et al. Aerobic and anaerobic microflora of the middle ear cavity in normal dogs. 20th Proceedings North American Veterinary Dermatology Forum 2005: 159 Gotthelf LN. Evaluation of the in vitro effect of Tris-EDTA on the minimum inhibitory concentration of enrofloxacin against ciprofloxacin resistant Pseudomonas Aeruginosa. Proc 19th Annual Congress of ESVD-ECVD 2003: 145 Graham-Mize CA & Rosser EJ. Comparison of microbial isolates and susceptibility patterns from the external ear canal of dogs with otitis externa. Journal of the American Animal Hospital Association 2004; 40: 102­108

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Green C. E. ed. Infectious Diseases of the Dog and Cat, 1st Edn. Philadelphia: WB Saunders, 1990: 98, 193 Griffin CE. Otitis Diagnosis, Methods for Determining Secondary Infections, 16th Proceedings of the American Academy of Veterinary Dermatology / American College of Veterinary Dermatology Meeting. Norfolk, 2001 Hall JA. Oral cyclosporine in the treatment of end state ear disease: A pilot study. Proceedings of the 18th Annual Meeting of the American Academy of Veterinary Dermatology and American College of Veterinary Dermatology. Monterey, California 2003: 217. Kowalski JJ. The microbial environment of the ear canal in health and in disease. Veterinary Clinical of North America: Small Animal Practice 1988; 18: 743 May et al. Isolation of Staphylococcus schleiferi from healthy dogs and dogs with otitis, pyoderma, or both. JAMVA 2005; 227(6):928-31 Noxon JO. Managing difficult ear infections. Supplement Compendium Continuing Education for Veterinarians 2008; 30 (1A): 21-28 Pankuch GA, Lin G, Hoellman DB, Good CE, Jacobs MR, and Appelbaum PC. Activity of Retapamulin against Streptococcus pyogenes and Staphylococcus aureus Evaluated by Agar Dilution, Microdilution, E-Test, and Disk Diffusion Methodologies. Antimicrobial Agents and Chemotherapy 2006; 50(5): 1727­1730

st Schick A et al. Effect of laboratory selection on otic culture results in dogs with bacteria otitis. 21 Proceedings of North American Dermatology Forum 2006: 134

Schick A et al. Variability of laboratory identification and antibiotic susceptibility reporting of Pseudomonas spp. isolates from dogs with chronic otitis externa. Veterinary Dermatology 2007; 18(2): 120-126 Scott DW., Miller WH., and Griffin CE. Diseases of Eyelids, Claws, Anal Sacs and Ears. In Muller & Kirk's Small Animal th Dermatology, 6 Edn. Philadelphia: WB Saunders, 2001: 1204-1235 Swinney A, Fazakerley J, et al. Comparative in vitro antimicrobial efficacy of commercial ear cleaners. Veterinary Dermatology 2008; 19:373-379. Traczewski MM & Brown SD. Proposed MIC and Disk Diffusion Microbiological Cutoffs and Spectrum of Activity of Retapamulin, a Novel Topical Antimicrobial Agent. Antimicrobial Agents and Chemo 2008; 52(11): 3863-3867 Trott DJ, Moss SM, See AM & Rees R Evaluation of disc diffusion and MIC testing for determining susceptibility of Pseudomonas aeruginosa isolates to topical enrofloxacin/silver sulfadiazine. Australian Veterinary Journal 2007; 85(11): 464-466 Wildermuth BE, Griffin CE, Rosenkrantz WS, Boord MJ. Susceptibility of Pseudomonas isolates from the ears and skin of dogs to enrofloxacin, marbofloxacin, and ciprofloxacin. Journal of the American Animal Hospital Association 2007;43(6):337-41

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COMPANION ANIMAL: Dermatology

DERMATOLOGIC PEARLS IN VETERINARY MEDICINE: UPDATE ON PRACTICAL CLINICAL TIPS

Anthony Yu, DVM, MS, DACVD

Associate Professor, Dermatology University of Guelph, Ontario Veterinary College Guelph, ON, Canada

PRACTICE TIP 1

Treatment alternatives for Canine Oral Papillomavirus Canine Oral Papilloma Virus (COPV) primarily affect young dogs and is characterized by the presence of multiple warts involving the oral mucous membranes, lips, occasionally esophagus, conjunctival mucous membranes and adjacent haired skin. Severe lesions can interference with mastication and swallowing. Current treatment options other than benign neglect include: 1) Surgical removal and CO2 laser ablation of the viral papillomas often results in recurrence and can even stimulate further growth, especially when removal occurs during the early growing stages. Most surgeons believe that removal when the papillomas are nearing their maximum size or when regressing provides the best success. 2) Papilloma Virus Vaccines including autologous and fractional (Georgetown University) may result in stimulation of the local immune defense system and result in regression of the papillomas. Use of the Human Papilloma Virus vaccine (Gardasil) in veterinary medicine hoping for cross immunization has been tried by the author with minimal success and substantial cost. Unfortunately, the potential for cure is counterbalanced by the possibility of inducing more viral growth and/or squamous cell carcinoma at the injection site. 3) Imiquimod (Aldara®) is classified as an immune response modifier that activates toll-like receptors and upregulates Il-6, TNF-alpha, and IFN-alpha secretion. The stimulation of the local immune defense system along with activation of Langerhans cells imparts an anti-proliferative and anti-viral effect to Aldara®. The product has been used with success to address equine sarcoids and viral aural plaques. Unfortunately, the packages are only distributed in 0.25gm packages and cost $15-20/packet...not an inexpensive venture. 4) Immunotherapy using Propionibacterium acnes to stimulate the T-helper 1 response or cimetidine to reverse Tsuppressor-mediated immune suppression, both activating the cell-mediated immune response have been tried with variable response. 5) Azithromycin at 10 mg/kg, q24h, for 10 days studied in a Randomized Double-Blinded Placebo Controlled study to induce clinical remission within 10-15 days in 10/10 of the treated versus 1/7 of the placebo group. Based on this study, we have been trying azathioprine in other viral papilloma-associated disorders with positive outcomes, however our numbers are too small to provide any definitive recommendations. It was postulated that Azithromycin may have anti-viral and/or immunomodulatory (IL-10 antagonist) effect. Yaci BB et al. Azithromycin therapy of papillomatosis in dogs: a prospective, randomized, double-blinded, placebocontrolled clinical trial, Vet Derm 2008;19:194-198.

PRACTICE TIP 2

Intralesional triamcinolone for hyperplastic/calcified ear canals This technique is presented as a "salvage" procedure for owners of pets that have hyperplastic, stenotic and even calcified ear canals. This option should be considered prior to a total ear canal ablation and bulla osteotomy (TECA-BO) as it offers a cost effective means of potentially reducing the inflammation, dissolving the calcium and opening up the ear canals, hence avoiding a TECA-BO. Triamcinolone is the corticosteroid of choice as it not only has anti-chemotactic activity to help calm the inflammatory response, but it also carries antifibroblastic properties, making it ideal for these chronic stenotic ear canals. I generally

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perform the procedure using heavy sedation (e.g. dexmedetomidine and butorphanol) with some degree of "bruticaine" depending on the patient's sensitivity; rarely is general anesthesia a requirement. Ear cytology is pursued prior to a thorough ear cleansing to provide topical post-injection therapeutic recommendations. A total of 6 to 10 mg per ear of triamcinolone loaded in a Luer-Locked or swedged-on needle syringe is injected in 0.1-0.3cc increments in a ring block formation. This is where I deviate from Craig Griffin, in that I start from the outside and move inward on repeated visits whereas Craig (tries to) insert a cone past the stenotic canal and injects the triamcinolone through a cone working his way from the inside outward. I personally feel that it is sometimes difficult to even find an opening, let alone passing an ear cone through the hyperplastic tissue, which would certainly be more painful requiring general anesthesia and adding additional risk to the patient and additional cost for the client. The injections are continued every 2 weeks for 3 treatments. In the meantime, underlying etiologies (Cutaneous Adverse Food Reactions, environmental allergies, hypothyroidism, etc.) are being addressed, along with providing topical and systemic anti-inflammatory and antimicrobial therapy based on your patient's clinical severity and ear cytology findings, respectively. Favorable responses should be noted by 6-8 weeks; if not, the option of a TECA-BO should be revisited. Griffin CE. Otitis Techniques to Improve Practice. Clinical Techniques in Small Animal Practice 2006;21(3):96-105.

PRACTICE TIP 3

An alternative approach to allergy testing Intradermal allergy testing (IDT) has been used for decades in veterinary dermatology to evaluate the local immune response to injected diluted environmental antigens for the purpose of providing information to help pet owners with allergen avoidance techniques, and, also as an aid for veterinarians/ dermatologists in the selection of antigens for inclusion into an allergen specific immunotherapy (ASIT). Serum allergy testing (SAT) is a more readily available method of evaluating for circulating allergen-associated immunoglobulins (IgE). Immunotherapy based on combined IDT and SAT have resulted in notable improvements/success rates. Personally, I have been able to achieve 75-90%+ resolution of allergic symptoms in my patients over the last 12 years since starting combined testing, whereas ASIT based on SAT yielded a 40-60% and ASIT based on IDT provided 60-80% relief. As the commitment to ASIT is often ONE year or greater, it behooves the clinician/dermatologist to include as much information as possible from their historical, IDT and SAT so that we can more appropriately select allergens for inclusion in the ASIT and tailor the solution to meet the patient's needs. As IDT is best performed 60-90 days after the allergy season to avoid seasonal anergy (e.g. fall for pollen allergic patients; spring for indoor/mold allergies sufferers), and, SAT is optimally pursued in the peak of the allergy season then I propose that: referring veterinarians submit serum for SAT in the peak of the patient's allergies when they typically present (contact your local dermatologist for their preferred lab and panel), and schedule an IDT 60-90 days after the patient's (peak) allergy season. I hypothesize that doing both tests at the appropriate times will result in a more representative allergen profile and hence improve the responses to ASIT. As well, by dividing up the testing, clients may be more amenable to pursuing both testing techniques and it also helps provide income and a vested interest for the referring veterinarian...a win-win-win scenario for client, referring veterinarian and veterinary dermatologist. Of course, follow-up and client education are also paramount to the success of immunotherapy.

PRACTICE TIP 4

How to get your pruritic patient to the test date without using steroids. Typically when performing either intradermal and/or serologic allergy testing, withdrawal from anti-inflammatory medications is recommended to avoid false negative reactions. My "ideal" withdrawal times as listed below: (Please contact your local veterinary dermatologist for their guidelines) Antihistamine: 10-14 days or longer (IDT only) Glucocorticoids: 2 wks topical; 4 wks oral; 12 wks injectable (IDT, SAT) Omega 3/6 fatty acids: 14 days (IDT only) Acepromazine: 5 days (IDT only) Aspirin: 48 hours (IDT only)

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Typically, we have managed to help our patients through this withdrawal by addressing secondary infections with antibiotics and/or anti-yeast medications, frequent topical cool water shampooing and barrier tools (e.g. T-shirts, E-collars, socks, etc.). Recently, a report looking at IDT before and after a 30-day course of cyclosporine yielded no significant evidence of suppression of the reactions. However, one should note that these study patients were cyclosporine naïve individuals and the allergy test panel was limited. With these caveats in mind, I still recommend at least a 14-day withdrawal off cyclosporine for patients that are receiving cyclosporine on a regular basis. But for those naïve patients, cyclosporine offers an alternative approach to get them to the allergy test date. Goldman C. Investigation on the effects of cyclosporine (Atopica) on intradermal test reactivity in atopic dogs. 24th Proceeding of the North Am Vet Derm Forum 2009 (April):207.

PRACTICE TIP 5,6,7,8,9,10,11,12,13

Predisposing, perpetuating and primary factors ­ an integrated approach to treating atopic patients Allergies, no matter how mild or severe, tend to be a lifelong condition as long as environmental influences remain the same. An integrated approach to treat allergic patients is therefore necessary to achieve longterm control. Targets of therapy include the following: 1) Primary causes: fleas, food antigens, environmental antigens, drugs 2) Predisposing causes: epidermal barrier defect, environment, genetics, vaccination 3) Perpetuating causes: bacteria, yeast Novel armaments have recently entered the veterinary market that helps us minimize various aspects in the PPP factors to drop our patients below their allergic threshold. 1) Primary Target a. Flea control - Comfortis® (Elanco Animal Health) is a new addition to our once-a-month flea control strategy to help eliminate adult fleas, ideally suited for the patient that is being bathed frequently like our atopic individuals. Unfortunately, because of the pork and soy-based beef flavoring, I would reserve the use of this product until AFTER your dietary trial(s) are completed. Vomiting is noted in up to 12% of patients and this product should not be used in epileptics or in conjunction with extra-label high dose ivermectin. Robertson-Plouch C, Baker KA, Hozak RR, et al. Clinical field study of the safety and efficacy of spinosad chewable tablets for controlling fleas on dogs, Vet. Ther. 2008;9:26­36 b. Non-steroidal alternatives for treatment of atopic dermatitis i. Cetirizine is a second-generation member of the piperazine family and active metabolite of hydroxyzine with mild sedative effects. In Canada it is called Reactine®, and in the USA it is known as Zyrtec®. Cetirizine onset of action is 1-3 hours following oral administration with peak concentrations achieved at 10 hours and duration of action ranging between 12-24 hours. Cetirizine is excreted largely unchanged in urine. A minimum of 2 weeks of continuous dosing is necessary to fully assess any antihistamine. Based on pharmacokinetic studies, the appropriate dose is 0.5-1.0 mg/kg Q12-24hrs. Side effects are no different than those noted for most antihistamines. This is my new favorite antihistamine as it also decreases influx of eosinophils into skin, which is great for treatment of eosinophilic granuloma complex patients and allergies. Papich MG et al. Pharmacokinetics of cetirizine in healthy cats. AJVR 2008;69(5): 670-674 Bizikova P et al. Hydroxyzine and cetirizine pharmacokinetics and pharmacodynamics after oral and intravenous administration of hydroxyzine to healthy dogs. Vet Derm 2008;19(6):348 - 357 ii. Masitinib mesilate is a potent and selective tyrosine kinase inhibitor of the c-KIT receptor. As the SCF/c-KIT pathway and pathogenesis of canine atopic dermatitis are intertwined, masitinib may be a suitable non-steroidal anti-inflammatory alternative to steroid use. An uncontrolled pilot study of 11 dogs dosed at 11 mg/kg/day for 28 days resulted in a reduction of clinical signs

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(mCADESI score) of 20.9% to 79.8% and with a decrease in pruritus. No severe adverse events occurred although 6/11 dogs presented with mild to moderate gastrointestinal disturbances. Daigle J, Moussy A, Mansfield CD, Hermine O. Masitinib for the treatment of canine atopic dermatitis: a pilot study. Veterinary Research Communications 2010;34(1):51-63 c. Dust mite control - Ecology Works® DustMite and Flea Control (Disodium Octaborate Tetrahydrate) or Bisell Acarosan® (Benzyl Benzoate) are available for use within the house on furniture and carpeting. Both act as desiccants and have a duration of activity between 4-8 weeks in high traffic areas to as long as 4-6 months in more secluded sites. The products are clear and odorless with a neutral pH, and will not stain lightly colored fabrics. Codina R, Lockey RF, Diwadkar R, et al. Disodium octaborate tetrahydrate (DOT) application and vacuum cleaning, a combined strategy to control house dust mites Allergy 2003;58:318­324 Swinnen C, Vroom M. The clinical effect of environmental control of house dust mites in 60 house dust mite-sensitive dogs. Vet Dermatol 2004;15(1):31-36 2) Predisposing factors a. Epidermal barrier (topical)- Allerderm SpotOn is a topically applied nano-emulsion of the Skin Lipid Complex comprised of biomimetic lipids such as ceramides + fatty acids + cholesterol, all components of the lamellar bodies in the stratum corneum. The product helps to normalize transepidermal waterloss (TEWL) and re-establish the barrier hence decreasing scaling, allergen exposure, secondary infections and irritant reactions. A. Piekutowska A, Pin D, Rème CA, et al. Effects of a Topically Applied Preparation of Epidermal Lipids on the Stratum Corneum Barrier of Atopic Dogs J Comparative Path. 2008;138(4):197-203 b. Epidermal barrier (dietary) - Pantothenic acid, Inositol, Nicotinamide, Choline, Histidine or PINCH are all component of the Skin Support® (Royal Canin). Above and beyond omega 3/6 fatty acids, the PINCH cocktail provides essential building blocks to help re-establish the epidermal barrier. Watson AL, Fray TR, Bailey J., et al. Dietary constituents are able to play a beneficial role in canine epidermal barrier function. Experimental Dermatology 2005;15(1):74 - 81 3) Perpetuating factors a. Bacteria release exotoxins (e.g. Staph enterotoxin A/B), which induce cytokine release and inflammation, act as superantigens that induce steroid resistance and stimulate hypersensitivity reactions by increasing IL4 and subsequently IgE production to environmental antigens including bacteria themselves. Enzymes such as proteases, ceramidases help to degrade the epidermal barrier and compromise the local defense system. With the growing concern regarding methicillin resistant bacteria, we have revisited the use of Staphage Lysate® (Delmont Labs), a Staphylococcus aureus phage lysate that stimulates IL-2 and interferon gamma production shifting the immune system toward a T-helper 1 response. Pulse antibiotic therapy is left as a last resort and reserved for the mature patient. DeBoer DJ, Moriello KA, Thomas CB, Schultz KT. Evaluation of a commercial staphylococcal bacterin for management of idiopathic recurrent superficial pyoderma in dogs. Am J Vet Res 1990; 51(4): 636-639 Kropinski AM. Phage Therapy ­ Everything Old is New Again. Can J Infect Dis Med Microbiol. 2006;17(5):297­306 b. Malassezia also releases fungal exotoxins (e.g. Zymogens), which activate complement cascade and induce inflammation. Like bacteria, Malassezia can act as a superantigen increasing patient hypersensitivity reactions including to the yeast themselves. Enzymes such as phospholipases and

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lipoxygenases can degrade the epidermal barrier lipids along with stimulate production of inflammatory leukotrienes and prostaglandins exacerbating an allergic response. We are currently incorporating Malassezia antigens (Greer Labs) into our immunotherapy treatment sets based on a multi-center study finding that demonstrated improvement in immunotherapy response and decreased need for anti-yeast therapy. For those not currently on immunotherapy, I use pulse anti-yeast therapy. Yu A, Morris D, Center D, Sauber L. hypersensitive dogs. Unpublished. Effect of Malassezia-specific immunotherapy in Malassezia

The 6th edition of Small Animal Dermatology was published in 2001, with typical production start dates of 3 years in advance, makes this textbook dated in today's exponentially expanding research in veterinary dermatology. It behooves us all to stay abreast of the current findings and opinions so that we can offer our clients the best treatment alternatives for their pets.

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COMPANION ANIMAL: Dermatology

KILLING BAD THINGS: FUNGI

Gregory C. Griffeth, DVM, DACVD

Staff Dermatologist ­ Matthew J. Ryan Veterinary Hospital University of Pennsylvania, School of Veterinary Medicine Philadelphia, PA

Although there are several dozen fungal species which affect the skin of our patients, there are only two which can be considered common. Malassezia pachydermatis is a very common secondary invader in patients with allergies and seborrheic disorders. It can be very difficult to manage. Dogs make up the vast majority of these yeast dermatitis patients. Dermatophytosis is less common, but, because of its contagious and zoonotic nature, it can be a major problem when it occurs. Almost any species can harbor dermatophytes, but it is most commonly seen clinically in cats. Fungal infections are often a significant challenge to treat. Before about 1980, there were few antifungal drugs, and they bore significant risk of dangerous side effects. In contrast, antibacterial drugs were and are typically (but not universally) very safe. Bacteria are very, very different from the vertebrates we commonly treat. Because of this, it is (now) fairly easy to target part of a bacterium's metabolism without significantly affecting its vertebrate host. Fungi, however, are eukaryotes. While there are indeed significant differences which we can and do exploit, fungi have nuclei, cell membranes, and enzymes which are quite similar to those of our patients. Because of this, antifungal drugs commonly have significant effects on the metabolic function of the host. This basic fact accounts for many of the problems that crop up in our attempts to resolve clinical fungal infections. Adverse effects on the patient and interactions with other drugs are often as important as the medication's efficacy when you are deciding on a course of therapy. Two major components of fungal cells are basically absent in our patients and are, therefore, candidates for targeting by antifungal drugs. The first is chitin, a carbohydrate which is also the most significant structural element in the exoskeleton of arthropods. While drugs that inhibit chitin synthesis were expected to be helpful in treating fungal infections, this hoped-for usefulness has not been borne out in clinical use. The second is ergosterol. This steroid performs much of the same function in fungal cell membranes that cholesterol does in ours: it controls the fluidity, and therefore the structural integrity, of the membrane. Too much or too little, and the membrane can not keep the inside in and the outside out. The majority of effective antifungal drugs target the synthesis or function of ergosterol in some way. Fungi are hard to kill without injuring the patient. Antifungals have many drug interations. Consideration of adverse effects and drug interactions is essential before initiating any systemic antifungal therapy.

USING MODERN ANTIFUNGAL MEDICATIONS

SYSTEMIC ANTIFUNGAL DRUGS: Imidazole and triazole antifungals are the mainstay systemic therapy for yeast and dermatophytes in veterinary medicine. Their mechanism of action is inhibition of (lano)sterol 14 alpha-demethylase , a CYP450 enzyme fungi use in synthesizing ergosterol required for cell membrane structure and function. There is some resistance to this activity reported in certain fungi, often via production of excess enzyme; this is a rare problem in veterinary medicine. As you likely know, CYP450 enzymes are extremely common: CYP enzymes have been identified from mammals, birds, fish, insects, worms, sea squirts, sea urchins, plants, fungi, slime molds, bacteria and archaea. (Thanks wikipedia!) The various imidazoles each exhibit different affinity for the CYP450 enzymes in these diverse systems. Efficacy is dependent on high affinity for fungal enzyme. Safety is dependent on low affinity for the patient's enzyme(s). CYP3A4 is the most important metabolic enzyme acting on xenobiotics in mammals. The vast majority of this enzyme is found in the liver; presumably, this is a major reason that hepatotoxicity is a common side effect of azole use. Of course, non-CYP-mediated toxicity may be a problem as well. And, since CYP enzymes are present at and necessary for all stages of prenatal life, azoles are contraindicated during pregnancy.

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Ketoconazole was the first commonly used azole antifungal. Its production and use increased greatly during the early AIDS epidemic. Its absorption from the gut can be problematic, however, and is inhibited by high gastric pH. Once absorbed, it is highly protein bound; because of this, KCZ has poor penetration of the CSF, prostate, testis, and any other tissue protected by a P-glycoprotein barrier. Being poorly water-soluble, it is delivered to the epidermis (in very useful quantities, actually) via sebaceous secretions. Ketoconazole is extensively metabolized by the liver, and is one of the strongest inhibitors of CYP3A4 known. It has been used safely for many years, but monitoring of liver enzymes and for signs of toxicity is required, especially with use over 30 days. This inhibition also causes interactions with many, many other drugs....mostly decreasing the metabolism/increasing concentration or duration. This may be used to advantage by inhibiting the clearance of expensive drugs, allowing better activity or lower cost. Finally, ketoconazole does interfere significantly with other steroidassociated enzymes, effectively stopping the production of many glucocorticoids and sex hormones while present. These effects must be considered, as humans have suffered severe Addisonian crises because of high ketoconazole dosing. Although doses are published, its use should be avoided in cats unless no safer options are available. Itraconazole is a newer triazole antifungal. It is commonly used in cats. It is quite expensive. Unfortunately, even more so than ketoconazole, absorption from the gut is not very good. The solid form of the drug (capsules) is best given with a fatty meal, as it is lipophilic and better absorbed in an acidic milieu. The compounded form is much less effective, possibly due to particle size and/or other manufacturing differences. I strongly recommend avoiding compounded itraconazole. The liquid form of the drug (Sporanox Oral Solution) is somewhat different...the drug molecules are held in solution by helper molecules called cyclodextrins. Because of this, bioavailability is much greater. However, this form should be given on an empty stomach, as the cyclodextrins can fail in overly acidic or fatty environs. Itraconazole is highly keratinophilic ­ it concentrates in the stratum corneum, hair, and nails. This is one reason for its excellent efficacy against dermatophytes...which preferentially consume keratinaceous material. It also allows pulse dosing, since once steady state levels of drug are present in these structures, they typically remain until physically sloughed, even without further administration. Like ketoconazole, it is protein-bound, limiting its distribution to CNS and other barriered sites. Adverse effects like hepatotoxicity, nausea/vomiting, and vasculitis are reported. Monitoring of liver enzymes is recommended for the typical long dosing duration used for dermatophytosis (and many deep/systemic fungal infections.) Inhibition of mammalian CYP450 enzymes is less than with ketoconazole, and affinity for fungal enzymes is greater; therefore, safety and efficacy are both somewhat greater. Fluconazole is another triazole antifungal. Its use has grown exponentially in veterinary medicine since 2004 when the patent expired on the name-brand Diflucan. This reduced the cost of therapy by 80-90%. It is water-soluble, non-lipophilic, and is not protein bound, but is keratinophilic. Because of this it is readily absorbed without any byzantine biochemical or gustatory machinations. It also penetrates CNS, aqueous humor, and other challenging sites very well. Its affinity for fungal enzymes is orders of magnitude greater than that for mammalian ones; its safety profile is very, very good. The only drawback for fluconazole is it theoretical efficacy. Many in vitro studies show much higher MICs for FCZ than KCZ or ICZ. For Malassezia infections, there seems to be no clinical difference, however, and any possible delay in effectiveness is not terribly problematic. For dermatophytosis, and even more so for possibly life-threatening systemic infections, the safety and cost-effectiveness benefit might be outweighed by the presumed greater efficacy of itraconazole. This doesn't apply to CNS infections, in which fluconazole is the drug of choice because of its penetration. It also concentrates well in urine in active form. Voriconazole and posaconazole are two newer triazoles. They are very very expensive, and typically indicated only for unusual or resistant fungal infections. Since these are both rare and frequently misdiagnosed in veterinary medicine, their use should be limited to tertiary specialty practice for now. Allylamines and other squalene epoxidase inhibitors are the newest antifungals available to veterinarians. Instead of inhibiting 14Alpha-demethylase and aromatase which catalyze several reactions modifying preformed steroids, allylamines prevent the essential initial reaction, the one-step conversion of linear squalene into the polycyclic steroid lanosterol, the

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precursor to all fungal steroid molecules. The lack of ergosterol is certainly part of the lethal effect of allylamine, but the accumulation of excess squalene may be a part as well. Terbinafine is the prototypical drug of this class. Like fluconazole, its use has grown greatly since the inexpensive generic has become available. The most common current use is in cats for dermatophytosis, and, less often, sporotrichosis. It is less effective against yeast than the azoles. Terbinafine is also used topically; all other current SEIs (amorolfine, naftifine, butenafine) are topical-use-only drugs, and therefore are very rarely used on veterinary patients. Depending on the ultimate determination of safety and efficacy, oral terbinafine may become the drug of choice for dermatophytosis in cats. Older antifungals: Griseofulvin, amphotericin B, and iodides are still occasionally used for fungal infections of the skin or ears, but this use is rapidly waning. This is true across most of veterinary and human medicine in the face of the safer and more effective agents discussed above. Lufenuron is the only chitin synthase inhibitor in use. Because of the presence of chitin in the cell wall of pathogenic fungi, it was surmised that lufenuron might have significant antifungal activity, particularly against dermatophytes. It doesn't work. No significant antifungal effects have been repeatably demonstrated. Azoles are the mainstay of dermatological antifungal therapy. All are effective against Malassezia. Fluconazole is the safest systemic azole. Itraconazole is the most effective against dermatophytes. Terbenifine, and other allylamines, are also effective against dermatophytes, and may be used more commonly in the future. Griseofulvin is effective, but has significant drawbacks to use. Lufenuron is not a useful antifungal drug. Miconazole, ketoconazole, and clotrimazole are all effective topically.

TOPICAL ANTIFUNGAL AGENTS

The most common topical agents used for fungal infections are also imidazoles: Miconazole is the most commonly used topical antifungal in our clinic for both Malassezia and dermatophytes. It comes as a shampoo, as well as in many other formulations. It is not used systemically, and inadvertent consumption should be avoided. This seems to be the most potent topical-only azole. Clotrimazole is used similarly to miconazole. It is commonly found in "triple" combinations with an aminoglycoside for antibacterial effect and a potent topical steroid anti-inflammatory for use in otitic patients. Ketoconazole is used both topically and systemically, and is very effective for Malassezia; less so for dermotophytes. It, too, is frequently combined with antibacterials because of its narrowness of spectrum. OTHERS INCLUDE: Lime sulfur (calcium polysufide) is a very potent topical antifungal (it is also antibacterial, antipruritic, and very useful against sarcoptiform and other mites.) It is very safe, and is often used in unweaned or just-weaned kittens. What is the down side, you might ask? It smells terrible and stains everything yellow-orange -- except precious metals, which it turns black. Unless highly diluted, it is herbicidal. This is the topical of choice when maximal control of dermatophytes (in a shelter, e.g.) is required. It's fairly cheap, too, and can be used for environmental control. Because of its foul nature, it isn't often used for yeast infections, but would be expected to be effective. As with other agent, avoiding unintended oral consumption is important. Once patients are dry, grooming is harmless; they're also unlikely to stain other objects once dry. Chlorhexidine is a potent antimicrobial bisguanide. Its activity is focused on the cell membrane, and it has fairly broadspectrum activity. It is specifically very potent against Gram positive organisms like staphylococci, with significant activity against Gram negatives, fungi, and many viruses. Its overall reactivity is much less than benzoyl peroxide, but many soaps and some other anionic chemicals can reduce its effectiveness. Unless formulated with harsher agents, chlorhexidine is relatively mild; any drying or irritation is likely from the detergent or other agents in the formulation.

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Maximum efficacy is seen with the 4% concentration...especially for fungi and other tough organisms. Unlike benzoyl peroxide, it can sometimes be combined with other antimicrobials without harmful interaction ... antifungal azoles are frequently used in this role. Together, as in KetoChlor for example, these provide very potent, very broad-spectrum antimicrobial effect. Other than its gentleness and good efficacy, duration of activity is a major benefit of using this chemical. With repeated use, antimicrobial effect for outlasts the presence of the chlorhexidine-containing product. Benzoyl peroxide is a highly reactive molecule. Because of this, it rapidly induces lethal chemical injury to microbes. It has a very broad spectrum because of this activity as well, and readily kills most , fungi as well as most bacteria, viruses, and other microbes. Its chemical activity also breaks down the intercellular junctions in the stratum corneum and solubilizes many of the lipids of the skin; this moderate keratolytic effect is very useful in patients with hyperkeratosis, comedones, and other disorders characterized by excess production of sebum, apocrine sweat, and keratinocytes. It bleaches hair (good in a Maltese, not so good in Black Labradors, who can end up orangeish) and oxidizes the sulfhydryl moieties that make skunks so stinky. This aggressive chemical activity can be very drying and irritating, so some consideration of the overall skin condition of the patient is important. Because of the nature of the stable shampoos manufactured, sudsing is paltry at times; warning owners in advance helps stave off complaints. Owners are best warned that benzoyl peroxide is a moderately potent bleach, and can damage colored textiles. Therapeutically, the major drawbacks are irritation of the skin and a relatively short duration of effect. Iodine is a potent older agent. Much like benzoyl peroxide, its activity is due to its highly reactive nature. It does not possess the bleaching or keratolytic activity of benzoyl peroxide, or the inertness of chlorhexidine. It is fairly inexpensive, though, and very broad-spectrum. With significant contact time, only spore-forming bacteria and protozoa are resistant. It does have some persistence on skin, depending on formulation. Iodine can be highly irritating, which hampers its clinical use. Iodophors reduce this problem by combining the I2 with a polymer, but this reduces persistence as well. Currently, iodine use is limited to horses in most cases. It is contraindicated in cats because of their grooming behavior. Silver sulfadiazine is a broad spectrum antimicrobial agent that is frequently used topically. Typical formulation is as a pearlescent cream containing SSD at 1% concentration. Silver ions and sulfadiazine are very active antibacterials, but have only moderate anti-yeast activity. It promotes re-epithelialization of wounds, and is soothing upon application. As a cream formulation it is limited to focal or at most regional use. Occasionally it is useful as monotherapy in patients for whom mild yeast numbers are concurrent with significant bacterial disease.

THE TWO MAJOR SUPERFICIAL FUNGAL DERMATOSES

MALASSEZIA Malassezia dermatitis, otitis, and paronychia rival Staphylococcal infections as the most common presenting problem in my patients. This organism is not contagious, per se. It is a fairly simple monomorphic budding yeast, and at least one species is present in some, usually small, number on the skin and/or ears of most mammals. It can cause life-threatening infections of premature babies; systemic infections are otherwise vanishingly rare. In the presence of an underlying predisposing problem, the normally small numbers present on the skin can grow wildly out of control. This causes inflammation. Unfortunately, Malassezia are particularly adept at using sebaceous and apocrine secretions as a food source....so increased secretion because of inflammation makes the problem worse, not better. To a certain extent, this problem is mediated by a hypersensitivity reaction to the yeast themselves. This, and the extent of atopy, endocrinopathy, or other predisposing disease, determine the chronicity and severity of the infections. It is uncommon for a veterinary patient to have a onetime-only yeast infection. Malassezia dermatitis, otitis, and paronychia are difficult to diagnose with the naked eye, but simple via impression or tape cytology. This is also the best way to evaluate the effectiveness of therapy Topical therapy is the first line in treating Malassezia. This is especially true of otitis. Ear infections are very difficult to resolve without consistent, frequent topical treatment. Miconazole, clotrimazole, and ketoconazole are the agents most commonly found in veterinary topicals; they are uniformly effective against this yeast. When used properly, with a 10 minutes lather-soak time before rinsing, shampoos have significant residual effect. I use them twice weekly to every other

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day. Other preparations with antifungal azoles like wipes, sprays, or flushes are very helpful, especially in areas with focally severe infection like the feet or chin. Twice daily use of these agents is best. Malassezia otitis should be treated with a topical azole and steroid combination, again twice daily until a week after resolution. Systemic therapy for Malassezia is often necessary. Patients with severe or recurrent infections, patients who are difficult to treat topically, and all patients with yeast paronychia can benefit from oral antifungals. My drug of choice is fluconazole, 5mg/kg po qd for 30 days. Side effects are very rare, and the resistance is not seen. Ketoconazole is also uniformly effective at 10 mg/kg qd for 30 days. Both should be given with food, although this is more important for the poorlysoluble ketoconazole. Serum liver enzymes should be measured for any patient receiving an antifungal azole for extended periods; again, because of known hepatotoxicity, this should be done earlier and more often when ketoconazole is used. Malassezia infections are common. They are not contagious, but caused by underlying factors. Topical azoles are very effective. If systemic drugs are indicated, use fluconazole. Other azoles are effective, but have greater side effects or are significantly more expensive. Addressing the underlying problem is essential in managing chronic recurrence.

DERMATOPHYTES Dermatophytosis is relatively uncommon in the well-kept adult patients I typically see, but is a significant differential in the diagnosis of the majority of dermatoses. Dermatophytes are spore-forming hyphal fungi that live on keratin. Different species have evolved preferences for soil, animals, or humans. The ones that infect our patients, particularly, have a few characteristics that make them a significant concern. They are contagious and zoonotic, which makes public health considerations important. They are also unusually persistent in the environment. This means that simply treating clinically apparent disease is rarely enough to control an outbreak, especially in cats. It should also be noted that, while the disease is usually relatively mild and limited to the stratum corneum and hair shaft, dermatophytes can cause significant and sometimes life-threatening deep infections in some patients. Diagnosis is best made by professional fungal culture. Dermatophyte identification is difficult, and is best performed by a trained microbiologist or mycologist. Furthermore, dermatophytes are Biosafety Level 2 pathogens, and require special handling facilities and techniques. Finally, "room temperature" can vary greatly without a dedicated incubator; this reduces efficiency and accuracy. I send plucked hairs and toothbrush cultures out. A Wood's lamp can be helpful in diagnosing some M. canis infections, but negative results are meaningless, since less than half of dermatophyte infections "glow." Topical treatment is necessary for all cases of dermatophytosis. It may be the only necessary treatment for dogs. It is probably the only affordable therapy for horses and other large animals. The most effective topical agent for treating dermatophytosis in the US is lime-sulfur dip. If it weren't malodorous and staining, that's all anyone would use. Enilconazole, where available, is equally effective. There are reports of success with the poultry-approved environmental version (Clinifarm) used off-label. However, that's very, very off label. Given the almost complete safety and efficacy of lime-sulfur, the risk doesn't seem worth any benefit. Miconazole shampoo is also useful, and much less odious. It is reportedly somewhat less effective; better is miconazole/chlorhexidine combination. I typically use lime sulfur or miconazole/chlorhexidine shampoo twice weekly for the duration of treatment. Compliance issues often reduce lime sulfur use to less often, but three good dips in the first ten days of treatment is essential. Full-body use of all topicals is essential, as spot-treatment alone is associated with chronic, subclinical infections which can continue to seed the environment with infective spores. Systemic therapy should be used in all cats with dermatophytosis, and any dogs which fail a good topical regimen after 3-4 weeks. The drug of choice for systemic treatment for cats and small dogs is itraconazole at 10mg/kg po qd. It is very effective, and much safer than the previous choice, griseofulvin. If at all possible, I prefer Sporanox liquid. The itraconazole in this form is solubilized with cyclodextrins, making it substantially more bioavailable than any other oral form. Because of this high-tech molecular engineering, Sporanox solution must be given on an empty stomach. The second choice is Sporanox capsules. Currently, there is no cost benefit to using the capsules. Generic and compounded itraconazole have been associated with some very expensive treatment failures and should be avoided. Because of the cost, low-dose treatment (2.5-3 mg/kg po qd) with more frequent cultures has been used effectively, as has been various forms of pulsed therapy. I would strongly consider these when multiple animals are affected in one location.

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Ketoconazole and fluconazole have both been used when itraconazole therapy is not an option. There is variable data on efficacy of these drugs. In the larger dogs for which Sporanox is prohibitively expensive, I choose fluconazole at 5-10mg/kg po qd, along with the intensive topical therapy. Systemic antifungal therapy should be continued until two negative fungal cultures are achieved, at least one week apart. Environmental treatment is essential if a permanent cure is to be obtained. In situations involving Persian-type cats, breeding facilities, shelters, multi-animal households, or experimental colonies, environmental cleanup is as important as drug therapy to long-term success. Several protocols have been published, but all involve the quarantine of affected animals, destruction of all bedding and other textiles which can reasonably be discarded, frequent vacuuming with a wellfiltered machine, laundering and heat-drying of any textiles retained, and the use of topical disinfectant on all hard surfaces. Vacuuming and disinfection often need to be performed daily for several weeks. A 0.5-0.6% solution of sodium hypochlorite (that is, one part household bleach to nine parts water) is usually recommended. Enilconazole can be used as well. Lime sulfur may be used, but its odor and tendency to stain usually preclude use. For households without the above risk factors, I usually recommend daily vacuuming for 7 days with disinfection of all surfaces and laundering of all bedding, etc, weekly. In any case, for environmental cleanup, more is better. All dermatophytosis should be treated with topical antifungals. Lime sulfur and enilconazole are best. Miconazole is also useful, especially in combination with chlorhexidine. Treat topically twice weekly. All cats should receive systemic therapy. Dogs with refractory disease should be treated systemically, too. Itraconazole, at 10mg/kg po qd is the drug of choice. Other dosing schedules have been effective. Fluconazole and ketoconazole are probably less effective, but may be used. Environmental cleaning and treatment are important parts of therapy.

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COMPANION ANIMAL: Immune-Mediated Diseases

IMHA & IMT

Mary Beth Callan, VMD, DACVIM

Associate Professor of Medicine ­ Matthew J. Ryan Veterinary Hospital University of Pennsylvania, School of Veterinary Medicine Philadelphia, PA

Immune-mediated hemolytic anemia (IMHA) and immune-mediated thrombocytopenia (IMT) are encountered commonly in small animal practice, with the frequency of both considerably higher in dogs than cats. These hematologic disorders may represent more of a therapeutic than diagnostic challenge. However, patients with a regenerative anemia in the absence of blood loss or severe thrombocytopenia may be misdiagnosed as having IMHA or IMT, respectively, when other differential diagnoses are not considered or evaluation is incomplete. This presentation will focus on the diagnostic approach to patients with anemia and/or thrombocytopenia, highlighting clinical cases that closely mimic IMHA or IMT. In addition, treatment options for patients with IMHA or IMT not responsive to or intolerant of corticosteroids will be discussed.

DEFINITION AND PATHOPHYSIOLOGY

IMHA and IMT are characterized by reduced survival times of red blood cells (RBCs) and platelets, respectively, due to premature removal of antibody-coated RBCs and platelets from the circulation. In IMHA, IgG-mediated hemolysis is primarily a result of extravascular destruction of RBCs by macrophages in the spleen and to a lesser extent the liver, whereas destruction of RBCs by IgM is mediated by complement activation, resulting in intravascular hemolysis. Platelet destruction in IMT is typically mediated by IgG. In primary or idiopathic IMHA and IMT (also referred to as autoimmune hemolytic anemia [AIHA] and idiopathic thrombocytopenic purpura [ITP], respectively), there is no identifiable cause for the production of anti-RBC and anti-platelet antibodies. In contrast, in secondary IMHA and IMT an underlying infectious agent, neoplasia, or a drug may act as a stimulus for the production of antibodies which bind to RBCs and platelets through a variety of mechanisms. Therefore, a diagnosis of primary IMHA or IMT is one of exclusion, made by ruling out all potential underlying causes. Rarely, IMHA and IMT occur simultaneously, a condition referred to as Evans' syndrome.

CLINICAL SIGNS

The most common clinical signs for both dogs and cats with IMHA at presentation include lethargy, decreased appetite, pallor, and weakness. Pigmenturia, icterus, and vomiting may also be noted. In patients with IMT, petechiae, ecchymoses, and mucosal surface bleeding (e.g., gingival bleeding, epistaxis, melena, hematuria) are frequently observed. Splenomegaly due to extramedullary hematopoiesis and lymphoid hyperplasia is not uncommon in patients with IMHA and IMT, and tachycardia, heart murmur, and poor pulse quality may be noted in patients with severe anemia due to hemolysis or blood loss. Fever is a variable feature of immune-mediated hematologic disorders.

DIAGNOSTIC EVALUATION

In addition to evidence of hemolytic anemia, the diagnostic criteria for IMHA include persistent RBC agglutination, a positive Coombs' test, and moderate to marked spherocytosis. For patients having a positive saline (or slide) agglutination test, the RBCs should be washed three times in saline to determine if the agglutination is persistent. Persistent RBC agglutination precludes the ability to perform blood typing using an agglutination assay, a blood crossmatch, and a Coombs' test. While a regenerative RBC response is expected in patients with hemolysis, it is not uncommon for some patients with IMHA to present with a nonregenerative anemia; the onset of anemia may be acute in onset (< 3-5 days), or there may be immune-targeting of RBC precursors in the bone marrow. The most notable finding on the initial laboratory evaluation of patients with IMT is severe thrombocytopenia, with a platelet count typically < 30,000/L and often < 10,000/L. Anemia may be noted if there has been considerable blood loss. Prothrombin time (PT) and activated partial thromboplastin time (aPTT) are usually normal. For patients with either IMHA or IMT, a complete medical history, physical examination, and diagnostic evaluation are necessary to identify any underlying disorders. In addition to the standard CBC (including a blood smear evaluation), serum chemistry screen, and urinalysis (as well as Coombs' test for suspected IMHA), imaging is helpful to identify neoplasia and

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some infectious diseases (thoracic radiographs and abdominal ultrasound) and ingestion of zinc foreign bodies (abdominal radiographs) that could cause intravascular hemolysis. Infectious disease screening may depend on geographic location and patient exposure. A SNAP 4Dx (Lyme, heartworm, Ehrlichia canis, and Anaplasma phagocytophilum) is frequently performed as an initial screen; however, it should be noted that dogs with confirmed Anaplasma phagocytophilum have tested negative on the initial SNAP 4Dx since illness may precede seroconversion. While Babesia is an intraerythrocytic organism, thrombocytopenia has been reported to be a more common hematologic abnormality than anemia in dogs with various Babesia sp. There is an extensive list of other infectious diseases (e.g., Leptospirosis, Rocky Mountain spotted fever, Leishmaniasis, Bartonellosis) potentially associated with immune-mediated hematologic disorders, so the extent of testing is dependent on the patient's overall condition. For cats with immune-mediated hematologic disorders, potential underlying infectious agents include FeLV, FIP, Mycoplasma hemofelis, and Bartonella. For a patient with evidence of hemolytic anemia that does not meet the diagnostic criteria for IMHA (i.e., lack of persistent RBC agglutination, positive Coombs' test, or moderate to marked spherocytosis), it is imperative to consider other differential diagnoses. Hereditary erythroenzymopathies, phosphofructokinase (PFK) deficiency and pyruvate kinase (PK) deficiency, should be considered in young dogs with highly regenerative anemia. PFK deficiency is characterized by intermittent intravascular hemolytic crises that may follow periods of hyperventilation, potentially in association with panting during excitement, excessive barking, high environmental temperatures, and rigorous exercise. PFK deficiency has been identified in English springer spaniels, cocker spaniels, Whippets, and a mixed breed dog. PK deficiency results in chronic ongoing hemolysis rather than intermittent hemolytic crises; affected dogs are usually presented with a moderate to severe but highly regenerative anemia and osteosclerosis. Breeds in which PK deficiency has been identified include the Basenji, Beagle, West Highland white terrier, Cairn terrier, Chihuahua, miniature Poodle, Pug, Dachshund, and toy American Eskimo dogs. PK deficiency has also been identified in Abyssinian, Somali, and DSH cats, although the clinical presentation differs from that of affected dogs, with chronic intermittent hemolytic anemia rather than ongoing hemolysis. DNA testing is available for diagnosis of PFK and PK deficiency through the Deubler Genetic Disease Testing Laboratory at PennVet.

TREATMENT

For patients with secondary IMHA or IMT, treatment of the underlying disease (e.g., doxycycline for Ehrlichiosis) or removal of the triggering agent (e.g, sulfonamide or cephalosporin) may be all that is necessary. For patients with primary IMHA or IMT, tapering doses of immunosuppressive drugs are typically administered for 4-6 months. Corticosteroids: The mainstay of treatment for both dogs and cats with primary IMHA or IMT is corticosteroids: prednisone (1-2 mg/kg PO BID) or dexamethasone (0.1-0.2 mg/kg IV BID). There are several potential mechanisms of action of corticosteroids in the treatment of immune-mediated hematologic disorders, including decreased removal of antibody-coated RBCs and platelets by reducing the number of Fc receptors on the macrophages responsible for clearance from the circulation, impaired RBCor platelet-antibody interaction, decreased production of anti-RBC or -platelet antibodies, and a suppressed inflammatory response. In addition to iatrogenic hyperadrenocorticism, potential adverse effects of corticosteroids include a predisposition to thromboembolic disease, development of insulin resistance, and rarely gastrointestinal ulceration. All immunosuppressive drugs will predispose patients to secondary infections, most commonly of the urinary tract and skin. For patients with primary IMHA or IMT that fail to respond to corticosteroids within 2 weeks or develop significant adverse reactions, a secondary immunosuppressive agent may be considered. However, it is important to recognize that there are limited published data documenting the efficacy of these medications in the treatment of primary hematological disorders. Vincristine (Oncovin): Vincristine is a vinca alkaloid that avidly binds to tubulin, a major component of platelet microtubules. For dogs with primary IMT, administration of a single dose of vincristine (0.02 mg/kg IV) in combination with corticosteroids has been shown to decrease the duration of severe thrombocytopenia (platelet count < 40,000/L) by 2 days (mean, 6.8 days with 1 prednisone alone vs 4.9 days with vincristine/prednisone); its effect on long term response has not been evaluated. The mechanism by which vincristine increases the platelet count in dogs with IMT (as well as normal dogs) is uncertain, but proposed mechanisms include impairment of the mononuclear phagocytic system, stimulation of transient megakaryocyte platelet release, and stimulation of thrombopoiesis through humoral factors. Vincristine does not appear to significantly impair platelet function. Potential adverse effects include perivascular sloughing (if drug extravasates during IV administration) and, rarely, myelosuppression.

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Human intravenous immunoglobulin: Human intravenous immunoglobulin (hIVIG), prepared from large pools of human plasma, is composed of highly purified IgG, with trace amounts of other immunoglobulins. It has been used in the treatment of canine IMHA and IMT, as well as severe dermatologic conditions due to drug reactions and pemphigus foliaceous in both dogs and cats. The proposed mechanisms of action in treatment of immune-mediated hematologic disorders include blockade of macrophage Fc receptors, resulting in decreased removal of antibody-coated RBCs and platelets from the circulation, interference with activation of B and T cells, and possibly anti-idiotypic down-regulation of autoantibody production. Results of 2 prospective, randomized, controlled clinical trials evaluating hIVIG in the treatment of canine primary IMHA and IMT have been recently published.2,3 In a study comparing administration of prednisone alone vs. prednisone and hIVIG (0.5 g/kg/day for 3 consecutive days) in the initial management of dogs with primary IMHA, there was no difference in response rate, survival, length of hospitalization, or transfusion requirement between groups.2 In a similar study comparing prednisone alone vs. prednisone and a single dose of hIVIG (0.5 g/kg) for the acute management of dogs with primary IMT, there was a significant reduction in platelet count recovery time (time to platelet count > 40,000/L) (mean, 7.5 days vs. 3.7 days) and duration of hospitalization (mean, 4 days vs. 8 days) for the hIVIG group.3 However, there was no difference in time to complete platelet count recovery (platelet count > 160,000/L) between treatment groups. Results of this study are similar to the prednisone/vincristine study mentioned above, and it is not clear whether single dose hIVIG offers any advantage over single dose vincristine (both in combination with prednisone) in shortening the duration of severe thrombocytopenia in dogs with primary IMT. Given that there is a considerable difference in cost between vincristine (dose 0.02 mg/kg for a 10 kg dog - < $7) and hIVIG (dose 0.5 g/kg for a 10 kg dog - $720), it may be difficult to rationalize the cost associated with administration of hIVIG to dogs with primary IMT. (Note: the recommended dose of hIVIG for treatment of immunemediated hematologic disorders in dogs ranges from 0.5 to 1 mg/kg administered once or on 2 consecutive days) Cyclosporine (Neoral, Atopica): Cyclosporine, a calcineurin inhibitor, blocks early T cell activation and prevents synthesis of several cytokines, particularly IL2. Without IL-2, further T cell proliferation is inhibited, and T cell cytotoxic activity is reduced. A typical starting dose is 3 mg/kg PO BID, with the dose adjusted based on clinical response and/or measurement of trough cyclosporine levels (target range varies depending on assay used). Cyclosporine has variable GI absorption, and it is metabolized by the liver via the cP450 system. Ketoconazole, which inhibits cP450, may be administered concurrently to increase blood cyclosporine concentration, though it adds to potential GI disturbance and may cause hepatotoxicity. Reported adverse effects of cyclosporine in dogs and cats include vomiting, diarrhea, gingival hyperplasia, and papillomatosis; in contrast to humans, nephrotoxicity and hepatotoxicity are uncommon adverse effects in dogs and cats. Immunosuppression in general is associated with an increased risk of developing neoplasia, and we have documented papillomavirus-induced squamous cell 4 carcinoma in a dog receiving prednisone and cyclosporine for 2 years. In addition, cyclosporine is diabetogenic, and the combination of corticosteroids and cyclosporine has resulted in diabetes mellitus in dogs and cats. Therefore, cyclosporine would not be the ideal second agent for treatment of primary IMHA or IMT in a dog or cat with pre-existing diabetes mellitus. There are no prospective controlled studies in veterinary medicine documenting the efficacy of cyclosporine in the treatment of primary IMHA or IMT; its use is based on anecdotal experience. Azathioprine (Imuran): Azathioprine is an antimetabolite, a purine analog that once incorporated into DNA results in RNA miscoding and faulty transcription (i.e., serves as a fraudulent nucleotide base during DNA/RNA synthesis). It also blocks de novo purine synthesis, thereby limiting lymphocyte proliferation by impairing the cell cycle. The use of azathioprine in cats is controversial (due to profound neutropenia), but the recommended dose for dogs is 1.65-2.2 mg/kg PO SID-EOD. The main adverse effects of azathioprine are myelosuppression and hepatotoxicity; pancreatitis has also been reported. Azathioprine is a common choice for a second agent in the management of canine IMHA and IMT, potentially due to the minor expense in comparison to other immunosuppressive agents. There are two recent retrospective studies of canine IMHA in which the 5,6 However, prospective controlled studies are combination of prednisone and azathioprine was standard therapy. necessary to determine the efficacy of this drug combination in the management of canine IMHA or IMT. Leflunomide (Arava): Leflunomide is an immunomodulating agent that has been proposed to be useful in the treatment of dogs with a variety of immune-mediated disorders, including IMHA and IMT.7 Leflunomide inhibits dihydroorotate dehydrogenase and, thereby, de novo pyrimidine synthesis, decreasing DNA and RNA synthesis and inhibiting T and B cell proliferation. The initial recommended dose for IMHA/IMT is 4 mg/kg PO SID, with dose adjusted to maintain trough blood levels of the active metabolite (A77 1726) at ~ 20 g/mL. Potential adverse effects include vomiting, lymphopenia, and anemia. There is very

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limited clinical information on the use of leflunomide in dogs, but with a generic formulation now available, the reduced cost may make this drug a more common choice as a second agent in dogs unresponsive to or intolerant of corticosteroids. There is a recent case report describing successful treatment of Evans' syndrome in a diabetic dog using a single dose of hIVIG and leflunomide (2 mg/kg PO BID), without the use of corticosteroids; a full clinical response was noted after 4 weeks of treatment, and the dog remained in complete remission over 19 months of follow-up (with 10 months of tapering leflunomide therapy).8 Mycophenolate mofetil (Cellcept): Mycophenolate inhibits inosine monophosphate dehydrogenase, an enzyme necessary for de novo purine synthesis. Since T and B cells are dependent on de novo synthesis of purines (while other cells can use salvage pathways), proliferative responses of T and B cells are inhibited and suppression of B cell formation of antibodies occurs. There are no published data documenting efficacy of mycophenolate in the treatment of primary canine IMHA or IMT, so its use is based on anecdotal experience (with a dosing range of 12-17 mg/kg PO SID or divided BID). Adverse effects reported in dogs include vomiting, diarrhea (with some dogs experiencing severe hemorrhagic diarrhea), anorexia, and lethargy. Cyclophosphamide (Cytoxan): Cyclophosphamide is an alkylating agent, resulting in alterations in DNA structure that can be lethal to the cell or produce miscoding errors that inhibit cell replication or DNA transcription. It suppresses both T-cell activity and antibody production. Potential adverse effects of cyclophosphamide include myelosuppression, GI distress, and hemorrhagic cystitis. In a randomized controlled prospective clinical trial evaluating whether combined cyclophosphamide and prednisone therapy was more efficacious than prednisone alone in the initial treatment of canine IMHA, there was no apparent beneficial effect from the addition of cyclophosphamide; in fact, reticulocytosis was suppressed during the first week of therapy in the dogs receiving combination therapy compared to 9 prednisone alone. We do not recommend use of cyclophosphamide for treatment of IMHA or IMT. Splenectomy Splenectomy is considered a treatment option in both human and veterinary medicine for immune-mediated hematologic disorders refractory to conventional therapy. The rationale behind splenectomy in such cases is to eliminate the major site for removal of antibody-coated RBCs or platelets from the circulation and, to a lesser extent, decrease antibody production. A recent retrospective case series evaluating splenectomy in 10 dogs with IMHA who had been administered immunosuppressive medications for a median of 4 days (range, 0-22 days) reported that 9 of 10 dogs survived to 30 days 10 post-splenectomy, with 4 of the 9 no longer on any immunosuppressive drugs. There were no relapses during the 30 days, but there was no follow-up beyond that time point. The authors concluded that use of splenectomy may be associated with an improved outcome in dogs with IMHA, but as indicated above for the various immunosuppressive drugs, prospective controlled studies would be needed to document efficacy of splenectomy in the management of primary IMHA and IMT in dogs and cats.

The prognosis for canine primary IMT is generally good, with a reported mortality rate of 10%.11 In contrast, the prognosis for canine primary IMHA is generally considered guarded to poor, with mortality rates ranging from 24-70%.2,5,6,9,12 On the other hand, the prognosis for feline primary IMHA appears more favorable, with a reported mortality rate of 24%.13 Thromboembolic disease due to hypercoagulability associated with IMHA and its treatment (i.e., corticosteroids) is an important complication contributing to the high mortality rate in dogs. A recent retrospective study evaluating thromboelastograms (TEGs) in dogs with IMHA documented hypercoagulability in 33 of 39 dogs (85%) based on the coagulation index.14 Interestingly, in a report describing 19 cats with primary IMHA, thromboembolic complications were not observed in any cat.13 The pathogenesis of thrombus formation in canine IMHA has not been elucidated but is likely multifactorial. Given the evidence that platelets from dogs with primary IMHA circulate in an activated state based on increased platelet P-selectin expression (alpha granule glycoprotein that is exteriorized following platelet activation),15 lowdose aspirin therapy (0.5 mg/kg/day) is now commonly administered for thromboprophylaxis,5 yet prospective studies are needed to document its efficacy. A prospective study evaluating unfractionated heparin therapy in dogs with primary IMHA revealed that a dose of 300 IU/kg SC q 6 hours was insufficient to attain anti-Xa activity of 0.35 U/mL during the first 40 hours of therapy in 10 of 18 dogs.12 At this time there is no uniform consensus on the drug (aspirin, unfractionated heparin, or low molecular weight heparin) and dosage schedule that would provide the most effective thromboprophylaxis in dogs with primary IMHA.

PROGNOSIS

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SELECTED REFERENCES

1. Rozanski EA, Callan MB, Hughes D, et al. Comparison of platelet count recovery with use of vincristine and prednisone or prednisone alone for treatment for severe immune-mediated thrombocytopenia in dogs. J Am Vet Med Assoc 2002;220:477-481. 2. Whelan MF, O'Toole TE, Chan DL, et al. Use of human immunoglobulin in addition to glucocorticods for the initial treatment of dogs with immune-mediated hemolytic anemia. J Vet Emerg Crit Care 2009;19:158-164. 3. Bianco D, Armstrong PJ, Washabau RJ. A prospective, randomized, double-blinded, placebo-controlled study of human intravenous immunoglobulin for the acute management of presumptive primary immune-mediated thrombocytopenia in dogs. J Vet Intern Med 2009;23:1071-1078. 4. Callan MB, Preziosi D, Mauldin E. Multiple papillomavirus-associated epidermal hamartomas and squamous cell carcinomas in situ in a dog following chronic treatment with prednisone and cyclosporine. Vet Dermatol 2005;16:338-345. 5. Weinkle TK, Center SA, Randolph JF, et al. Evaluation of prognostic factors, survival rates, and treatment protocols for immune-mediated hemolytic anemia in dogs: 151 cases (1993-2002). J Am Vet Med Assoc 2005;226:1869-1880. 6. Piek CJ, Junius A, Dekker A, et al. Idiopathic immune-mediated hemolytic anemia: treatment outcome and prognostic factors in 149 dogs. J Vet Intern Med 2008;22:366-373. 7. Gregory CR, Stewart A, Sturges B, et al. Leflunomide effectively treats naturally occurring immune-mediated and inflammatory diseases of dogs that are unresponsive to conventional therapy. Transplant Proc 1998;30:4143-4148. 8. Bianco D, Hardy RM. Treatment of Evans' syndrome with human intravenous immunoglobulin and leflunomide in a diabetic dog. J Am Anim Hosp Assoc 2009;45:147-150. 9. Mason N, Duval D, Shofer FS, et al. Cyclophosphamide exerts no beneficial effect over prednisone alone in the initial treatment of acute immune-mediated hemolytic anemia in dogs: a randomized controlled clinical trial. J Vet Intern Med 2003;17:206-212. 10. Horgan JE, Roberts BK, Schermerhorn T. Splenectomy as an adjunctive treatment for dogs with immune-mediated hemolytic anemia: ten cases (2003-2006). J Vet Emerg Crit Care 2009;19:254-261. 11. Putsche JC, Kohn B. Primary immune-mediated thrombocytopenia in 30 dogs (1997-2003). J Am Anim Hosp Assoc 2008;44:250-257. 12. Breuhl EL, Moore G, Brooks MB, et al. A prospective study of unfractionated heparin therapy in dogs with primary immune-mediated hemolytic anemia. J Am Anim Hosp Assoc 2009;45:125-133. 13. Kohn B, Weingart C, Eckmann V, et al. Primary immune-mediated hemolytic anemia in 19 cats: diagnosis, therapy, and outcome (1998-2004). J Vet Intern Med 2006;20:159-166. 14. Sinnott VB, Otto CM. Use of thromboelastography in dogs with immune-mediated hemolytic anemia: 39 cases (20002008). J Vet Emerg Crit Care 2009;19:484-488. 15. Weiss DJ, Brazzell JL. Detection of activated platelets in dogs with primary immune-mediated hemolytic anemia. J Vet Intern Med 2006;20:682-686.

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COMPANION ANIMAL: Immune-Mediated Diseases

SIRS, MODS AND SEPSIS: PATHOPHYSIOLOGY AND DIAGNOSIS

Erica L. Reineke, VMD, DACVECC

Assistant Professor, Emergency and Critical Care Medicine ­ Matthew J. Ryan Veterinary Hospital University of Pennsylvania, School of Veterinary Medicine Philadelphia, PA

INTRODUCTION

The systemic inflammatory response (SIRS) describes the clinical syndrome which develops when there is widespread activation of an inflammatory response either to an infectious or non-infectious insult. Normally at a site of tissue damage or injury, a localized inflammatory response develops that is designed to protect the host. However, if inflammation is severe, "overflow" of mediators into the systemic circulation can occur resulting in numerous global abnormalities that can have life threatening consequences. Ultimately if left untreated, SIRS results in multiple organ dysfunction syndrome (MODS) and death. The distinction between SIRS and sepsis centers upon the presence or absence of infection. In other words, sepsis is SIRS plus an identifiable infection.

DEFINITIONS

· · · · · Systemic Inflammatory Response (SIRS): the clinical syndrome of systemic inflammation which results from either an infectious or non-infectious insult. Sepsis: the clinical syndrome of systemic inflammation which results from infection (bacterial, viral, protozoal or fungal). Severe Sepsis: sepsis complicated by dysfunction in one or more organs. Septic Shock: acute circulatory failure and persistent arterial hypotension despite adequate volume resuscitation associated with sepsis. Multiple organ dysfunction syndrome (MODS): physiologic derangements in endothelial, coagulation, cardiopulmonary, renal, nervous, endocrine, and gastrointestinal systems associated with the systemic inflammatory response syndrome.

PATHOGENESIS OF SIRS & MODS

The pathophysiological mechanisms responsible for the generation of the SIRS are complex and incompletely understood. The initial insult that stimulates SIRS can come from a variety of sources including trauma, burns, aspiration, pancreatitis, or the products of both gram-positive and gram-negative bacteria. The induction of systemic inflammation may initially start locally (i.e. an abscess localized to a limb) but can lead to systemic signs when "mediators" enter the circulation causing global activation of inflammation. Although mediators such as platelets, polymorphonuclear leukocytes, and the endothelium also play a role, it appears that the stimulation of macrophages and release of inflammatory cytokines are pivotal in the generation of SIRS. During gram-negative sepsis, the lipid A portion of lipopolysaccharide (LPS), the glycolipid component of the cell wall, binds to LPS binding protein (LBP). This LPS-LBP complex binds to membrane bound CD14 on macrophages. This binding leads to activation of macrophages and initiates intracellular signaling to start transcription of inflammatory cytokines. The cytokines that are generated include tumor necrosis factor (TNF)-, IL-1, IL-6, IL-8 and interferon-. In addition to proinflammatory mediators, the response also generates anti-inflammatory cytokines such as IL-4, IL-10, IL-13, and transforming growth factor . This compensatory anti-inflammatory response is often referred to as CARS. In addition to LPS, low oxygen tension, acidosis, extracellular adenosine triphosphate (ATP), and pro-inflammatory molecules such as thrombin that result from tissue injury and stress can also result in the activation of macrophages. While cytokines trigger a beneficial inflammatory response that promotes local coagulation to confine tissue damage, the excessive production of these pro-inflammatory cytokines can be even more dangerous than the original stimulus, overcoming the normal regulation of the immune response and producing the clinical signs notably seen in patients with SIRS. When the immune system is fighting pathogens, these cytokines signal immune cells, such as T-cells and macrophages, to travel to the site of infection. In addition, cytokines activate these recruited immune cells stimulating

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them to produce even more cytokines. This production of a "cytokine storm" and global activation of white blood cells ultimately overwhelms the compensatory anti-inflammatory response and is a key component in the pathogenesis of SIRS. In addition to systemic activation of white blood cells, other pathologic effects of inflammatory mediators include: increased capillary permeability, vasodilation, activation of coagulation, myocardial dysfunction, and mitochondrial dysfunction. These pathologic effects of systemic inflammation can lead to the syndrome of multiple organ dysfunction or MODS. MODS is characterized by abnormalities in organs that were not affected by the original insult and is associated with a high morbidity and mortality rate. Organs at risk for dysfunction include: lungs, cardiovascular (heart and vasculature), kidneys, gastrointestinal tract, endocrine, nervous, and coagulation systems. Mitochondrial dysfunction leading to a reduction in cellular ATP is thought to be an important player in the development of organ dysfunction and/or failure. The failure of mitochondria is thought to occur secondary to tissue ischemia that results from circulatory collapse, microcirculatory changes, and hypoxemia. In addition, mitochondria may be damaged (or inhibited) by reactive nitrogen and oxygen species. However, in the lungs, acute respiratory distress syndrome (ARDS) is thought to result directly from inflammation not from mitochondrial dysfunction. The resulting organ damage may be permanent or may resolve once the underlying cause of inflammation has been cured.

CLINICAL SYNDROME & DIAGNOSIS

Clinical manifestations of SIRS and sepsis are often non-specific and will vary depending on the underlying disease process. Historical findings will also differ and may be non-specific such as a loss of appetite and depression. Physical examination findings such as fever, brick red mucous membranes, tachypnea, tachycardia, and bounding pulses may be common in patients in the hyperdynamic phase of SIRS and sepsis. However, as disease progresses, the patient may develop hypotension, pale mucous membranes, and hypothermia. It is important to note that dogs and cats differ in their manifestations of SIRS. Cats do not develop red mucous membranes and are more likely to have a relative bradycardia and hypothermia. Interestingly, in cats with septic peritonitis, abdominal pain was a rare finding. Patients in which SIRS and/or sepsis is suspected should have complete blood count, biochemistry analysis, urinalysis, and coagulation testing performed. In veterinary patients, the most common hematologic abnormalities noted with sepsis include leukocytosis, leukopenia, increased percentages of bands, toxic neutrophils, thrombocytopenia and coagulation abnormalities. Cats are frequently anemic whereas dogs will often have an elevated hemtocrit reflecting hemoconcentration secondary to volume depletion, splenic contraction or a combination of both. Changes in the serum biochemistry panel are typically reflective of the underlying disease process. With progression of disease, the biochemical profile may reveal progressive organ dysfunction. Variable abnormalities in blood glucose in dogs with sepsis are reported. Decreased serum albumin is a common finding. This is likely due to loss of albumin (either lost from the body or into interstitial spaces resulting from vascular permeability), hepatic dysfunction or preferential synthesis of acute phase proteins by the liver. Hyperbilirubinemia is also a common finding in small animal patients with sepsis. This is thought to occur secondary to cholestasis in dogs and may be secondary to hemolysis in cats. Coagulation testing may reveal abnormalities associated with disseminated intravascular coagulation (DIC) such as prolonged prothrombin time and partial thromboplastin time, and elevated d-dimers and fibrinogen degradations productions (FDP's). Additional diagnostic evaluation of a patient with suspected SIRS/sepsis should include venous or arterial blood gas measurements, blood pressure, ECG, and pulse oximetry to assess for hypoxemia. Many patients will have a metabolic acidosis reflecting poor tissue perfusion secondary to hypovolemia and increases in lactate. Criteria proposed for the diagnosis of SIRS has been extrapolated from the human medical literature for use in dogs and cats. In one veterinary study of both septic and non-septic dogs, criteria that had the greatest sensitivity for the diagnosis of SIRS were determined (Table 1). In cats, proposed criteria for SIRS were derived from a retrospective study of cats with severe sepsis identified at necropsy (Table 1). In this study, bradycardia was identified in 16% of cats, highlighting the difference between the dog's and the cat's physiologic response to sepsis. Patients must have two of the four criteria present in order for the diagnosis of SIRS to be made.

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Dogs Cats Temperature (oF) <100.6 or >102.6 <100 or >104 Heart Rate (beats/minute) >120 <140 or >225 Respiratory Rate (breaths/minute) >20 >40 WBC (x103 ); % bands <6 or >16; >3% >19 or <5 Table 1. Proposed criteria for the diagnosis of SIRS in dogs and cats In addition to the above criteria, other parameters which may support the presence of systemic inflammation include: altered mental status, interstitial edema, alterations in blood glucose (ether hyperglycemia in the absence of diabetes or hypoglycemia). Patients with septic shock are often hemodynamically unstable and will have continued arterial hypotension despite volume resuscitation, elevated mixed venous oxygen saturation (supporting mitochondrial dysfunction) and evidence of persistent hyperlactatemia. A diagnosis of sepsis can be made once infection is documented and the patient fulfills at least two of the four criteria listed in Table 1 for SIRS. The patient's history and physical examination may initially help to determine where to start looking for the source of infection. In addition, thoracic and abdominal imaging (radiography and ultrasonography) should be performed in all patients with suspected SIRS or sepsis. Samples, if it is safe, should be collected for culture and sensitivity testing to identify the cause of sepsis and to direct anti-microbial therapy. Blood, urine, peritoneal or thoracic effusion, joint fluid, CSF, endotracheal or bronchoalveolar wash fluid, or organ aspirates could all be considered as possible sources of samples to be cultured. Gram-negative enteric bacteria are the most commonly implicated organisms in sepsis in dogs and cats. However, mixed infections and gram-positive infections have also been described.

STAGING SEPSIS

The clinical syndromes of SIRS and sepsis are inherently difficult to define. This lead to the adoption of PIRO (Table 2), a method developed in order to describe the clinical manifestations of infection and the host's response to it. This method was developed during the 2001 International Sepsis Definitions Conference. In this method, PIRO is an acronym for predisposition, infection, response and organ dysfunction. PIRO provides a framework in which patient factors are incorporated along with the microbial insult in order to stage the disease process and identify factors that may contribute to morbidity and mortality. Although this method was originally developed for use in septic human patients it can be adapted for use on veterinary patients. PIRO Predisposition Present Age, Species, gender, breed, concurrent illness Future Genetic susceptibility of the host to an abnormal or inappropriate inflammatory response and enhanced understanding of the host response to infectionInsu Detection of microbial products (i.e. LPS, bacterial DNA) Markers of inflammation (CRP, IL-6) Host responsiveness (ICAM-1, cortisol, LBP) Specific targets of therapy (APC) Measures of cellular response to insult or infection (cytopathic hypoxia, apoptosis)

Insult or Infection Response

Culture and sensitivity of infecting organisms SIRS, clinical and clinicopathologic signs of sepsis and septic shock

Organ Dysfunction

Clinicopathologic abnormalities suggesting organ dysfunction Number of failing organ systems Table 2: PIRO system for staging sepsis

APC: Activated protein C, CRP: C-reactive protein, ICAM-1: intracellular adhesion molecule-1, IL-6: interleukin-6, LBP: lipopolysaccharide binding protein, LPS: lipopolysaccharide. From: Mittleman Boller E, Otto CM. Sepsis. In: Silverstein DC, Hopper K (eds). In: Textbook of small animal critical care medicine, Saunders, St. Louis, 2009.

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REFERENCES

Mittleman Boller E, Otto CM. Sepsis. In: Silverstein DC, Hopper K (eds). Textbook of small animal critical care medicine, Saunders, St. Louis, 2009. De Laforcade AM. Systemic inflammatory response syndrome. In: Silverstein DC, Hopper K (eds). Textbook of small animal critical care medicine, Saunders, St. Louis, 2009. Delligner RP et al. Surviving sepsis campaign guidelines for management of severe sepsis and septic shock. Crit Care Med 2004;32:858-873. Beal AL, Cerra FB. Multiple organ failure syndrome in the 1990s: systemic inflammatory response and organ dysfunction. JAMA 1994;271(3):226-233. Brady CA, Otto CM, Van Winkle TJ, et al. Severe sepsis in cats: 29 cases (1986-1998). J Am Vet Med Assoc; 217(4):531-535.

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COMPANION ANIMAL: Immune-Mediated Diseases

SIRS, MODS, AND SEPSIS: TREATMENT, MONITORING AND CASE EXAMPLES

Deborah Silverstein, DVM, DACVECC

Assistant Professor of Critical Care ­ Matthew J. Ryan Veterinary Hospital University of Pennsylvania, School of Veterinary Medicine Philadelphia, PA

INTRODUCTION

Timely treatment and intensive monitoring of patients suffering from SIRS, MODS, or sepsis is of utmost importance for maximizing survival. Patients with evidence of cardiovascular shock require emergent therapy in order to minimize further tissue ischemia and cellular damage. Although there is no "magic bullet" for the treatment of patients suffering from SIRS, MODS, or sepsis, and it is likely that an individual patient's genetic predisposition plays an important role in determining the inflammatory response of these patients, aggressive empiric treatment and supportive care are crucial. The primary aims of treatment include circulatory support, antimicrobial therapy, and goal-directed supportive measures.

TREATMENT OF SIRS, MODS, AND SEPSIS

FLUID THERAPY Patients suffering from SIRS, MODS, and/or sepsis commonly have subjective and objective evidence of poor perfusion. Optimization of cardiovascular function is therefore a primary goal in the management of these patients in order to maximize oxygen delivery to the tissues and minimize cellular ischemia/organ damage. Aggressive fluid therapy is the cornerstone of treatment to increase preload and thus cardiac output. Isotonic crystalloids, hypertonic crystalloid solutions, synthetic colloids and blood component therapy may be used during intravascular fluid resuscitation and maintenance of the patient with SIRS, MODS, or sepsis. The choice of fluid type(s) depends on the overall clinical picture, but general guidelines can be helpful. Isotonic crystalloid solutions remain the cornerstone of treatment for patients with SIRS, MODS, or sepsis. For animals with evidence of cardiovascular shock (non-cardiogenic), a dose of up to one blood volume of isotonic crystalloid solution (90 mL/kg in the dog and 50 mL/kg in the cat) can be given. Generally, 1/3-1/2 of the shock dose is administered as quickly as possible, followed by additional boluses as indicated by clinical parameters and repeated physical examination. Following administration, there is rapid distribution of the crystalloids into the extracellular fluid compartment so that only ~25% of the delivered volume remains in the intravascular space by 30 minutes after infusion. Routine fluid therapy is also important for animals that are cardiovascularly stable in order to maintain an adequate level of hydration and perfusion. It is important that excessive fluid volumes are not administered to avoid volume overload, especially in patients that may have vascular leak syndromes. Hypertonic (7.0-7.5%) sodium chloride administration may be useful for the treatment of cardiovascular instability in animals that do not have interstitial dehydration. Hypertonic saline causes a transient osmotic shift of water from the extravascular to the intravascular compartment. It is administered in small volumes (5 mL/kg) intravenously over approximately 10 minutes. In addition to pulling fluid into the intravascular space, there is evidence that it may also be beneficial to reduce endothelial swelling, increase cardiac contractility, cause mild peripheral vasodilation, and modulate the inflammatory response. Due to the osmotic diuresis and rapid redistribution of the sodium cations that ensue following the administration of hypertonic saline, the intravascular volume expansion is transient (<30 minutes) and additional fluid therapy (either isotonic crystalloids or synthetic colloids) must therefore be used with hypertonic saline. Colloids are large molecules (molecular weight >20,000 daltons) that do not readily sieve across the vascular membrane and may therefore be especially useful in hypoproteinemic animals with SIRS, MODS, and sepsis. These fluids are hyperoncotic to the normal animal and therefore pull fluid into the vascular space. They cause an increase in blood volume that is greater than that of the infused volume and help to retain this fluid in the intravascular space (assuming normal capillary permeability). Hydroxyethyl starch solutions, primarily hetastarch solutions, are most commonly used in small animal patients and are suspended in an isotonic crystalloid solution. Dextran 70 has also been studied in dogs and cats, but is currently off the market. The recommended dose of hetastarch is up to 20 mL/kg in the dog and up to 10 mL/kg in the cat for the treatment of shock (note: rapid administration of hydroxyethyl starch in the cat has been reported to cause

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vomiting). Continuous rate infusions of 1-2 mL/kg/hr can be used to increase the oncotic pressure in animals that are hypoproteinemic. Excessive volumes of synthetic colloid solutions can lead to volume overload, coagulopathies, and hemodilution. Hetastarch solutions can also be used with isotonic or hypertonic crystalloids to maintain adequate plasma volume expansion with lower interstitial fluid volume expansion and to expand the intravascular space with smaller volumes over a shorter time period. Animals suffering from cardiovascular instability can also be given a combination of hypertonic saline and a synthetic colloid in order to prolong the effect of bolus fluid therapy. A 1:2.5 ratio of 23.4% sodium chloride with dextran 70 or hetastarch will make a ~ 7.5% saline mixture (44 mL of 23.4% NaCl in 106 mL of hydroxyethyl starch). This may be useful as a small volume resuscitation fluid, especially in large animals or those with evidence of intracranial hypertension and shock. The need for blood products in patients with SIRS, MODS, and/or sepsis is often dependent on the patient's disease process and clinical picture. Animals with recent blood loss that are unresponsive to fluid therapy alone may benefit from red blood cell administration, especially if the hematocrit has fallen below 25-30%. However, excessive increases in hematocrit should be avoided since this will increase blood viscosity. In addition, many of these animals are coagulopathic and should be treated with fresh frozen plasma if the clotting times are outside of the normal range. Some patients with inflammatory disease will also benefit from anticoagulant therapy once the coagulation times are normalized in order to prevent further depletion of the clotting factors, as is typically seen in animals with disseminated intravascular coagulation. Packed red blood cells and fresh frozen plasma are administered at a dose of 10-15 mL/kg and fresh whole blood at a dose of 20-25 mL/kg. Refrigerator-stored plasma or frozen plasma that is more than 1 year old no longer contains platelets or the labile coagulation factors (V, VIII, and vonWillebrands). Platelets are only present in fresh blood within 24 hours of collection and their use is indicated in animals with thrombocytopenia/pathia-induced bleeding disorders or massive hemorrhage (eg severe ITP-induced hemorrhage). Plasma products are most commonly used in animals with severe hypoalbuminemia, profound blood loss, or a coagulopathy. Its ability to increase colloid osmotic pressure is limited compared to the hyperoncotic synthetic colloids, but it does supply albumin, an important carrier of certain drugs, hormones, metals, chemicals, toxins and enzymes. Blood products should be administered over at least 1-2 hours in order to monitor for a transfusion reaction and avoid volume overload, but it may be necessary to bolus these products in lifethreatening situations. A blood type should be determined in all animals, especially cats, before transfusions are given. Cross-matching will also help to decrease the incidence of transfusion reactions. Animals with SIRS, MODS, and/or sepsis that have severe hypoalbuminemia may benefit from treatment with 25% human albumin. Albumin is crucial in the transport of drugs, hormones, chemicals, toxins, and enzymes. Preliminary studies in dogs showed that human albumin administration in dogs increased circulating albumin concentrations, total solids, and increase colloid osmotic pressure, although the effect on mortality remains unknown. More recent data, however, has described sensitization, acute and delayed reactions, and potentially lethal complications from human albumin administration to normal dogs. The product is currently used in critically ill animals that are severely hypoproteinemic and have anticipated ongoing losses or are at high risk for complications related to the marked hypoalbuminemia. The recent release of canine and feline albumin solution provides an exciting new possibility for the use of species-specific, natural colloid resuscitation. Preliminary data on its use in 5 research dogs was encouraging, but further research is needed before this product can be recommended. VASOPRESSOR AND INOTROPE THERAPY SIRS, MODS, and sepsis can all lead to hypotension despite intravascular volume resuscitation (shock), therefore necessitating the use of vasopressor and/or inotrope therapy. Since both cardiac output and systemic vascular resistance affect oxygen delivery to the tissues, therapy for hypotensive patients includes maximizing cardiac function with fluid therapy and inotropic drugs and/or modifying vascular tone with vasopressor agents. Commonly used vasopressors include catecholamines (epinephrine, norepinephrine, dopamine) and the sympathomimetic drug phenylephrine. In addition, vasopressin, corticosteroids, and glucagon have been used as adjunctive pressor agents. Different sympathomimetics cause various changes in the cardiovascular system, depending on the specific receptor stimulation caused by the drug. Conventionally, adrenergic receptor location and function involves the alpha-1 and beta-2 receptors located on the vascular smooth muscle cells that lead to vasoconstriction and vasodilation, respectively, while beta-1 receptors in the myocardium primarily modulate inotropic and chronotropic activity. In addition, there are

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dopaminergic-1 receptors in the renal, coronary, and mesenteric microvasculature that mediate vasodilation and dopaminergic-2 receptors in the synaptic nerve terminals that inhibit the release of norepinephrine. Dopamine has various potential actions on adrenergic and dopaminergic receptors. Primarily dopaminergic effects are seen at low intravenous doses (1-5 mcg/kg/min), mainly beta-adrenergic effects are seen at moderate doses (5-10 mcg/kg/min), mixed alpha- and beta- adrenergic effects are present at high doses (10-15 mcg/kg/min), and primarily alpha-adrenergic effects are seen at very high doses (15-20 mcg/kg/min). The actual dose response relationship is unpredictable in a given patient because it is dependent on individual variability in enzymatic dopamine inactivation, receptor down regulation, and the degree of autonomic derangement. Dopamine can be used as a single agent therapy to provide both inotropic and pressor support in animals with vasodilation and decreased cardiac contractility. Despite dopamine's beneficial effects on cardiac output and blood pressure, it may have deleterious effects on renal, mesenteric, and skeletal blood flow. Norepinephrine (NE) has mixed alpha and beta-adrenergic receptor agonism with preferential alpha- receptor activity. Therefore, the effects on heart rate and contractility are mild, and NE is commonly used as a pressor agent in animals with normal or increased cardiac output states. The vasopressor dose of NE in humans (and extrapolated to dogs) is 0.05-3.3 mcg/kg/min intravenously. Epinephrine (epi) is a potent pressor with mixed alpha- and beta-agonist activity. Although epi is thought to have more potent beta-agonist effects than NE, individual response is quite variable in patients with systemic inflammatory diseases and hypotension. Epi may significantly impair splanchnic blood flow compared to other vasopressor drugs. The vasopressor dose of intravenous epi is 0.01-0.1 mcg/kg/min and for primarily beta-agonist effects is 0.005-0.02 mcg/kg/min. Epi is rarely used as a sole first-line vasopressor agent due to it s potential side effects, but may be necessary in critically ill animals. Phenylephrine is a pure alpha agonist drug that causes profound vasoconstriction. It has been shown to cause an increase in cardiac output and blood pressure, presumably due to increased venous return to the heart and activation of alpha-1 receptors in the myocardium. Phenylephrine is typically used in patients that are unresponsive to other sympathomimetics, although it can be used as a sole first-line agent in vasodilated, hypotensive animals. Since phenylephrine has no beta-agonist activity, it is the least arrhythmogenic of the sympathomimetic pressor drugs and is therefore desirable in animals that develop tachyarrhythmias in response to other pressor agents. The intravenous dose range is 0.5-3 mcg/kg/min. Dobutamine is a beta-agonist with no alpha effects. It increases cardiac output, oxygen delivery, and oxygen consumption without causing vasoconstriction. It is therefore useful in animals with cardiac insufficiency. Dobutamine may worsen or precipitate tachyarrhythmias and may precipitate seizure activity in cats. The intravenous dose range is 1-5 mcg/kg/min in cats and 2.5-20 mcg/kg/min in dogs. Vasopressin is a non-adrenergic vasopressor agent. It has both direct and indirect effects on the vascular smooth muscle via the V1 receptors and induces vasoconstriction in most vascular beds. In vitro, vasopressin is a more potent vasoconstrictor than phenylephrine or NE. At low doses, this drug causes vasodilation in renal, pulmonary, mesenteric, and cerebral vasculature in an attempt to maintain perfusion to these vital organs. Low flow states secondary to hypovolemia or septic shock are associated with a biphasic response in endogenous serum vasopressin levels. There is an early increase in the release of vasopressin from the neurohypophysis in response to hypoxia, hypotension, and/or acidosis, which leads to high levels of serum vasopressin. This plays a role in the stabilization of arterial pressure and organ perfusion in the initial stages of shock. There appears to be a subsequent decrease in circulating vasopressin levels, most likely due to a depletion of hypothalamic stores. The use of vasopressin in animals in the later stages of shock, especially those that exhibit vasodilation and are refractory to catecholamine therapy, may therefore be beneficial. The drug also enhances sensitivity to catecholamines and therefore may allow the dose of concurrent catecholamine therapy to be lowered. Experimental studies in dogs have demonstrated an increase in blood pressure and cardiac output with minimal side effects. A clinical case series using vasopressin at 0.5-4 mU/kg/min found an increase in blood pressure following vasopressin therapy as well. This drug will require further investigation, but may be considered in animals with catecholamine resistant vasodilatory shock, as is commonly seen in animals with SIRS, MODS, and sepsis. The incidence of relative adrenal insufficiency in small animals suffering from SIRS, MODS, and/or sepsis has not been clearly elucidated, but some animals with refractory hypotension may benefit from physiologic steroid treatment. An ACTH stimulation test may be suggestive of a relative adrenal insufficiency in these cases (ie delta cortisol <3 mcg/dL), but further research is needed.

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ANTIMICROBIAL THERAPY Early and appropriate antibiotic therapy is crucial for the treatment of patients with proven or suspected sepsis, especially those with clinical evidence of SIRS or MODS. Blood, urine, respiratory secretions (collected by endotracheal wash, transtracheal wash or bronchoscopy) and/or other available body fluids (i.e., pleural, peritoneal or cerebrospinal fluid) should be obtained for analysis and culture, as indicated, prior to initiating antimicrobial therapy. Broad-spectrum antibiotic therapy should be administered pending culture and sensitivity results. Empirical antibiotic choices should be effective against gram-positive and negative organisms, as well as anaerobes. Initial combinations might include ampicillin (22 mg/kg IV q6-8h) and enrofloxacin (15 mg/kg IV q24 h in dogs, 5 mg/kg IV q24h hours in cats), ampicillin and amikacin (15 mg/kg IV q24 h), cefazolin (22 mg/kg IV q8h) and amikacin, ampicillin and ceftazidime (22 mg/kg IV q8h), or clindamycin (10 mg/kg IV q8-12h) and enrofloxacin. Single agents such as ticarcillin/clavulanic acid (50 mg/kg IV q6h), cefoxitin (15-30 mg/kg IV q4-6h), or imipenem (5-10 mg/kg IV q6-8h, if bacterial resistance is suspected) could be used initially as well. GASTROINTESTINAL PROTECTION Stress-related mucosal disease (SRMD) and subsequent upper gastrointestinal (GI) bleeding are frequently seen in critically ill humans with SIRS, MODS, and sepsis and may also occur in dogs and cats. Clinical signs of hematemesis, hematochezia, or melena should alert the clinician to potentially serious GI hemorrhage. Hypoperfusion of the upper GI mucosa, excessive gastric acid secretion and impaired mucosal defense mechanisms (mucous secretion, production of growth factors) contribute to the development of SRMD. Patients with SIRS and MODS, especially those with hepatic failure, renal failure, or prolonged anorexia, as well as those receiving high-dose corticosteroids or non-steroidal anti-inflammatory drugs, are at highest risk for GI hemorrhage. The incidence of SRMD in veterinary patients is unknown and therefore no guidelines exist for its management. The initial strategy in critically ill dogs and cats should be to ensure adequate GI perfusion and employ early enteral nutrition. High-risk patients should receive pharmacologic prophylaxis for stress-related GI hemorrhage. Based on the currently available evidence in human medicine, it appears that proton pump inhibitors (PPI) are superior to histamine-2 receptor antagonists (H2RA), which are superior to sucralfate in the prevention of SRMD in adult critical care patients. Drugs available include omeprazole (PPI) 0.7-1.0 mg/kg PO q24h, pantoprazole (PPI) 0.7-1.0 mg/kg IV q24h, famotidine (H2RA) 0.5-1.0mg/kg IV q12-24h, PO, ranitidine (H2RA) 0.5-4 mg/kg IV q8-12h and sucralfate (protectant) 0.25-1gm/25kg PO q6-8h. Recent evidence suggests that ranitidine does not decrease acid production in dogs at clinically recommended doses, but further research would be helpful. NUTRITION Following initial stabilization of the patient with SIRS, MODS, and/or sepsis, nutritional status should be addressed. Adequate nutrition is critical in patients with secondary hypermetabolic states such as sepsis. The enteral route (orally or via nasoesophageal, esophagostomy, gastrostomy, or jejunostomy tube) is preferable if the animal is normotensive, not vomiting, and alert. Parenteral nutrition should be administered if the enteral route is not feasible or contraindicated. If the blood glucose falls below 60 gm/dL, 0.5 mL/kg of 50% dextrose should be diluted 1:1 with sterile water and administered intravenously over 1-2 minutes. The fluids should also be supplemented with dextrose as needed (2.5-7.5%). Hyperglycemia should be avoided since it has been associated with an increased likelihood of infection and a poorer prognosis. MONITORING Septic patients should be closely monitored since minute-to-minute changes in the animal's condition may require continuous adjustments or interventions. Frequent physical examinations, body weight, PCV/TS, blood glucose, electrolytes, blood gas values, coagulogram, urine output, blood pressure, EKG, pulse oximetry, and central venous pressure should be closely followed and repeatedly assessed. Below are some general guidelines to maximize tissue perfusion and prevent organ ischemia: 1. 2. 3. 4. 5. 6. Maintain PCV >25% in animals with acute anemia secondary to loss or lysis of red blood cells. Keep colloid osmotic pressure >16 mmHg or total solids >4.5 gm/dL in animals with acute hypoproteinemia. Consider the use of synthetic colloids +/- plasma therapy in these patients. Maintain clotting times within the normal range with plasma administration as needed. Keep the blood glucose within the normal range, if possible. Supplemental dextrose or insulin therapy may be necessary. Keep electrolytes within the normal range, if possible. Ensure a mean arterial pressure of 70 mmHg (not higher than 130 mmHg).

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Aim for a heart rate of 70-120 beats per minute (may be breed dependent). Treat arrhythmias as needed. Watch closely for evidence of an increase in respiratory rate or effort since this is often the first sign of volume overload/pulmonary edema. 9. Ensure a urine output of at least 1-2 mL/kg/hour. Fluid therapy +/- diuretics may be necessary. 10. Keep hemoglobin saturation (pulse oximeter reading) above 93% or PaO2 greater than 80 mmHg using oxygen supplementation needed. Inspired oxygen concentrations of <60% should be used, if adequate, to prevent oxygen toxicity. 11. Keep central venous pressure between 0-10 cm H2O.

7. 8.

CONCLUSION

Prognosis in patients with SIRS, MODS, and sepsis depends on the underlying disease process and the stability of the cardiovascular system. Regardless, sepsis and SIRS is associated with a very high morbidity rate, with mortality rates in humans ranging from 20-40%. Novel therapies have been researched, including anti-endotoxin antibodies, anti-TNF antibodies, and substances that affect the coagulation system, with mostly negative outcomes. Recently, activated Protein C, involved in the fibrinolysis arm of the coagulation cascade, has shown promise in improving overall mortality in septic people, but its use in animals is not well delineated. Sepsis and SIRS may result in severe cardiovascular abnormalities, coagulation disturbances, multiple organ failure, acute lung injury, and death. Immediate recognition of the clinical presentation is vital to the success of treatment of affected patients. Aggressive and immediate fluid resuscitation to provide adequate tissue perfusion and oxygenation improves the outcome in these critically ill patients. The underlying cause must be diagnosed early, as many cases require emergent surgical intervention once the cardiovascular system has been stabilized, and correction of anemia, coagulopathy, acid/base disturbances, and electrolyte imbalances have been attempted. Prognosis must be considered guarded in patients with septic shock and SIRS, especially if organ failure or acute lung injury is present. Depending on the underlying cause, early and aggressive treatment with fluids, colloids, plasma, antibiotics, and resection of infected tissue can result in full recovery.

Case examples will be presented. References are available upon request.

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COMPANION ANIMAL: Dentistry and Oral Surgery

ENERGIZE YOUR HOSPITAL'S DENTISTRY SERVICES

Bonnie Miller, RDH, BS

Staff Dental Hygienist ­ Matthew J. Ryan Veterinary Hospital University of Pennsylvania, School of Veterinary Medicine Philadelphia, PA During these difficult economic times all professionals are seeking ways to increase profits. For veterinarians, the avenue to elevation of quantity and quality of diagnostic and treatment services lies within the practice's dental department. Making a commitment to invest in up-grading your dental services will include an investment in acquiring new knowledge and skills for you and your entire staff, along with an expenditure for new dental equipment necessary to properly diagnose and treat oral/dental disease. Dental education is an absolute must for each team member. Assistants, technicians and veterinarians should all be "on the same page" as far as understanding the basics of dentistry. Each professional who will be interacting in any way with the patient needs to have a thorough knowledge base of dental terminology, nomenclature and the numbering system of teeth. It is important for each team member to be able to recognize the appearance of normal oral anatomy of the soft tissues and dental structures in the mouth in order to be able to recognize abnormalities of those structures that may require further investigation and treatment procedures. Basic and advanced dental education is available for veterinarians and staff members in many formats and locations across the country. Whether you and your staff choose to attend conferences, register for on-line dental courses or consult with dental professionals to provide in-office seminars and wetlabs, the opportunities for elevating your dental knowledge base are plenty. Once you have made the commitment to allotting time and money there will need to be a change in attitude concerning the portrayal of the dental services. Rather than just scheduling patients for "a dental", the practice that envelops the concept of providing high quality oral/dental care will be scheduling patients for oral disease diagnosis and treatment. The financial ability to purchase the necessary dental equipment may determine decisions made as to the extent of professional dental services offered. At minimum, most veterinary practices are capable of performing a professional dental cleaning on an intubated anesthetized patient. These minimum services require use of power and hand scalers and a polisher with prophy angle and prophylaxis paste. For those practices who believe the patient is only scheduled for "a dental", no further equipment is needed, however, in current practice, limiting the treatment to a basic cleaning is no longer acceptable. In order to provide a higher level of professional dental service to include the diagnostics and treatment of oral disease, additional instruments, equipment and knowledge are required as accepted standard of care. In 2005, the Dental Care Guidelines Task Force of the AAHA provided guidelines for the practice of dentistry in the general veterinary setting. To elevate the dental practice to today's standards, a dental chart, a periodontal probe and dental explorer must be used to perform a thorough oral exam and dental charting during the dental treatment appointment. In addition, no dental assessment is conclusive without the use of intraoral radiography. The clinical evaluation cannot reveal disease or abnormalities concealed below the soft tissues or within the bone or tooth structures. Unless intraoral radiographs are used, there can be no assurance given to the client that their pet's mouth is healthy, even though the teeth may be sparkling clean. In studies conducted in 1998 at the University of California (Vertstraete, F. et al, AJVR), full mouth radiographs were determined to be justified and of diagnostic value in dogs and cats. In that study, incidental and clinically important findings were documented in 69.5% of dogs having no clinical abnormalities. A similar study for cats documented 46.5% with incidental and clinically important findings. Consider that if these pets were your patients, without imaging, they would have left your practice with a clean mouth and a false sense that the mouth was healthy! Whether using traditional film-based systems or the more expensive digital technology, it is imperative that staff members become knowledgeable in processing techniques (bisecting angle, occlusal and parallelism), safety, technological features, storage, etc. Without proper instruction given, the staff frustration levels often are cause for the equipment to sit idle. The decision to incorporate intraoral radiography into your practice requires the purchase of the image source machine which can be wall mounted or mobile. Today's dental radiographic machines have settings that offer a choice of methods of acquiring the images. The traditional method that uses intraoral film is less expensive initially, requiring the purchase of

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the three or four sizes of film, a chairside developer box, processing solutions, and accessories such as clips, drying racks, and storage envelopes or film mounts. The digital method of acquiring images reduces the patient's exposure to radiation by up to 90%. Digital imaging is environmentally friendly because there are no chemicals to contaminate water systems. The digital images can be visualized within a few seconds following exposure, thus reducing the amount of time that the patient is under anesthesia, and, also allowing for quick retakes if errors in positioning require correcting. The storage and retrieval of patient images is easy; the images can be electronically transferred to patient records or to specialists for consultation. Three types of digital imaging are commonly being used in veterinary medicine today. They include the charge-coupled device (CCD) detector, the Complementary-Metal-Oxyde-Semiconductor (CMOS) detector and the photostimulable phosphor (PSP) detector. The major disadvantage of digital systems is the initial cost of the equipment (sensors, software and hardware), a possible $15,000 expense. Another disadvantage is that the CCD and CMOS use sensors that are limited in size, only similar to sizes of # 0 or #2 standard dental films. In many patients, the use of a larger #4 film is preferable although not available in a sensor. The phosphor plate (PSP) is available in the #4 sizes, however, that technology requires manipulation of the plate similar to that of standard film with only slight savings in time. Most dental specialists prefer to utilize traditional film techniques for larger patients and digital technology for smaller patients. To properly provide dental extraction services, sectioning of the teeth is essential. For this, equipment must include a dental delivery system with a few high and low speed handpieces and an air/water syringe. These systems can be basic or elaborate, with suction, swivel attachments, and fiber optic light sources, and can be run with air pressure provided by either nitrogen or an air compressor. A selection of various burs used to cut bone and split teeth are necessary to use in correct extraction techniques. It is also helpful to have more than a few extraction and periosteal elevators on hand as there is such a wide difference in sizes of teeth within the mouth and from patient to patient. In addition to the above listed equipment necessary to diagnose and treat the patient, a high quality dental practice will have a table with drainage, ergonomically designed clinicians' stools, an instrument washer and steam autoclave, a good dental or surgical light, and magnification for the clinicians. A top of the line equipped dental suite may also include a water filtration system, handpiece lubricator, electrosurge unit and soft tissue laser. Whether you are interested in taking baby steps to better equip your dental service or you choose to undertake a major overhaul, include your tax professional and your local dental equipment supplier in your planning. Once the plan is executed, enjoy the satisfaction and rewards gained from your capabilities of providing the high standards of oral/dental diagnosis and treatment that is expected of you by your clients.

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COMPANION ANIMAL: Dentistry and Oral Surgery

RECOGNIZING COMMON ORAL PATHOLOGY

Alexander M. Reiter, Dipl. Tzt., Dr. med. vet., DAVDC, EVDC

Assistant Professor & Chief, Dentistry and Oral Surgery Service ­ Matthew J. Ryan Veterinary Hospital University of Pennsylvania, School of Veterinary Medicine Philadelphia, PA

PERIODONTAL DISEASE

The periodontium is a functional unit consisting of the gingiva, periodontal ligament, alveolar bone and cementum. Periodontal disease is inflammation and infection of the periodontium due to plaque bacteria and the host's response to the bacterial insult. Gingivitis is the reversible form of periodontal disease, affecting gingiva only. As inflammation continues, the gingiva detaches from the tooth, creating a periodontal pocket, and a shift occurs in the gingival flora from a gram-positive aerobic to a gram-negative anaerobic spectrum. Release of endotoxins and enzymes from bacteria and white blood cells is tissue-destructive. Periodontitis is the more severe form of periodontal disease, affecting all tissues of the periodontium and resulting in attachment loss, gingival recession, periodontal pocket formation and loss of alveolar bone. The loss of alveolar bone is usually irreversible, and with increasing bone loss the tooth becomes mobile and ultimately exfoliates. The goal of periodontal therapy is elimination of supra- and subgingival plaque and associated microflora and surgical reduction of periodontal pockets.

STOMATITIS

Stomatitis is a disease seen largely in the adult cat and is characterized by persistent chronic inflammation of the oral (and pharyngeal) mucosa. The etiology of feline stomatitis is poorly understood, but feline calicivirus (FCV) and feline herpesvirus-1 (FHV-1) are suspected to play an important role. Other conditions in cats and dogs that manifest as acute or chronic oral inflammation or ulceration include autoimmune disease (e.g., pemphigus vulgaris, bullous pemphigoid, discoid lupus erythematosus), erythema multiforme (e.g., perivasculitis from drug eruptions), foreign body reactions, thermal injuries, etc. Cats with stomatitis often present with a long history of difficulty swallowing, bead breath, drooling of saliva due to reluctance to swallow, inappetence/anorexia, weight loss, pawing at the face, and pain upon eating. Oral lesions typically appear as focal or diffuse inflammation involving the gingiva, alveolar mucosa, labial and buccal mucosa, sublingual mucosa, and the mucosal region lateral to the palatoglossal fold. The goal of treatment is aimed at controlling oral plaque and decreasing the inflammatory and immunologic response. Medicinal treatment options include local and systemic administration of immunosuppressive, immunomodulatory/immunostimulatory, anti-inflammatory, antiseptic and/or antibiotic medications. Surgical treatment options include partial and full-mouth tooth extraction and laser therapy.

GINGIVAL HYPERPLASIA

Enlargement of the gingiva is often due to gingival hyperplasia (an increase in the number of normal cells in a normal arrangement) and may result from chronic or acute inflammatory disease. Gingival hyperplasia is also caused after administration of anticonvulsants, cyclosporine and calcium channel blockers. Gingivectomy and gingivoplasty are performed to remove excess gingiva.

TOOTH WEAR

Abrasion is tooth wear caused by contact of a tooth with a non-dental material (such as a tennis ball or cage bars). Attrition is tooth wear caused by tooth-to-tooth contact (such as when a maloccluding tooth contacts another tooth). If tooth wear removes enamel and dentin faster than odontoblasts can form dentin, the pulp may either succumb to prolonged chronic inflammation or become exposed, inflamed and necrotic.

TOOTH FRACTURE

If the fracture involves enamel only, the consequences are minimal. If dentin is exposed, bacteria could pass through dentinal tubules to the pulp. A tooth fracture is called complicated when it exposes the pulp. Crown-root fractures are fractures that involve the crown and root(s) of the tooth. It can be uncomplicated or complicated. A root fracture is a fracture involving the root (far more common with than without pulp exposure). If uncomplicated fractures with near pulp exposure and complicated fractures are left untreated, pulp necrosis ultimately results. Canine tooth fractures are usually due to hit-by-car trauma, falls from heights, kicks and hits. Certain working dogs are more prone to fracture of canine teeth if their distal tooth surfaces are weakened by wear from chewing on cage bars. Carnassial tooth fractures (fractures of the

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maxillary fourth premolars or mandibular first molars) in dogs are often caused by chewing on very hard objects. Tooth resorption is typically the cause of crown fracture in cats, with root fragments remaining in the alveoli.

TOOTH DISPLACEMENT INJURY

Luxation is a clinically or radiographically evident tooth displacement within its alveolus. Lateral and extrusive luxation is most common and often associated with alveolar fracture. Intrusive luxation of canine teeth into the nasal cavity may sometimes occur in patients with severe periodontal disease. Avulsion is complete extrusive luxation, with incisors and canine teeth most often involved in dogs. The success of reimplantation of an avulsed tooth is greatly influenced by the length of time that the tooth is out of the alveolar socket. Luxated and avulsed teeth require repositioning, stabilization, and root canal therapy due to the likely loss of blood supply to the pulp.

ENDODONTIC AND PERIAPICAL DISEASE

Pulpitis can either be reversible or irreversible. Pulp necrosis is a sequel of an untreated irreversible pulpitis, a traumatic injury or events that cause long-term interruption of the blood supply to the pulp. When infection and inflammation spread through the apical foramina into the periapical region, periapical disease develops. A (peri)apical cyst can form when scattered epithelial cells within the periodontal ligament proliferate after chronic irritation of the apical periodontal ligament from pulpitis or pulp necrosis. If such a tooth is extracted without removing the cyst lining around the root apex, a residual cyst remains. A (peri)apical granuloma is caused by bacteria and endotoxins that leak from a necrotic pulp through the apical foramina into the periapical region, resulting in extensive demineralization of bone and radiographically evident lesions. A (peri)apical abscess can either be acute with painful, purulent exudate accumulating around the apex or present an acute exacerbation of a granuloma. Clinical signs include facial swelling, pain, and fever and general malaise in more advanced cases. An intra- or extraoral sinus tract may develop. Treatment is tooth extraction or root canal therapy.

OSTEOMYELITIS

Osteomyelitis is a local or generalized inflammation of bone and bone marrow and usually due to bacterial or, less commonly, fungal infection. Osteomyelitis can arise from an endodontic infection, an infection through the periodontal space, an extraction wound, open jaw fracture or metastasis from a local or remote area of infection. If untreated the acute form may progress to a chronic form, eventually leading to bone necrosis. There are few anecdotal reports of multiquadrant osteomyelitis with osteonecrosis of the jaws in dogs, and little is known about the etiology, presentation, diagnosis and treatment of this disease. Treatment involves tooth extraction, aggressive debridement and administration of systemic antibiotics.

TOOTH RESORPTION, TOOTH EXTRUSION AND ALVEOLAR BONE EXPANSION

Tooth resorption (with multiple teeth in more than one jaw quadrant involved) is very common in cats. Most affected animals will not show distinct clinical signs. Signs related to oral pain include dropping food while eating, reluctance to eat hard food, and spontaneous repetitive lower jaw motions. Tooth resorption is otherwise asymptomatic as long as the resorptive process remains below the gingival attachment (not exposed to oral bacteria) and does not affect the pulp. The cause of tooth resorption in cats is unknown, but excessive dietary intake of vitamin D has been proposed to play a role. Dentoalveolar ankylosis and replacement resorption occur when the root surfaces fuse with surrounding alveolar bone, thus including the tooth in the normal remodeling process of bone. When replacement resorption occurs or progresses coronally towards the gingival attachment apparatus, an inflammatory component may join the initially non-inflammatory lesion. Both replacement resorption and inflammatory resorption can be present on the same tooth. In advanced stages of tooth resorption, the crown fractures off, leaving root remnants behind. Some cats show abnormally extruded canine teeth, accompanied by thickening of alveolar bone. An association between tooth extrusion, alveolar bone expansion and tooth resorption has been reported. Teeth with resorption, those with excessive extrusion, and root remnants are extracted. Ankylosed teeth and those with roots undergoing replacement resorption may be treated by means of crown amputation and intentional root retention.

CARIES

Caries is the result of demineralization of the tooth surface by acids that are formed during fermentation of highly refined carbohydrates by cariogenic bacteria. It is rare in companion animals. Teeth with caries are either extracted or treated endodontically.

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MALOCCLUSION

Orthodontics deals with the diagnosis and treatment of dental and skeletal malocclusion. The goal of orthodontic treatment is to provide the patient with a pain-free and functional bite. If orthodontic treatment is performed in an intact dog or cat, neutering should be performed to prevent that the animal is bred and malocclusion inherited to offspring. Interceptive orthodontics is defined as extraction of deciduous or permanent teeth that cause malocclusion. Rather than performing extraction or orthodontic movement, the crown of a maloccluding tooth that causes trauma to adjacent structures may be reduced in length. This requires sterile instrumentation, surgical crown reduction, partial vital pulpectomy, direct pulp capping, and restoration of the pulp chamber. A direct inclined plane is utilized for treatment of lingually displaced mandibular canine teeth, with composite build up around maxillary canines and incisors and deflecting slopes made to create spaces for the mandibular canines to bite into. Buttons and elastic chains are used for treatment of mesially displaced maxillary canine teeth. The goal is to create an anchorage unit between two to three maxillary premolars and molars to ensure a larger combined root surface compared to that of the canine tooth to be moved. This can be accomplished by wiring and splinting several teeth together, forming an anchorage unit. Then orthodontic buttons are cemented to the anchorage unit and to the canine tooth to be moved. An elastic chain is placed in between the buttons.

JAW FRACTURE

Traumatic jaw fractures occur after motor vehicle trauma, falls, kicks, gunshots, and fights with other animals. Pathologic jaw fractures are often secondary to periodontal disease, oral neoplasia, and metabolic abnormalities. Common sites for mandibular fracture in dogs are the premolar/molar region and the area distal to the canines. In cats, the mandibular symphysis and the condylar process are more likely involved. Fractures of the upper jaw are often multiple. Epistaxis, facial swelling, pain, and asymmetry are the usual physical findings, with or without crepitus and subcutaneous emphysema. Radiographs should always be obtained to assess tooth injuries and define fracture sites. Initially, the mouth is flushed with dilute chlorhexidine, and the fracture sites are carefully debrided. Bone fragments that could contribute to the stability of fracture repair should be retained. Healthy teeth in fracture lines also can be retained but should be monitored for any evidence of periodontal or endodontic disease. There are various ways to repair jaw fractures, including maxillomandibular fixation (e.g., adhesive tape muzzle, bridging between upper and lower canine teeth), circumferential wiring (e.g., mandibular symphysis wire cerclage), interdental wiring with intra-oral composite splinting (e.g., when teeth can be used as anchor points), osseous wiring (e.g., in edentulous areas), external skeletal fixation (e.g., in cases with missing bone fragments, severe comminution, and edentulous bone segments), bone plating (e.g., utilizing mini-, intermediate and microplates), and partial mandibulectomy or maxillectomy (e.g., when tissues are already necrotic).

TEMPOROMANDIBULAR JOINT LUXATION

Trauma is usually the cause of temporomandibular joint (TMJ) luxation. With rostrodorsal TMJ luxation the involved mandibular condyle moves rostrally and dorsally. Consequently, the lower jaw shifts laterorostrally to the contralateral side. Malocclusion then results in the inability of the animal to close its mouth fully due to tooth-to-tooth contact (between the maxillary and mandibular canine and cheek teeth on the contralateral side). Reduction of rostrodorsal TMJ luxation is achieved by placing a wood dowel (or a hexagonal pencil in smaller animals) between the maxillary fourth premolar and mandibular first molar teeth on the affected side only (dowel acts as a fulcrum) and closing the lower jaw against the dowel while simultaneously easing the jaw caudally. Tape muzzling for 2 to 4 weeks will prevent the animal from opening the mouth wide, thus reducing the likelihood of recurring luxation. Chronic luxation is treated by means of unilateral condylectomy.

OPEN-MOUTH JAW LOCKING

Open-mouth jaw locking has primarily been reported in Bassett hounds and Persian cats. Yawning often precipitates an event. The coronoid process of the mandible flares laterally, locking onto or lateral to the zygomatic arch. The animal presents with its mouth wide open, but in contrast to rostrodorsal temporomandibular joint (TMJ) luxation there is no tooth-to-tooth contact. An ipsilateral protuberance on the ventrolateral aspect of the zygomatic arch may be palpable. Both joints can be affected, and manual locking of the apparently unaffected side should be attempted under chemical restraint prior to surgical treatment (surgery may need to be done on both sides). Open-mouth jaw locking can also occur as a result of traumatic events that caused flattening of or excessive callus formation at the zygomatic arch, malunion fracture of the mandibular body, and increased mandibular symphyseal laxity. Acute treatment consists of opening the jaw further (sedation may be needed) to release the coronoid process from the ventrolateral aspect of the zygomatic arch, and then closing the mouth. Tape muzzling is a temporary solution. Definitive surgical treatment involves partial coronoidectomy, partial zygomectomy, or a combination of both procedures.

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TEMPOROMANDIBULAR JOINT ANKYLOSIS

Ankylosis may result from trauma to the TMJ and callus formation during healing of fractured bones forming the joint. It may also be due to extensive new bone formation associated with otitis media and craniomandibular osteopathy. Ankylosis results in a progressive inability to open the mouth. An example of a false (extracapsular) ankylosis would be the fusion between a fractured zygomatic arch and a coronoid process without TMJ involvement. Surgical treatment is dependent on the nature and location of the lesion. Radiographic features of true (intracapsular) ankylosis are loss of the TMJ space and irregular new bone formation. Treatment consists of condylectomy and excision of all associated osteophytes. Recurrence of ankylosis is common despite meticulous bone removal.

CRANIOMANDIBULAR OSTEOPATHY

This disease of unknown etiology is seen primarily in 3 to 7-month old West Highland White, Scottish, and Cairn Terriers. Puppies present with swelling of the lower jaws, inappetence, lethargy and fever. They are reluctant to open the mouth and very resentful on palpation of the cranium, temporomandibular joints (TMJs) and lower jaw. Distinctive histological and radiographic features include bilateral, extensive, irregular, periosteal new bone formations along the mandibles, TMJs, tympanic bullae, and the calvarium. Long-term treatment with corticosteroids is recommended. The condition tends to run an undulant course, and symptoms may regress at about one year of age (in puppies that survive).

MASTICATORY MYOSITIS

Masticatory myositis (also called masticatory muscle myositis) is an autoimmune disease that selectively involves the masseter, temporal, and medial and lateral pterygoid muscles in dogs. Inflammation, necrosis and phagocytosis are limited to the 2M myofibers in these muscles, and there is circulating IgG directed against the unique myosin component of these fibers. Acute (painful muscle swelling) and chronic stages (progressive muscle atrophy) are both associated with difficulty or inability to open the mouth. Untreated episodes may last 2 to 3 weeks. Relapses frequently occur in weeks or months. A definitive diagnosis of masticaory myositis can be made if clinical and histologic signs of inflammation are limited to the masticatory muscles, and antibodies against type 2M fibers are identified in serum and/or in immune complexes within the masticatory muscles. A 2M fiber serum antibody titer may not always be diagnostic (e.g., in dogs with chronic masticatory myositis or when corticosteroids have been administered prior to blood collection). Therefore, a muscle biopsy should be performed in addition to a 2M fiber serum antibody titer. Prednisone (1-2 mg/kg PO BID for first few weeks) is slowly tapered over 8-12 months to the lowest possible alternate-day effective dosage.

ORAL TUMORS

Oral tumors may be of dental (odontogenic) or nondental origin. In dogs, viral papilloma, peripheral odontogenic fibroma, acanthomatous ameloblastoma, malignant melanoma, squamous cell carcinoma and fibrosarcoma are most commonly diagnosed in the mouth. In cats, the predominant oral tumors are squamous cell carcinoma and fibrosarcoma. Incisional or excisional biopsy should always be performed in patients that present with suspicious oral lesions. Conservative resection is restricted to benign lesions. Peripheral odontogenic fibromas are likely to regrow after resection at a tissue level that does not include the tooth and its periodontal ligament from which they arise. Invasive tumors should not be treated by conservative surgery. Radical resective surgery (mandibulectomy, maxillectomy, glossectomy, lip and cheek resection) may provide a cure in many cases of oral and maxillofacial malignancy and is tolerated surprisingly well by dogs and cats. The multiple anesthesia episodes required for radiation therapy and the systemic sickness and multiple office visits required for chemotherapy are avoided. Combined therapy may be indicated, particularly for tumors with local or distant metastasis.

DENTIGEROUS CYST AND UNERUPTED TEETH

The epithelial lining of a dentigerous (tooth containing) cyst around the crowns of unerupted teeth may in some cases undergo neoplastic metaplasia. Therefore, unerupted teeth should be extracted utilizing an open extraction technique, and any epithelial cyst lining should be removed and submitted for histopathological examination. Commonly affected are the mandibular first premolars in brachycephalic dogs (e.g., Boxers).

PALATE DEFECTS

Palate defects may be congenital or acquired after birth. Congenital palate defects may appear as harelip, cleft of the lip and most rostral hard palate, cleft hard and soft palate, or midline cleft or unilateral defect of the soft palate only. Rarely, the soft palate may be absent. Acquired palate defects include oronasal fistula due to severe periodontal disease of a maxillary tooth, traumatic cleft palate often associated with falling from heights or hit-by-car trauma in cats, and lesions that result from electric cord injury, gunshot trauma, animal bites, foreign body penetration and maloccluding teeth. Clinical signs of patients with palate defects include failure to create negative pressure for nursing and poor weight gain (in

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immature patients), nasal discharge, sneezing, nasal reflux, rhinitis, coughing, gagging, tonsillitis, and aspiration pneumonia. Congenital hard palate clefts are repaired with an overlapping flap technique, and congenital soft palate clefts are repaired with a medially positioned flap technique. Repair of a unilateral soft palate defect is facilitated by unilateral tonsillectomy prior to flap surgery. A medially positioned flap technique with is utilized for treatment of a traumatic cleft palate. Large caudal palate defects are repaired with a modified split palatal U-flap. Combination of overlapping flaps and buccal- or labial-based pedicle or axial pattern flaps may be required for repair of large palate defects, which are advanced, rotated, transposed and sutured across the defect 6 to 8 weeks following extraction of several teeth. These flaps are supplied by major palatine or infraorbital blood vessels. Tongue flaps may be used for defects in the rostral or mid-portion of the hard palate. Another alternative is to create a permanent or removable acrylic or silicone obturator.

PROCEEDINGS: Companion Animal ­ Dentistry and Oral Surgery (sponsored by Pfizer Animal Health)

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Wednesday, March 3, 2010 Thursday, March 4, 2010 Philadelphia, Pennsylvania

COMPANION ANIMAL: Dentistry and Oral Surgery

DIETS, TREATS, ANTIBIOTICS AND VACCINATIONS: PREVENTING DRAGON BREATH

Colin Harvey, BVSC, FRCVS, DACVS, DAVDC

Professor of Surgery and Dentistry ­ Matthew J. Ryan Veterinary Hospital Univeresity of Pennsylvania, School of Veterinary Medicine Philadelphia, PA

INTRODUCTION

Periodontal disease, the most common disease in companion animals, is easily prevented. No build-up of dental plaque, no disease. It really is that simple. However, achieving excellent plaque control over the lifetime of a companion animal is challenging. Good oral hygiene in companion animals requires collaboration among the owner, the animal and the veterinarian, preferably from the time when the permanent teeth are starting to erupt. In an adult dog, if plaque control has been poor and there is substantial accumulation of hard dental calculus (tartar), professional dental scaling is an essential first step, as ongoing oral hygiene can only be successful if the surface of the tooth is clean to start with. Teeth scaling requires general anesthesia ­ subgingival examination and scaling cannot be accomplished satisfactorily in an awake patient. Beware of "anesthesia-free dental scaling", offered by some groomers and other individuals with no professional training or license. Full dental scaling requires examination and if necessary scaling sub-gingivally, which is impossible to achieve. Thus the end result of anesthesia-free dental scaling even in a cooperative patient is typically a mouth that looks clean (because visible surfaces of teeth have been scaled) but often with extensive sub-gingival plaque and calculus deposition. Since the area of disease (gingivitis, periodontitis, osteomyelitis) is subgingival, there is no real benefit to the patient. A thorough dental scaling procedure consists of inspection and charting of the teeth, supra and subgingival scaling, root planing, tooth polishing, pocket irrigation and home care instruction. Performed competently in a dog with extensive periodontitis, it can require 2-3 hours of professional working time under anesthesia, and is rarely completed in less than 30 minutes even in an animal with minimal calculus accumulation. It is a prophylactic procedure, in that it removes the plaque that causes periodontal disease and the calculus that harbors the plaque. Some veterinary technicians are skilled in prophylaxis procedures; however, prophylaxis should not be left only to a technician ­ it involves diagnosis and treatment decisions, and the mouth should be checked before and after the scaling procedure by a veterinarian. Oral-dental examination includes probing. Dental probes have a rounded tip and a depth marking system and are used to examine periodontal pockets - a toothbrush applied at the correct angle cannot reach a depth of more than 4 to 5 mm, so pocket depth measurement (and assessment of mobility and inspection of the gingiva around each tooth) is essential. Successful retention of teeth with stage 3 or 4 periodontal disease requires good collaboration between the veterinarian, owner and a cooperating animal. Charting is strongly recommended. It documents extent of disease for comparison with subsequent examinations and ensures that the indication for the procedure to be performed (scaling, scaling plus periodontal surgery or extraction) is documented. Antibiotics are over-used in association with periodontal procedures.

TEETH SCALING AND POLISHING

Scaling an animal with well-established periodontitis is not a minor procedure. Gross calculus deposits are removed using calculus forceps or dental extraction forceps, avoiding damage to the gingiva. An ultrasonic scaler is used to remove supragingival plaque and calculus. It is easier and quicker than hand scaling. Water flow is essential to cool the oscillating tip and flush away the debris. Gently stroking the tooth with the side of the instrument tip is best, and the tip must not be pressed firmly against the tooth surface or kept in contact with the same area for more than a few seconds. Using gentle technique and appropriate scaling tips, ultrasonic scalers may be used subgingivally. Gently insert the tip into the pocket with the unit inactivated, then activate the unit as the tip is withdrawn from the pocket.

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Ultrasonic scalers cause contamination of the immediate environment with bacteria-laden water droplets; protective eyeglasses and face masks should be worn, and sterile surgical procedures should not be performed in the same work area. Although ultrasonic instruments can be used to accomplish most of the work, use of hand instruments is often required to perform a complete scaling procedure. The most important hand instrument is the curette. This has a sharp working side edge and a rounded tip. It is inserted gently into the pocket until resistance is felt. Tilt the curette away from the tooth to engage the sharp edge against the root surface as it is pulled firmly out of the pocket. To determine if a root is thoroughly clean, gently run a curette over the surface - it will skip over areas of remaining calculus. If the surfaces cannot be properly cleaned using closed curettage, a flap is raised and 'open curettage' is performed. Tooth surface irregularities created by instrumentation during scaling are smoothed out by polishing the teeth. A mildly abrasive prophylaxis paste' is applied to the surface of the teeth with a rubber cup mounted in a slow speed (5000rpm) prophylaxis handpiece. Following polishing, the gingival pocket is irrigated to flush out debris. A surface conditioner designed to reduce adhesion of plaque and calculus is now available (OraVet, Merial); the professional agent is applied immediately post-prophylaxis and periodic use of the home application is recommended as a follow-up.

MANAGEMENT OF DEEP PERIODONTAL POCKETS

For deep periodontal pockets (anticipated to be deeper than about 5mm following healing) or where the entire attached gingiva has been lost or the tooth is mobile, additional periodontal surgical treatment is needed. Indications and techniques for management of involved periodontal treatment are not considered in this session.

PERIODONTAL HOME CARE

In both dogs and cats, plaque and calculus deposition tends to occur fastest and most heavily on the buccal surfaces of the teeth. Fortunately, these are the most readily accessible surfaces. The most important aspect is compliance of the owner and animal with a continuing program designed to retard plaque and calculus formation. For most owners, the most practical way is to have the animal do the work. A natural diet for carnivores requires the animal to tear food material, which has a natural flossing action. Chewing materials that mimic a natural diet are raw meaty bones, rawhides or other chews. Large hard biscuits are also somewhat beneficial, particularly those that include a chemical anti-calculus agent such as polyphosphate (e.g. hexametaphosphate). Standard kibble dry food fed dry is only moderately effective in retarding plaque accumulation compared with canned food in dogs. Dentally-effective diets are now available. The Veterinary Oral Health Council® Seal of Acceptance has been awarded to products with documented effectiveness in retarding accumulation of plaque and or calculus (www.VOHC.org). If the owner can be persuaded, daily tooth brushing is the ideal plaque and calculus retardant. Any tooth brush, used consistently over all buccal tooth surfaces will be effective. A soft-bristle pediatric brush is a sensible combination for dogs. Cat-sized tooth brushes are available. Making brushing into an enjoyable activity for the patient is key ­ the owner will see this as time spent playing with the animal instead of as a chore which the animal clearly does not like. Palatability makes a huge difference. Unfortunately, the anti-plaque agent that is most effective chemically (chlorhexidine, e.g. CHX, Virbac) is less palatable that less chemically-effective products. Another palatable plaque retardant is CET dentifrice (Virbac). Other chemical agents are now marketed.

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As for the human mouth, regular (6 months, preferably) re-evaluation helps ensure that oral hygiene is being maintained effectively.

COMBINATION ORAL HYGIENE

A combination of techniques (brushing, dental diet, treats) is more likely to be effective than a single technique, and periodic veterinary examination is part of the mix. The importance of good home care needs to be taught to the owner - take time in the office to discuss the possibilities and demonstrate good application techniques.

RESULTS FOLLOWING CONSERVATIVE PERIODONTAL THERAPY

When home oral hygiene removes plaque thoroughly daily or every other day, the periodontal tissues stay in a clinically healthy condition. The two factors that determine long-term results in dogs are the extent of disease existing prior to treatment (e.g. presence or absence of pocketing or furcation involvement that promotes plaque retention) and the efficacy of long-term plaque retardation. Few owners are scrupulously conscientious about oral hygiene in their pets, and thus there is a broad range of clinical effectiveness.

USE OF ANTIBIOTICS AND VACCINES

Periodontal disease is an infection. Every mouth has a rich microbiological flora and contains structures that do not have a vascularized epithelial covering. This combination makes the concept of `infection' in the mouth complex compared with other tissues. In addition to `periodontopathogenic' organisms, bacteria commonly found in the mouth include organisms considered to be primary pathogens when cultured from other tissues ­ e.g. Staphs and Streps of every type, coliforms, Proteus, Pseudomonas, Pasteurella. These organisms will be found on culture of e.g. stomatitis lesions as well as in periodontal pockets; however, their role in causing non-periodontal infections has not been investigated. Periodontal disease, caused by periodontopathogens in the dental plaque biofilm, is by far the most common infection encountered in small animal practice. As the plaque biofilm matures and gingival inflammation starts to develop, the plaque biochemical environment becomes richer, allowing anaerobic periodontopathogens, including spirochetes, to thrive. The ability of an individual animal to resist a given gingival bacterial load varies greatly, depending on immunological competence, differences in protective constituents of oral fluids, and other factors such as age, stress, nutritional status, concurrent infections, distant-organ health status and probably additional factors that are incompletely understood or not yet known. What is the purpose of an antibacterial drug when an infection is located in a tissue that is always exposed to a rich bacteriological flora? Is re-infection the inevitable result following antibacterial treatment? In a healthy mouth, the well vascularized oral tissues are adapted to existing in a contaminated environment. Considerations of the patient's general health aside, patients with contaminated oral sites that are already open for drainage (i.e. periodontal pockets) or that will be open for drainage following a procedure such as scaling or extraction generally do not require antibiotic treatment. Thus a patient with extensive periodontal disease treated by a combination of scaling and extraction is, of itself, not an indication for treatment with an antibacterial drug. Indications for Use of Antimicrobial Drug in Patients with Oral Infection: Treatment of Local Infection An antibiotic can shift the plaque flora from a pathogenic to a commensal mix. Combining this effect with the mechanical removal of calculus and plaque will enhance the likelihood of stabilization of healthy flora in the healing tissues. Indications: 1. Local tissues that are severely infected and treatment including retention of teeth would require periodontal surgery that will expose infected bone, or teeth surrounded by severely infected bone are to be extracted. The local tissues will withstand the effects of surgery better and healing will be more rapid if local periodontal infection is controlled at the time of the dental procedure. In this circumstance, antimicrobial treatment is commenced several days prior to surgery and is continued for several days following surgery.

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2. When the periodontal infection has progressed to wide-spread osteomyelitis (i.e. is affecting the trabecular bone and outer cortical bone of the involved jaw) and infected bone will be left in place following extraction or deep scaling. Antimicrobial treatment is best started several days prior to the procedure, and continued for several weeks following the dental procedure. 3. When mucosal immunopathy has resulted in oral ulceration that is exacerbated by contact with even small amounts of dental plaque accumulation, such as in ulcerative stomatitis in dogs and stomatitis in cats. Prevention of Bacteremia Bacteremia is frequent in patients with gingivitis and active periodontitis, and is rapidly cleared by the reticulo-endothelial system in otherwise healthy patients. However, there is an association between severity of periodontal disease and distant organ abnormalities. Treatment with an antibiotic drug is indicated when the patient's distant tissues are at risk as a result of bacteremia during a dental procedure. Examples of indications for prevention of bacteremia: 1. Patients with clinically evident cardiac disease. Although a cause-and-effect relationship between periodontal infection and endocarditis has not been proven, turbulent flow in an abnormally functioning heart may enhance the attachment of bacteremic organisms to the heart valves. 2. Patients with clinically-evident renal or hepatic disease, or with uncontrolled hormonal disorders such as diabetes mellitus or hyperadrenocorticism. When cellular metabolism is depressed by systemic disease, the oral tissues are less able to respond normally to the trauma of the procedure, and the kidney and liver may be at risk of infection from bacteria that become lodged in sludged blood vessels. 3. Patients with prostheses, such as ocular prosthesis, total hip replacement or cruciate ligament repair using a nonabsorbable material, or patients whose spleen has been resected (the spleen is a primary site of the reticulo-endothelial filter that eliminates bacteremia within several minutes in healthy patients). 4. Patients in which a clean surgical procedure will be performed during the same anesthetic episode, such as an older dog with a mammary mass and severe periodontal infection. In this case, continuation of the antimicrobial treatment for several days post-operatively is recommended to ensure that any bacteria trapped in blood clots are exposed to an effective concentration of the antimicrobial drug. 5. Patients with immunopathies or who are undergoing treatment with immune-suppressive drugs, such as cancer chemotherapy or for treatment of severe skin diseases and other severe reactive or auto-immune disorders. A broad-spectrum bactericidal antibiotic that achieves a high concentration in serum is indicated. Peri-operative treatment is all that is required (single dose orally the morning of the procedure, or IV during induction of anesthesia, repeated every 2-3 hours during prolonged procedures). Which Antibiotic to Select? Broad-spectrum or narrow-spectrum? When an antimicrobial drug is administered to treat periodontal infection, it must be effective against the pathogenic organisms likely to be present, and must reach an effective concentration in serum and periodontal pocket fluid. Because of the breadth of the oral flora, and the possibility that bacteria may be pathogenic locally or as a result of bacteremia, a broad-spectrum antibiotic is indicated to ensure effectiveness against local and contaminating pathogens. Culture and Sensitivity Testing or Not? Because of the microbiological challenges noted previously and the delay in treatment that would result, bacterial culture and susceptibility testing are rarely performed in oral disease patients. Specific Antibiotic: Based on susceptibility testing of gingival samples from a group of patients with gingivitis, the most broadly effective antimicrobial drug currently approved for use in dogs and cats is amoxicillin-clavulanic acid. For deep-seated, long-standing periodontal bone infections, clindamycin has good activity against oral anaerobes, but has less broad-based aerobic activity compared with amoxicillin-clavulanate.

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Metronidazole is effective against oral anaerobes, but has no aerobic bacterial activity; it is particularly effective for both short-term and long-term/intermittent treatment of ulcerative stomatitis, though whether the beneficial effect is antibacterial or a poorly understood immunological effect on these immunopathic tissues is not yet clear. The tetracycline group of antibacterial drugs is now rarely used for peri-operative treatment during dental procedures because of the risk for development of plasmid-derived antibacterial resistance; however, there is renewed interest in the tetracycline group because, even at sub-antimicrobial doses, tetracyclines have an anti-collagenase effect that can protect periodontal tissues against inflammation-induced destruction. Doxicycline is available for local injection into periodontal pockets in an absorbable gel to provide a high concentration locally. A patient under consideration for treatment of oral infection may have no, one or two indications (local disease, distant organ prophylaxis) for use of an antibacterial drug as part of his/her dental treatment. Each of these indications may have a different recommended treatment period, and the various sub-types of local indication and systemic risk also have different recommended treatment periods. Recently, a periodontal vaccine (Porphyromonas denticanis, gulae, salivosus) was developed by Pfizer Animal Health, Inc. Safety testing is complete and clinical efficacy testing is underway. Vaccination site irritation occurs in a small number of patients. The vaccine has been shown to be effective in retarding periodontal bone loss in two animal models. Pending completion of the clinical efficacy testing, vaccination of high-risk dogs (small breed dogs, and all dogs with established periodontal disease following professional treatment) is recommended.

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110TH PENN ANNUAL CONFERENCE - 2010

Wednesday, March 3, 2010 Thursday, March 4, 2010 Philadelphia, Pennsylvania

COMPANION ANIMAL: Dentistry and Oral Surgery

FELINE STOMATITIS: WHAT WORKS?

Alexander M. Reiter, Dipl. Tzt., Dr. med. vet., DAVDC, EVDC

Assistant Professor & Chief, Dentistry and Oral Surgery Service ­ Matthew J. Ryan Veterinary Hospital University of Pennsylvania, School of Veterinary Medicine Philadelphia, PA

INTRODUCTION

The term stomatitis should be reserved to describe wide-spread oral inflammation (beyond gingivitis and periodontitis) that may also extend into submucosal tissues (e.g., marked caudal mucositis extending into submucosal tissues may be termed caudal stomatitis. Stomatitis is recognized mainly in the adult cat and characterized by persistent inflammation of the mucosa of the caudal oral cavity (bordered medially by the palatoglossal folds and fauces, dorsally by the hard and soft palate, and rostrally by alveolar and buccal mucosa), gingiva, alveolar mucosa, and buccal/labial mucosa. Purebred cats and cats living in a multi-cat household tend to develop stomatitis at a younger age. Primary differential diagnoses include autoimmune diseases, erythema multiforme, eosinophilic granuloma complex, foreign body reactions, and chemical and thermal burns.

ETIOLOGICAL CONSIDERATIONS

Feline calicivirus (FCV) can be isolated from 50 to 100% of cats with chronic oral inflammation. However, experimental attempts to reproduce persistent disease using FCV isolates from cats with stomatitis have been unsuccessful. While some studies may have underestimated the prevalence of feline herpesvirus-1 (FHV-1) in surveys of cats with stomatitis, a recent investigation found that 88% of cats with stomatitis were shedding both feline calicivirus (FCV) and feline herpesvirus-1 (FHV-1) in saliva, making these two viruses highly suspicious in playing a role in feline stomatitis. Feline immunodeficiency virus (FIV) and feline leukemia virus (FeLV), however, do not appear to play a role. It has also been suggested that acute and chronic oral inflammation may develop due to a deficient or excessive host response to the presence of plaque bacteria and their toxins. Evidence for a cause-effect relationship between Bartonella and feline stomatitis has not been provided.

PATHOGENESIS

The presence of polyclonal gammopathy and lymphocytic-plasmacytic infiltrates within stomatitis lesions in cats is indicative of an immune-mediated disease. Serum concentrations of immunoglobulins (IgG, IgM and IgA) are elevated in cats with stomatitis. About one-third of affected cats also have elevated serum IgE levels. In saliva, IgG and IgM concentrations are increased, but IgA levels are decreased which may contribute to the development and/or persistence of stomatitis by reducing the effectiveness of local oral defense mechanisms. Neutrophil function tests in cats with stomatitis have not demonstrated any significant abnormalities. The vast majority of plasma cells within the mucosal infiltrate are IgG+, and analysis of CD4+ and CD8+ cell populations revealed that CD8+ cells predominate at all stages of the disease. Analysis of cytokine mRNA expression profiles in mucosal tissues from cats with stomatitis revealed that a shift occurs from the T-helper type 1 dominated expression profile found in normal oral mucosa towards a mixed T-helper type 1 and type 2 profile in oral lesions.

HISTORY, CLINICAL SIGNS, AND ORAL EXAMINATION

Cats with stomatitis often have a long history of difficulty swallowing, drooling of blood-tinged saliva, inappetence, weight loss, pawing at the face, oral pain, and depression. Affected cats appear to be interested in food but are unwilling to eat; they also show a preference for soft foods. Clinical signs include mandibular lymphadenopathy, oral, nasal and ocular discharge, focal ulceration of the lips, focal or diffuse oral inflammation involving the gingiva, alveolar mucosa, buccal/labial mucosa, and mucosa of sublingual tissues, tongue, and the area of or lateral to the palatoglossal folds. In severe cases, the inflamed tissues become proliferative, ulcerated and bleed readily. Various degrees of dental and periodontal disease may be present (tooth resorption, gingival recession, periodontal pockets, mobile or missing teeth). Occasionally, a complete oral examination cannot be done without chemical restraint.

LABORATORY EVALUATION

A complete blood count, biochemical profile and urinalysis are performed to identify concurrent or contributory diseases. An increase in total protein usually is due to elevated globulin concentrations. Leukocytosis (mild to moderate neutrophilia

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accompanied by a mild left shift) may be present. Electrophoresis of serum proteins usually reveals a polyclonal gammopathy. Serologic evaluation for FeLV antigen and FIV antibody should be performed. Virus isolation on specimens obtained from oral swabs of inflamed tissues can be included but results do not alter treatment plan. Bacterial culture and sensitivity testing may be helpful in chronic cases that do not respond to the antibiotics commonly used for oral infections. Testing for Bartonella infection is controversial. A biopsy specimen should be obtained to rule out neoplasia or other causes of oral inflammation. Histopathology typically shows ulceration with subepithelial lymphocytic-plasmacytic infiltration.

TREATMENT

Cats with stomatitis present a therapeutic challenge, and management is often frustrating for both the veterinarian and owner. The goal of treatment is aimed at controlling oral plaque and decreasing the inflammatory and immunologic response. Plaque control can be achieved with scaling, topical and systemic antimicrobial therapy, and tooth extraction. Antibiotic therapy (e.g., amoxicillin/clavulanic acid, clindamycin, doxycycline, azithromycin) often provides only short-term clinical benefit or may be ineffective in the initial management. Topical chlorhexidine products may be used for adjunctive therapy. Corticosteroids are often required to decrease inflammation, reduce pain, and stimulate appetite. Some cats may temporarily benefit from SQ or IM injections of methylprednisolone. Anti-lymphocyte drugs such as cyclosporine may be useful (start at 2.5 mg/kg PO BID of Neoral solution; give for 6 weeks before judging effectiveness; monitor drug levels [should be 250-500 ng/ml], kidney, liver, and other blood parameters). Clinical improvement was reported in cats with stomatitis that were given bovine lactoferrin (bacteriocidal immunomodulator that may inhibit adhesion of periodontopathogens; 250 mg PO SID). Low-dose doxycycline (anti-inflammatory, anticollagenolytic, and antimetalloproteinolytic effects; 0.2-2 mg/kg PO SID) and recombinant feline interferon (Virbagen omega; not readily available in the USA; 5 MU is injected submucosally, diluted and divided as necessary to inject all inflamed areas; remaining 5 MU are injected into a 100 ml bag of sodium chloride and frozen in ten 10 ml aliquots; client gives 1 ml PO q 24h for 100 days; the 10 ml fraction in use is refrigerated and the other aliquots are kept frozen until needed) have also been suggested as medical treatment options in cats with stomatitis. Tooth extraction removes the surfaces that are available for plaque retention. Full-mouth dental radiographs are obtained. Teeth with periodontitis or resorption and retained roots must be extracted. Plaque seems to play a role in perpetuating stomatitis even if teeth are located relatively distant from the actual site of inflammation (e.g., in cases of caudal stomatitis). Therefore, healthy teeth may be extracted in cats with severe stomatitis that do not respond to medication. Extraction of all teeth caudal to the canines is often sufficient. If inflammation occurs adjacent to the canines and incisors, a full-mouth extraction procedure may be necessary. Large mucoperiosteal flaps with releasing incisions are raised, and teeth are extracted following partial alveolectomy. Debridement of inflamed soft tissue and bone prior to wound closure with an absorbable monofilament suture material will aid in resolution of inflammation. Sublingual and oropharyngeal tissues around the endotracheal tube can often become swollen from intubation and handling. Dexamethasone (0.25 mg/kg IV) may be administered to facilitate breathing after extubation. Postoperative pain control can be achieved with transdermal administration of fentanyl or oral buprenorphine. The response to tooth extraction ranges from complete resolution of inflammation (60%), minimal residual inflammation and no oral pain (20%), initial improvement requiring continued medical therapy to control clinical signs (13%), to no improvement (7%). Cats tolerate extractions, even full-mouth extractions, very well and can eat moist and even dry food without teeth. Laser surgery may be used as an adjunct in patients with refractory stomatitis not responding to extractions and medical therapy. Repeated CO2 laser treatment of inflamed oral tissues may result in dramatic improvement in some cats. The laser is used in excision and ablation modes. Fibrosis formation is enhanced when lased areas are left to heal by second intention. Follow-up oral examination typically shows granulation tissue and striations of fibrous tissue spanning the previously treated areas. Laser treatments are repeated in intervals of several weeks to months, increasing the amount of fibrous tissue and decreasing interspersed areas of continued inflammation. The patient should be seen for reexaminations every few weeks to monitor improvement, to obtain body weight measurements and to slowly taper oral corticosteroids.

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110TH PENN ANNUAL CONFERENCE - 2010

Wednesday, March 3, 2010 Thursday, March 4, 2010 Philadelphia, Pennsylvania

COMPANION ANIMAL: Dentistry and Oral Surgery

DENTAL EXTRACTIONS MADE EASIER

Alexander M. Reiter, Dipl. Tzt., Dr. med. vet., DAVDC, EVDC

Assistant Professor & Chief, Dentistry and Oral Surgery Service ­ Matthew J. Ryan Veterinary Hospital University of Pennsylvania, School of Veterinary Medicine Philadelphia, PA

INTRODUCTION

Tooth extraction is one of the most frequently performed surgical procedures in small animal practice. The most common indications for tooth extraction in dogs are periodontal disease and tooth fracture, and in cats tooth resorption and stomatitis. If the disease process is too advanced for the teeth to be saved, extraction is necessary. Financial and other considerations may lead the client to request extraction. Tooth extraction is contraindicated in patients (1) that cannot be anesthetized due to health concerns; (2) that have had radiation therapy involving the jaws that would inhibit healing; (3) with bleeding disorders that cannot be controlled; and (4) on medications that may cause prolonged bleeding times or prevent healing.

PREPARATION

Utilizing good instrumentation and applying proper techniques can help provide a stress-free and controlled procedure for the operator with minimal trauma to the patient, faster recovery and healing, and more dependable long-term results. The client's approval must be obtained for the extent and cost of treatment to avoid the potential for future litigation. Reasonable health is required when undergoing general anesthesia, which is determined by physical examination and laboratory tests. An endotracheal tube with inflated cuff and an oropharyngeal pack will prevent blood and debris from entering the trachea or esophagus. Perioperative broad-spectrum antibiotics are given in selected patients that are debilitated and immunocompromised, have organ disease, endocrine disorders, cardiovascular disease, severely contaminated wounds and systemic infections, or permanent implants and transplants. Dental radiographs should be obtained prior to tooth extraction to evaluate alveolar bone health, variations in root anatomy, and to determine the presence of dentoalveolar ankylosis or replacement resorption of roots that could potentially complicate the extraction procedure. Additional pain control is achieved by use of nerve blocks and field/infiltration blocks intraoperatively with longer-lasting local anesthetics. Safety measures include wearing of safety glasses, masks and gloves.

BIOMECHANICS

Teeth are anchored to the alveolar bone of the mandible, incisive bone and maxilla by soft tissue components of the periodontium, the gingiva and periodontal ligament. During the extraction process, these tissues must be severed (junctional epithelium and gingival connective tissue) or stretched and torn (periodontal ligament) to allow delivery of the tooth to be extracted. Gentle tissue handling is important to minimize trauma and to allow rapid healing of both soft and hard tissues. In the dog the incisors, canines, first premolars, and lower third molars are single-rooted teeth; in the cat, the incisors, canines, and commonly the upper second premolars are single-rooted. The cat's upper first molars may be treated as single-rooted teeth even though they have more than one root (the roots are usually fused together). The upper fourth premolar in the cat and dog and the upper first and second molars in the dog are three-rooted. All other teeth are tworooted.

EQUIPMENT

Dental luxators have sharp blades designed to penetrate into the periodontal space and cut periodontal ligament fibers. Blades of dental elevators are then gently worked into the space between the tooth and the alveolar bone and carefully rotated to create a slow, gentle and steady pressure on the tooth. Luxators and elevators are grasped with the butt of the handle seated in the palm and the index finger extended along the blade of the instrument to act as a stop should the instrument slip and to prevent iatrogenic damage. Extraction forceps should fit the tooth as closely as possible and be applied as far apically on the tooth as possible to reduce the chances of root fracture. They should only be applied when the tooth is very loose. An absorbable suture material is preferred for wound closure in the oral cavity so that sedation or anesthesia for suture removal can be avoided. Poliglecaprone 25 is the preferred suture material for most oral surgeries (40 for dogs; 5-0 for cats and small dogs) and persists in the mouth for about 3-5 weeks.

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TECHNIQUES

Extractions can be performed using the closed technique, i.e., without raising a mucoperiosteal flap, or open technique, i.e., raising a mucoperiosteal flap to expose alveolar bone. The procedure should always start with cutting the gingival attachment around the tooth. A luxator or elevator is then inserted between the gingival margin or alveolar bone and the tooth. Pressure is applied while slowly rotating the elevator through a small arc and holding the instrument firmly against the tissues for at least 10 seconds. As the periodontal space widens, it is helpful to change from smaller to larger instruments. When the tooth is sufficiently loose, forceps are placed as far apically on the tooth as possible, and the tooth is rotated slightly on its long axis with a steady pull and removed from its socket. Granulation tissue, debris, pus, and bony fragments are removed from the extraction site, which is rinsed with chlorhexidine digluconate prior to closure. Leaving a blood clot in the alveolus is an essential part of healing. Packing the alveolus with osteogenetic, osteoinductive or osteoconductive materials may be done in selected cases. Multi-rooted teeth require sectioning into crown-root segments, which are extracted using the same principles as for single-rooted teeth. Sectioning is performed with a cutting bur in a highspeed handpiece and water irrigation, starting from the furcation through the tooth crown. An open extraction technique is employed when a tooth resists appropriate elevation due to its size and root anatomy/pathology, or if the operator is unable to retrieve a fractured or retained root through the alveolar socket. A mucoperiosteal flap with one or two releasing incisions extending beyond the mucogingival line into alveolar mucosa is made over the tooth/teeth to be extracted. Using a periosteal elevator the flap is elevated apical to the end of the bony prominences (alveolar juga) covering the roots. Multi-rooted teeth are sectioned. Alveolar bone overlying the roots is then removed with a round bur and water irrigation by as much as 1/3 to 2/3 of the length of the root(s). The tooth or crownroot segments are then luxated, elevated and extracted. The extraction site is debrided prior to replacing the mucoperiosteal flap. To avoid tension on the closed flap, the periosteum should be incised in across the entire base of the flap. The flap is then apposed to the palatal/lingual gingiva by means of simple interrupted sutures. An alternative to complete extraction of teeth with dentoalveolar ankylosis and root replacement resorption (as seen in cats) is crown amputation with intentional root retention. The gingival attachment is incised, creating a small envelope flap. The tooth crown is amputated from the root with a cutting bur and water irrigation. The resorbing root is further reduced with a round or pear-shaped bur to about 1-2 mm below the alveolar margin. The gingiva must be sutured tension-free over the defect, and a postoperative radiograph is obtained. This technique is contraindicated for teeth with periodontitis, endodontic disease and periapical pathology.

COMPLICATIONS

Fractured Roots The entire tooth should be removed to prevent infection and inflammation of the extraction site. Dental radiography is invaluable in determining the position and size of a root fragment. Special root tip elevators, picks and extraction forceps are available. Creation of a mucoperiosteal flap and partial alveolectomy will facilitate removal of a root fragment. If a root fragment cannot be retrieved, the surgical site should be evaluated periodically by means of clinical and radiographic follow-up examination. Retrieval of root fragments from the nasal cavity, infraorbital or mandibular canal after accidental repulsion of a root fragment into these spaces may be made through soft tissue and bone away from the extraction site. Hemorrhage Digital pressure with gauze is usually sufficient to stop bleeding. Cold compresses also can reduce blood flow sufficiently to allow a clot to form and reduce postoperative swelling following flap surgery. Excessive alveolar hemorrhage is rare. The alveolus may be irrigated packed with specific materials aiding in hemostasis, and the gingiva is sutured over the packs without tension. Vasoconstrictors are not recommended. Trauma to Adjacent Structures The operator should not leverage against adjacent teeth to prevent unwanted elevation and crown fractures of teeth not to be extracted. When deciduous teeth are extracted, care should be taken not to elevate or damage the underlying tooth buds of permanent successors. Instruments must not be inserted between a deciduous canine tooth and its developing permanent successor. Gingival lacerations commonly occur during the extraction process. More severe soft tissue lacerations may result from slippage of sharp instruments.

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Sublingual Edema and Sialocele Tongue manipulation, excessive alveolar mucosa elevation at the lingual aspect of the mandible, and iatrogenic trauma can result in sublingual edema. If airway and breathing are compromised, intravenous dexamethasone is administered. Instrument slippage may also cause injury to the ducts of the sublingual and mandibular salivary glands, causing formation of a sublingual sialocele (ranula). If breathing and masticatory function are not compromised, postponing marsupialization or resection of the sublingual and mandibular gland-duct complexes should be considered because the ranula often resolves spontaneously within weeks or months. Orbital Trauma Iatrogenic orbital trauma with panophthalmitis can occur after extraction of caudal maxillary teeth. Orbital structures may be perforated by a pointed instrument particularly in patients with severe periodontitis. If antimicrobial and antiinflammatory treatment fails, enucleation may need to be performed. Fracture of the Alveolus or Jaw Excessive force can cause fracture of the alveolus or jaw. Owners of animals with severe periodontitis should be warned about an increased possibility of jaw fracture, in particular when mandibular first molar or canine teeth need to be extracted. Preoperative dental radiography is imperative. If a jaw fracture occurs, diseased teeth in the fracture line should be extracted, the extraction sites debrided, orthopedic repair performed, and soft tissues sutured. An adhesive tape muzzle can be fabricated to support the jaw while a fibrous union is formed. Partial mandibulectomy is performed in the case of pathologic jaw fracture if jaw salvaging techniques are not available or successful. Oronasal Communication An acute oronasal fistula is present when the nasal cavity is penetrated during extraction of maxillary teeth. This can effectively be treated by raising a buccal-based mucoperiosteal flap to close the extraction site. A chronic oronasal fistula (typically in the area of a lost or extracted maxillary canine tooth) is treated in similar fashion, with epithelium lining the fistula on the palatal side being removed to allow for proper healing of the flap. Trauma from Opposing Teeth When a maxillary canine tooth is extracted in cats, the upper lip may no longer be held out of the path of the opposing mandibular canine tooth which may pinched, puncture or lacerate the upper lip upon closing the mouth. This can be solved by coronal reduction, orthodontic movement or extraction of the mandibular canine. Tongue Hanging out of Mouth It has been reported that the tongue may not be held in the mouth at all times when mandibular canine teeth are extracted in dogs. In the author's opinion, this is rarely the case and more likely associated after partial or complete mandibulectomy procedures. Emphysema and Air Embolism Emphysema may occur after tooth sectioning or alveolectomy with air-driven high-speed equipment or when air or air/water spray is blown into submucosal tissues. Gentle digital pressure applied to the sutured flap will help evacuate air bubbles. Blowing air or air/water spray into alveolar sockets or onto bleeding tissue surfaces is risks the development of air emboli. Local and Systemic Infection Tension on suture lines can lead to wound deshiscence which can be treated by means of resuturing, or the wound is left to granulate and epithelialize. Excessive trauma during the extraction procedure can result in` loss of blood supply to the alveolar bone. Alveolar osteitis is rare in cats and dogs, but it may also develop when the blood clot in the alveolus dislodges and the bone becomes exposed to the oral environment in non-sutured extraction sites. Sequestered bone is then removed, and the alveolus is curetted until healthy bleeding bone is reached. The wound is sutured closed over a newly-formed blood clot with a healthy soft tissue flap. If an extraction site is not healing for longer than one week, a biopsy should be performed to rule out the presence of neoplasia. Bacteremia has been reported during and after ultrasonic teeth cleaning and tooth extraction. However, perioperative use of systemic antibiotics is only warranted in selected cases (e.g., debilitated and immunocompromised patients; patients with organ disease, endocrine disorders, cardiovascular disease, severely contaminated wounds and systemic infections; and patients having permanent implants and transplants). Tooth extraction causing systemic infection is rarely reported.

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Wednesday, March 3, 2010 Thursday, March 4, 2010 Philadelphia, Pennsylvania

COMPANION ANIMAL: Dentistry and Oral Surgery

DEALING WITH FRACTURED FACES

Alexander M. Reiter, Dipl. Tzt., Dr. med. vet., DAVDC, EVDC

Assistant Professor & Chief, Dentistry and Oral Surgery Service ­ Matthew J. Ryan Veterinary Hospital University of Pennsylvania, School of Veterinary Medicine Philadelphia, PA

INTRODUCTION

Prior to surgical repair of any damaged hard and soft tissues, the aim of treatment for head trauma should focus on (1) stabilizing the cardiovascular and respiratory systems to obtain optimal blood pressure and oxygenation, and (2) preventing or limiting secondary brain injury such as cerebral edema or ischemia.

ANATOMY

The mandible and maxilla differ from the rest of the skeleton in that they contain teeth. Dental roots occupy most of the dorsal two-thirds of the mandibular body. In small-breed dogs and some larger dogs, the tooth roots may reach into the ventral mandibular cortex. The ventral third of the mandible includes the mandibular canal, which contains the mandibular artery and vein and the inferior alveolar nerve. In the upper jaw, the incisive bone and the maxilla contain all the teeth, and the infraorbital canal (containing the infraorbital artery, vein and nerve) penetrates the maxillary bone in the area of the fourth premolar and molar teeth.

TRAUMATIC VERSUS PATHOLOGIC JAW FRACTURE

Traumatic jaw fractures are secondary to automobile trauma, falls, kicks, hits, gunshots, and fights with other animals. Pathologic jaw fractures are secondary to periodontal disease, oral neoplasia, and metabolic abnormalities (e.g., hyperparathyroidism). While metabolic disease (`rubber jaw') may have accounted for a higher number of pathologic jaw fracture in the past, the introduction of well-balanced commercial pet diets now makes the development of nutritional secondary hyperparathyroidism a rare occasion.

LOCATION OF JAW FRACTURES

Common sites for mandibular fracture in dogs include the region of the mandibular molars (particularly at distal roots of mandibular first molars) and the area immediately distal to the mandibular canines. In cats, the mandibular symphysis (symphyseal separation and perisymphyseal fracture) and the condylar process of the ramus are frequently involved. A bilateral rostral mandibular fracture is sometimes seen with trauma that led animals fall and land on their chin. A common injury of the upper jaw is a unilateral separating fracture of the maxillary process (a fracture across the maxilla at the level of the canine tooth and premolar teeth), so that the anterior portion of the upper jaw is highly mobile. Some cats with head trauma present with traumatic cleft palate or a unilateral separation of the temporal bone from the parietal bone.

DIAGNOSTIC TOOLS

Following stabilization of life-threatening injuries, jaw fractures can be evaluated under sedation or general anesthesia. The mandibular and maxillofacial bones and the temporomandibular joints (TMJs) are palpated both extraorally and intraorally for asymmetry and discontinuity, and the oral cavity is inspected for mucosal lacerations, fractured and displaced teeth, and (submucosal) hemorrhage. Oral and maxillofacial injuries may include tooth fractures, tooth luxations and avulsions, fractures of the mandibular, maxillary, palatal, nasal, frontal, zygomatic, temporal and other bones of the skull, oronasal defects, TMJ dislocations, lip avulsions, and various other soft tissue injuries. Dental radiographs should always be taken to assess tooth injuries and further define jaw fracture sites. Standard medical radiographs are often an insensitive diagnostic tool in major head trauma patients. Most mandibular and maxillary fractures can be satisfactorily assessed with size 2 and 4 dental radiographic film and intra-oral imaging technique. Dental radiography is quicker (a) in obtaining appropriate and diagnostic views and (b) in producing an image of higher quality and detail, compared to standard medical radiography. The largest dental radiographic film can also be utilized to evaluate

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injuries to the zygomatic arch, mandibular ramus, TMJ and tympanic bulla in the cat and smaller dog. Standard medical radiography and other imaging techniques should be considered for caudal mandibular and maxillary fractures in mediumsized and larger dogs. When radiographs do not provide enough detail, computed tomography (CT) and magnetic resonance imaging (MRI) may be necessary. CT is indicated for caudal mandibular and maxillary fractures and TMJ injury that cannot be assessed adequately with dental or standard medical radiography. CT scanning is preferred over MRI for imaging bone and identifying areas of acute hemorrhage or edema. Imaging studies of the intracranial structures should be considered in any patient with moderate to severe head trauma on presentation, failure of improvement, or deterioration of clinical signs.

MANDIBULAR FRACTURES

Unilateral mandibular fractures may result in the jaw to be deviated toward the side of injury or cause other malocclusion. Bilateral mandibular fractures may result in a dropped-lower-jaw appearance. An oblique mandibular body fracture, with the fracture line running in a rostroventral direction, is relatively stable, as the masticatory muscle forces will hold the fracture segments in apposition to a large extent (favorable fracture). On the other hand, a mandibular body fracture with the fracture line running in a caudoventral direction is unstable, as the muscular forces will lead to considerable displacement of the fracture segments (unfavorable fracture). Fractures of the mandibular ramus are relatively stable because the surrounding muscle mass usually prevents gross displacement of the fracture segments. Condylar process fractures may occur after hit-by-car trauma or falling from a height. Although they often heal as pain-free and functional nonunion, comminuted fractures could result in TMJ ankylosis and inability to open the mouth adequately which is a common post-traumatic complication in immature and young adult cats. The prognosis after corrective condylectomy is guarded to poor if the animal is very young, as the cut bony surfaces are inclined to reankylose.

MAXILLARY FRACTURES

Fractures of the upper jaw are often multiple. The may remain in alignment, or they may be depressed. Epistaxis, facial swelling (edema), pain, and asymmetry are the usual physical findings, with or without crepitus and subcutaneous emphysema. Fractures of the incisive, nasal, maxillary, and palatal bones and the bones that form the zygomatic arch (zygomatic and temporal bones) may often not be severely displaced and do not require surgical repair other than suturing of torn soft tissues. The soft tissues that surround the bone fragments provide support, and healing usually proceeds without complication. When soft tissue attachments are destroyed during overzealous attempts to reduce the fractures, this biologic support is lost. Sometimes, fractures of the temporal bone or a separation of the temporal bone from the parietal bone may go unnoticed in cats with hit-by-car or high-rise trauma. Combined fractures of the zygomatic arch and the mandibular ramus can result in excess callus formation and ankylotic fusion in young animals, resulting in decreased range of TMJ motion. Severely comminuted, depressed, and grossly unstable upper jaw fractures require surgical intervention. Airway obstruction caused by maxillofacial trauma (displaced bones, swelling, or blood) may be life-threatening in brachycephalic dogs and those that have pre-existing respiratory problems. It is recommended that such animals be placed in an oxygen cage; the nostrils should be cleaned off dried blood and discharge and kept unobstructed.

TEETH IN JAW FRACTURE LINES

The relationship of teeth to fracture lines must be determined. Jaw fracture stabilization and postoperative occlusion are unfavorably influenced by extraction of structurally intact teeth associated with fracture lines. Instead, these teeth contribute to proper alignment of fracture segments and provide surface areas for anchorage of fracture repair devices. Extraction of a tooth entails further trauma to and weakening of the bone tissue and also presents technical difficulties when the bone fragments are highly mobile. Results of human studies suggest that the complication rate with regard to fracture healing is not necessarily lower following extraction of teeth located in fracture lines, and teeth should be retained unless there is an absolute indication for removal.

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Teeth adjacent to fracture lines or considered for anchorage of repair devices should be evaluated for the presence of periodontal and endodontic disease. Healthy teeth can be retained, however, it should be noted that teeth with fracture lines extending along the periodontal ligament towards the root apex have the poorest long-term prognosis. Such teeth should be carefully monitored for any evidence of periodontal or endodontic pathology, and appropriate treatment must be instituted as soon as either is recognized. Severely mobile teeth, teeth with advanced periodontitis or periapical disease, and those that interfere with reduction of the jaw fracture should be extracted, as they may inhibit bone healing. Alternatively, hemisection of the tooth and extraction of the crown-root segment in the fracture line can be performed, and the retained crown-root segment must then be treated endodontically. If crown-root segments with adequate bone support can be retained, they may also aid as anchorage structures for interdental wiring and provide surface areas for intra-oral resin splints.

PATIENT PREPARATION

Endotracheal intubation through a pharyngostomy or tracheostomy opening allows intraoperative evaluation of the occlusion, particularly when comminuted fractures are present at several sites of the upper and lower jaw. A temporary tracheostomy may also be useful during postoperative recovery of an animal with airway obstruction. Pre-, intra- and postoperative monitoring of the head trauma patient should emphasize blood pressure, oxygenation and ventilation, and serial neurologic evaluation. Initially, the mouth is flushed with dilute chlorhexidine solution, and the fracture sites are carefully debrided to remove blood clots, food particles, foreign material and necrotic tissue. Bone fragments that could contribute to the stability of fracture repair should be retained. Soft tissue lacerations are then sutured or be closed after orthopedic repair. Most mandibular and some maxillary fractures are open to the oral cavity, and bacterial contamination is inevitable. Antibiotic therapy may be considered in selected cases to prevent infection.

TECHNIQUES OF JAW FRACTURE REPAIR

Maxillomandibular Fixation Tape muzzles can be used in minimally displaced fractures, in young animals with rapid bone healing, pathologic mandibular fractures, and as a means of additional support in cases where other fixation techniques did not achieve optimal stabilization. Muzzling can be temporary first-aid treatment when patient stabilization is necessary before surgical intervention. Proper occlusal alignment and stabilization of caudal mandibular fractures, pathologic mandibular body fractures or chronic temporomandibular joint luxation may also be achieved with a bilateral bis-acryl composite bridge that bonds maxillary and mandibular canines together. When fabricating the muzzles and bridges, the mouth is kept open slightly (5 to 10 mm in cats and small dogs and up to 20 mm in larger dogs) to permit the tongue to protrude and allow prehension of water and food. Circumferential Wiring This is usually performed for treatment of mandibular symphyseal separation or parasymphyseal fractures, which are common injuries in cats with high-rise or hit-by-car trauma. A stab incision is made at the ventral midline in the chin area. A large needle is inserted between bone and soft tissues of the mandible distal to the canines, through which a wire is passed. The needle is then reinserted on the other side and the oral wire end passed through the needle. The needle is removed, and while the symphysis is stabilized in proper alignment, the wire ends are twisted until the lower jaw is stable. The wire is trimmed and bent caudally, so that the skin covers it. The wire should be removed in 4 weeks. Leaving it in place for longer or overtightening it bears the risk of bone and soft tissue necrosis and exposure of canine tooth roots. Interdental Wiring and Intraoral Splinting Interdental wiring should be performed prior to splint application. The Stout multiple loop or modified Risdon wiring techniques make use of the gingiva and dental crowns as anchoring points to stabilize and align fracture segments and to provide additional retention surface for splint materials. Wiring should include at least two teeth of each fracture segment. Intraoral splints made of bis-acryl composite are ideal for the repair of jaw fractures where teeth are present for anchorage of the device. The splint material is applied primarily to the lingual surface of mandibular teeth and the buccal surface of maxillary teeth. The teeth are cleaned and polished with pumice, then dried with an air syringe and acid etched with 40% phosphoric acid gel. Self-curing bis-acryl composite is applied to the teeth via an applicator gun. Once the material has set, the splint is trimmed and polished. The splint is removed by interdental sectioning with a bur and removing the material in

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segments, using an extraction forceps in a shearing motion. The teeth are then cleaned and polished. Gingival inflammation from splint and wire trauma usually subsides within a few days. Osseous Wiring This can be used alone or in combination with interdental wiring and intraoral splint application. After reflection of mucoperiosteal flaps on buccal and lingual bone surfaces, holes are drilled through the mandible no closer than 3 mm to the fracture line, carefully avoiding tooth roots. Two wires are usually used in a triangular configuration where two holes are made in the caudal fracture segment and one (or two) in the rostral segment. Once tightened, the wire ends are bent to lie flat against the bone surface, and the mucoperiosteal flaps are repositioned over the wire ends. In young animals, the wires often become entirely incorporated in the bone and may not need to be removed. Percutaneous (External) Skeletal Fixation This is useful in fractures associated with extensive soft tissue injuries, severe comminution, and edentulous or missing bone segments. At least two Kirschner wires or small Steinmann pins are placed into each fracture segment. Plastic tubing is placed over the external wire/pin ends, and while normal occlusion is maintained with the jaws closed, the tube is filled with self-curing acrylic or custom tray material. To remove the device, the wires/pins are cut close to the acrylic bar with pin cutters and then pulled from the bone. The wires/pins should only engage in one mandible, not cross the intermandibular space and avoid trauma to tooth roots. Bone Plating Mini-, intermediate, and microplates allow placement close to the alveolar margin. The screws may be angled to avoid impingement on tooth roots. Specialized equipment is required, and significant soft tissue elevation is necessary for the placement of these plates, which may compromise the blood supply to the fractured bone segments (particularly when advanced periodontitis has already resulted in loss of bone). Proper occlusion is to be maintained, and trauma to tooth roots must be avoided. Return to normal function is rapid, and healing occurs with little or no callus formation. Partial Mandibulectomy and Maxillectomy Bilateral pathologic mandibular body fractures are a severe complication of advanced periodontal disease in geriatric, small-breed dogs, most commonly occurring in the area of the first mandibular molars or distal to canine teeth following minimal bony stress. Salvage procedures involve extraction of all diseased teeth and partial rostral or central mandibulectomies with bilateral advancement of the lip commissures (commissuroplasty).

POSTOPERATIVE CARE AND POSSIBLE COMPLICATIONS

The occlusion should be assessed and radiographs obtained prior to extubation. Further postoperative management includes control of pain, home oral hygiene (antimicrobials, tooth/splint brushing), restraining devices (Elizabethan collar, muzzles), and a soft food diet for several weeks. Fracture repair devices are removed following radiographic confirmation of fracture healing, usually 3 (young animals) to 6 weeks postoperatively. In general, affected jaws and teeth should be reevaluated in 6 months to determine appropriate healing and whether further dental treatment is required. Postoperative complications associated with the management of jaw fractures include early loss of fracture devices, malocclusion, wound dehiscence, osteomyelitis, bone sequestration, delayed union, nonunion, oronasal fistula, and various forms of dental abnormalities and facial deformities in the growing animal. Proper surgical technique, adequate pain control, and an Elizabethan collar may prevent the loss of fracture devices. Treatment options for postoperative malocclusion include immediate removal of the fixation device, followed by proper reduction. Small occlusal discrepancies after device removal can be corrected by odontoplasty; if malocclusion is severe and prevents closure of the mouth, extraction of one or more teeth will be necessary to restore acceptable masticatory function. Although selective extraction of maloccluding teeth can permit the patient to close the mouth in an inadequately reduced jaw fracture, it is considered a significant compromise for poor surgical technique. Bone fragments impacted into the nasal cavity and diseased teeth in the fracture site could predispose to osteomyelitis and bone sequestration, which may be associated with delayed healing or nonunion. Teeth in jaw fracture lines should be monitored for periodontal and endodontic complications. Severe jaw fractures in puppies can disturb normal skeletal growth and development of the teeth, resulting in facial deformities and dental abnormalities in the growing animal.

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COMPANION ANIMAL: Dentistry and Oral Surgery

PRACTICAL APPROACH TO ORAL TUMORS

Alexander M. Reiter, Dipl. Tzt., Dr. med. vet., DAVDC, EVDC

Assistant Professor & Chief, Dentistry and Oral Surgery Service ­ Matthew J. Ryan Veterinary Hospital University of Pennsylvania, School of Veterinary Medicine Philadelphia, PA

INTRODUCTION

Oral tumors are common in cats and dogs. They may be of dental (odontogenic) or non-dental origin. In dogs, peripheral odontogenic fibroma, acanthomatous ameloblastoma, malignant melanoma, squamous cell carcinoma and fibrosarcoma are most commonly diagnosed in the mouth. In cats, the predominant oral tumors are squamous cell carcinoma and fibrosarcoma. Geriatric patients are generally predisposed to oral tumors, but there are certain tumors (e.g., fibrosarcoma) that occur more frequently in young, large-breed dogs. Papillary squamous cell carcinoma, viral papillomatosis and undifferentiated malignancies are also more likely to occur in young dogs. Male dogs may be at higher risk for malignant melanoma and fibrosarcoma. Large breed dogs have a higher incidence of fibrosarcoma and nontonsillar squamous cell carcinoma, while small breeds have a higher incidence of malignant melanoma and tonsillar squamous cell carcinoma. Dogs with heavily pigmented oral mucosa are often predisposed to malignant melanoma.

BENIGN LESIONS

Enlargement of the gingiva is often due to gingival hyperplasia (an increase in the number of normal cells in a normal arrangement) and may result from chronic or acute inflammatory disease. Gingival enlargement is also caused after administration of anticonvulsants, cyclosporine and calcium channel blockers. Gingivectomy and gingivoplasty are performed to remove excess gingiva. A periapical cyst can develop when scattered epithelial cells within the periodontal ligament proliferate after chronic irritation of the apical periodontal ligament from pulpitis or pulp necrosis. If such a tooth is extracted without removing the cyst lining around the root apex, a residual cyst remains. Similarly an apical (tooth root) abscess can develop when pulp infection and inflammation spread through the apical foramina into the periapical tissues. Treatment is tooth extraction or root canal therapy. The epithelial lining of a dentigerous (tooth containing) cyst around the crowns of unerupted teeth may in some cases undergo neoplastic metaplasia. Therefore, unerupted teeth should be extracted utilizing an open extraction technique, and any epithelial cyst lining should be removed and submitted for histopathological examination. Papillomas are viral-induced and cauliflower-like whitish lesions at mucous membranes and mucocutaneous junctions of the mouth. They occur in dogs less than one year of age and often resolve spontaneously in 1-3 months (unless the patient is immunocompromised). Peripheral odontogenic fibromas are mixed odontogenic tumors and are often located in the gingiva near incisor, canine or premolar teeth. The ossifying type (previously called ossifying epulis) is distinguished from the fibromatous type (previously called fibromatous epulis) by containing varying amounts of bone or dental hard tissue within the tumor's soft tissue. These tumors are excised together with extraction of the involved tooth and thorough curettage of its alveolus. Ameloblastomas are epithelial odontogenic tumors. The canine acanthomatous ameloblastoma (previously called acanthomatous epulis) is a locally invasive tumor causing bone lysis around tooth roots and cystic changes. However, it does not metastasize and is therefore considered to be benign. It often has a rough cauliflower-like surface and may sometimes be similar in appearance to a squamous cell carcinoma. It occurs most commonly in the incisor and canine tooth area of the lower or upper jaw, and less commonly in the carnassial tooth area of the lower or upper jaw. Treatment is mandibulectomy and maxillectomy.

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Odontomas are not true neoplasms but a conglomerate of disorganized, normal tissue cells. Enamel, dentin, cementum, and small tooth-like structures may compose the mass. Lesions with characteristics resembling normal teeth are considered compound odontomas, whereas complex odontomas have a more disorganized arrangement. Other benign oral tumors that are less common include the inductive fibroameloblastoma (cats only), amyloid-producing odontogenic tumor, osteoma, and lipoma.

MALIGNANT LESIONS

Malignant melanoma usually occurs in older dogs with oral pigmentation, but it is very rare in cats. The tumor is pigmented or nonpigmented (amelanotic), often grows rapidly and invades bone early. The tumor surface usually is ulcerated and foulsmelling because of necrosis caused by the lesion outgrowing its blood supply. Typical locations are the gingiva, palate, dorsal surface of the tongue, and mucosal surface and mucocutaneous junctions of the lips and cheeks. Regional and distant metastasis is common at the time of diagnosis. Nontonsillar squamous cell carcinoma typically is a disease of older cats and dogs, but papillary quamous cell carcinoma has been described in adolescent and young adult dogs. The tumors most often are found on the gingiva as proliferative and ulcerated lesions and less often on the mucosa of the lips, cheeks, tongue and sublingual area. Bone invasion is common for gingival lesions. If occurring on the upper jaw in cats, the tumor may be less protuberant, while bone invasion is more severe (into the caudal maxilla, orbit, and zygomatic arch). Metastasis to regional lymph nodes is common, while distant metastasis may occur late in the disease process. Tonsillar squamous cell carcinoma in dogs is highly metastatic. Fibrosarcomas tend to occur in young adult to mid-aged large breed dogs and older smaller dogs. They affect the gingiva, lip/cheek mucosa, or the hard and soft palate and often appear as protuberant, ulcerated lesions. They may occasionally arise from the lateral surface of the incisive bone and maxilla, presenting a slowly enlarging firm mass at the muzzle. Fibrosarcomas are highly invasive. Regional and distant metastasis is less common compared to malignant melanoma and squamous cell carcinoma. Low-grade fibrosarcomas appear benign clinically but are malignant biologically. Peripheral nerve sheath tumors are sometimes misdiagnosed as fibrosarcoma. Osteosarcoma affects the mandible and, less often, the maxilla, often manifesting as an ulcerative or necrotic oral mass with extensive radiographic evidence of bone invasion. Regional and distant metastasis seems to be less common than for limb osteosarcoma. Multilobular tumor of bone is a variant of osteosarcoma, affecting the maxilla, palate, ramus of the mandible, zygomatic arch, and calvarium. Other less common, malignant lesions include hemangiopericytoma, lymophosarcoma, plasma cell tumor, mast cell tumor, and undifferentiated tumors.

ORAL BIOPSY

Proliferative masses, bone swellings and those that cause bone lysis, mucosal lesions suspicious of neoplasia or autoimmune disease, and unilateral oral inflammation/ulceration should be sampled for examination. A biopsy is preferably obtained from an area that can be included in the definitive resection. Areas of necrotic tissue may be present in rapidly growing tumors, and viable tissue should be included in the biopsy sample. A mucosal flap could be raised to access deeper tissue for tumors that are covered by a layer of variably-thick normal tissue. If cytological or histological results do not match the clinical findings, a second, deeper, and larger specimen is obtained. The TNM (tumor, node, metastasis) system aids in describing the clinical extent (staging) of neoplastic disease through evaluation of the primary tumor, regional lymph nodes, and distant sites of possible metastasis. Parotid, mandibular, and medial and lateral retropharyngeal lymph nodes should preferably be evaluated histologically. A negative lymph node biopsy does not preclude the possibility of regional metastasis, which may occur along perineural or vascular routes, or metastasis to other less accessible lymph nodes. Cytological sampling can be performed in the awake or sedated patient and includes the following techniques: · Fine-needle techniques · Impression smears · Scrapings Fine-needle techniques are useful for lesions that exfoliate well and are often performed with a 22-gauge needle by means of a needle biopsy (`woodpecker method') or needle aspiration. Cytological examination of lymph node needle biopsies and

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aspirates may be adequate for diagnosing metastatic melanoma and squamous cell carcinoma but is less satisfactory for other oral tumors. Impression smears and scrapings obtained from the surface of an epithelialized or ulcerated tumor have no diagnostic value. Impression smears and scrapings may be of much greater value if obtained from the cut surface of a tumor. Histological sampling requires general anesthesia and microscopic examination of a formalin-fixed specimen. This is more accurate than cytological sampling. Histological sampling includes the following techniques: · · · · · Grab sampling instruments (Alligator forceps, Rongeurs) Core sampling instruments (for example utilized for bony swellings or lymph nodes) Disposable punch biopsy instruments (open-ended skin biopsy punches) Incisional biopsy (obtain a wedge of tissue using a scalpel blade) Excisional biopsy (may be curative as well as diagnostic; smaller masses and lymph nodes)

Tissue damaging instrumentation must not be used during the sampling procedure so that a diagnosis is not obscured. Multiple samples should be obtained. Hemostasis is achieved by digital pressure, and biopsy sites of more deeply-invading tumors are sutured. For adequate fixation, the specimen is placed in 10% buffered formalin at one part tissue to 10 parts fixative.

TREATMENT

Conservative resection should be restricted to gingival hyperplasia and viral papillomas. Peripheral odontogenic fibromas are removed together with the tooth (which is extracted) and its periodontium (which is curetted) from which they arise. Invasive tumors require radical resective surgery (mandibulectomy, maxillectomy, glossectomy, lip and cheek resection) to provide a cure. Combined therapy (surgery plus radiotherapy and/or chemotherapy) may be indicated, particularly for tumors with local or distant metastasis. The treatment of choice for most oral and maxillofacial tumors is wide surgical excision. Large portions of upper and lower jaws and associated soft tissues can be removed without compromise of quality of life. Preoperative workup includes routine blood tests, blood type determination and cross-matching, coagulation profiles, buccal mucosa bleeding time, regional lymph node aspirates, and diagnostic imaging (thoracic radiographs, abdominal ultrasound, head computed tomography). The client must be informed about intra- and postoperative complications, follow-up care, long-term function and quality of life, and prognosis. The practical limits for maxillectomy range from partial resection of the rostral upper jaw on one or both sides (rostral maxillectomy), a central or caudal portion of the maxilla (central or caudal maxillectomy), the entire dental arcade on one side including the palate to the midline (total maxillectomy) to the entire palate and both entire dental arcades. For more caudally located lesions that extend onto the side of the face, the bones forming the ventral and lateral limits of the orbit can be resected (partial orbitectomy). In cats the relatively small size of the skull and the short, tighter upper lip compared with that of dogs make radical maxillectomy far more challenging. The practical limits for resection of the lower jaw range from partial resection of the mandible on one or both sides (unilateral or bilateral rostral mandibulectomy and partial mandibular body resection), one entire mandible (total mandibulectomy) to one entire mandible and a portion of the mandible on the other side. For caudally located lesions the mandibular ramus or a portion of it can be resected by means of a dorsolateral approach through the zygomatic arch and the masseter and temporal muscles. Bilateral rostral mandibulectomy to the level of the first premolars provides good function and esthetics. Bilateral resection caudal to this level results in progressively greater problems with tongue retention, eating and grooming. Resection of the symphysis causes the two remaining mandibular sections to `float,' which is functionally and esthetically acceptable. Resection should include at least 1-2 centimeters of apparently healthy tissue surrounding the tumor. The use of electrocoagulation along the incised mucosal edges that will be sutured is to be avoided. Bone is cut with power instruments (rotating burs; sagittal and oscillating saws) or an osteotome and mallet. It is often safer to `break out' the piece to be resected than to bur or saw through any remaining bony attachments. The wound is closed with a buccal flap that is undermined until it can cover the defect without tension. In the case of maxillectomies, a two-layer closure is preferred, with the first layer apposing connective tissues of the flap and palate, to relieve tension on the epithelial edges.

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Lingual tumors are resected with good results if the resection can be confined to the free rostral or the dorsocaudal portions of the tongue. Clamping the tongue caudal to the excision site with non-crushing forceps greatly aids in control of bleeding. Surgical principles for resection of tumors of the lip and cheek include maintenance of a functional lip commissure so that the mouth can open adequately, separate closure of mucosal and skin incisions, avoidance of parotid and zygomatic salivary gland ducts or ligation of ducts when avoidance is not possible, and cosmetic closure of resulting facial defects by advancing or rotating tissue from the lower lip and side of the face, head or neck. Hemorrhage is controlled by means of digital compression or vessel ligation. Diffuse bleeding may respond to surface application of a mixture of phenylephrine/lidocain. Other hemostatic materials include gelatin sponges, thrombin, and polysaccharide beads. Dilute epinephrine is to be avoided. Unilateral carotid artery ligation is recommended if hemorrhage continues and cannot be controlled. Displacement of a ligature is the most common cause of bleeding in the immediate postoperative period. Hemoclips should not be used to ligate significant vessels due to their tendency to fall off or tear the vessel. After total mandibulectomy the opposite mandible will swing over toward the midline, which may result in the remaining mandibular canine tooth to impinge on the palate when the mouth is closed; to prevent this, the tooth is extracted or its crown surgically reduced. After more involved mandibulectomy procedures, the tongue will lose its ventral support and often hangs out of the mouth, resulting in drooling and chronic dermatitis. This can be partially corrected by rostral advancement of the lip commissure on one or both sides to form a fold that contains the tongue (commissuroplasty). Wound dehiscence 2 to 3 days after surgery usually results from tension on suture lines or compromised vascularity of flaps. Dehiscence of maxillectomy sites carries more serious consequences, as an oronasal defect may develop. Dehisced flaps are resutured after further undermining to eliminate tension. Closure of a chronic oronasal fistula should be performed after complete healing of surrounding soft tissues has occurred. Postoperative pain control is achieved with a combination of intraoperatively given longer-acting local anesthetics, centrally acting opioids, and NSAIDs. Patients undergoing radical resective surgery invariably benefit from placement of a transdermal fentanyl patch plus injectable opioid supplementation until the patch achieves adequate blood levels. Antibiotic treatment is not required after oral and maxillofacial surgeries in the otherwise healthy patient. Broad-spectrum antibiotics are given perioperatively in debilitated and immunosuppressed patients and those suffering from organ disease, endocrine disorders, cardiovascular disease, severely contaminated wounds and systemic infections. Water is offered once the animal has recovered from anesthesia. Soft food is offered 12 to 24 hours after surgery and maintained for about 2 weeks. Dogs usually eat the same or following day; cats may take several days to adapt. Cats may benefit from placement of an esophagostomy tube to ensure proper nutrition and medication during the immediate postoperative period. Chlorhexidine digluconate solution or gel (0.1-0.2%) is administered into the mouth for 2 weeks. Elizabethan collars, tape and nylon muzzles, or other restraining devices may be used in some animals to prevent disruption of the surgical sites. Reexaminations are scheduled at 2 weeks (removal of skin sutures) and at 2, 6, 12, 18, and 24 months postoperatively. Collaboration with an oncologist is helpful after histopathological results return to discuss the need for further treatment (surgery, radiation therapy and/or chemotherapy). Palpation of nonresected lymph nodes (with cytological or histopathological examination of enlarged nodes) and thoracic radiographs should be performed to monitor for regional and distant metastasis.

CONCLUSION

Radical resective surgery often provides a cure in patients with oral and maxillofacial malignancy and is tolerated surprisingly well by dogs and cats. The quality of life provided by maxillectomy and mandibulectomy procedures is excellent. The multiple anesthesia episodes required for radiation therapy and the systemic sickness and multiple office visits required for chemotherapy are avoided. Combined therapy may be indicated, particularly for lesions with regional or distant metastasis.

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VETERINARY TECHNICIAN

SMALL ANIMAL DERMATOLOGY: THE ITCH AND THE SCRATCH

DIAGNOSING AND TREATING BACTERIAL AND YEAST PYODERMA AND OTITIS

Colleen Walters-Pinney, CVT

Nurse Practitioner, Dermatology and Allergy ­ Matthew J. Ryan Veterinary Hospital University of Pennsylvania, School of Veterinary Medicine Philadelphia, PA

Dermatologic complaints are very common primary reasons owners schedule a visit to the veterinarian for their pets. When a pet presents for alopecia (hair loss,) pruritus (itchiness,) crusting lesions, or ear infections, diagnostics and treatment must be carefully considered. When approaching diagnosis and treatment for chronic, ongoing issues or for problems of an acute nature, carefully consider the patient's history. Helpful background information includes age of onset, duration of symptoms, response to previous treatments. Careful diagnosis and treatment of the patient with skin and/or ear infections has complete impact on that patient's response to therapy. Use of diagnostic methods and tools available must be implemented for optimum results to treatment. The antibiotic treatment prescribed must be appropriately dosed by patient's weight and prescribed for the necessary duration of time for complete clinical cure.

DIAGNOSTIC TESTS

Cytology is the most important and useful test for any patient that presents with pruritus or any other signs of inflammation or infection of the skin or ears. The technician and veterinarian can easily perform direct impression smears, and ear cytology for microscopic examination. Cytology can be performed in any veterinary clinic and requires only the standard Diff-Quik-type stain, microscope, and slides found in almost every clinic. DIRECT IMPRESSION SMEARS are useful for determining bacterial, malassezzia, and inflammatory cell population on any moist lesion: papules, pustules, or other crusting or ulcerative lesion. A glass microscope slide is pressed upon the lesion, after gently lifting a crust if necessary. When sampling a pustule, the pustule may be rupured gently with a 25 guage needle before taking the impression. The glass slide is then quickly heat-fixed and processed through Diff-Quik stain. An ACETATE TAPE PREPARATION can be useful for lesions where surface debris maybe too dry to adhere to a glass slide. Tape is processed through the red and purple components of Diff-Quik stain only (the sky blue fixative destickifies the tape, ruining the prep.) The tape will adhere (sticky side down) to a microscope slide, even when wet. EAR CYTOLOGY is performed on any pet presenting for headshaking, scratching, or any other signs of ear pruritus. Erythema (reddened,) or exudative ears may be noticed by the veterinarian or technician without a specific complaint of ear problems, and should have cytology performed as well. Ceruminous debris, exudate, and/or pus are obtained with a cotton swab from each of the ear canals of both ears. Each ear's swab is rolled out very thinly onto a microscope slide. The slide is then heat fixed and processed through Diff-Quik stain. When examining cytology under the microscope, scan first at low power to find an area that has consistently distributed cells. Then, increase magnification to 1000x, using the oil-immersion objective. Numbers of inflammatory cells may be given descriptively (1+ through 4+, for example, or few, significant, many, confluent), or actual average counts-per-field may be used, depending on the clinician's preference. CULTURE AND SUSCEPTIBILITY may be indicated for any patient who has recurrent or non-responsive bacterial infection of the skin or ears. In small animals, this is almost always sent to a microbiology laboratory for processing. When collecting a sample from the skin for culture and susceptibility screening, choose a pustule, draining tract, or sample the exudative skin under a crust. Sampling from the external ear canal is easily performed by carefully inserting a culturette into the vertical ear canal to the point where it meets the horizontal canal.

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It is very important to remember that microbiological culture in no way substitutes for cytology. The skin and ears are fairly messy places, and it is common for labs to report 5 or more bacterial species on a single ear or skin swab. Often these species will have very different antibiotic susceptibilities. The cytology performed at the same time is enormously helpful in identifying the organism truly responsible for the infection, allowing better and more efficient treatment.

TREATMENT OF BACTERIAL PYODERMA

Almost all bacterial pyodermas are caused by Stapholococcus species. Determining the extent of bacterial pyoderma is necessary for successful treatment. In order to appropriately treat, it is important to identify whether the infection is on the surface, superficial or deep. Surface pyoderma describes what is commonly called a hot spot as well as skin fold infections. If caught early, many can be managed with clipping, cleaning, topical antimicrobials and an e-collar. Systemic antibiotics and pain medications are often used as well. Superficial pyoderma involves infection of the epidermis and follicular epithelium. Papules, pustules, and epidermal collarettes are the hallmark of superficial pyoderma, although more exotic lesions are sometimes seen. Superficial pyoderma needs no less than twenty-one days of appropriately dosed antibiotics to ensure resolution. To reduce the chance of antibiotic resistance, it is best to opt for the highest recommended dose. A good starting point, for example, might be 30 mgs/kg of cephalexin every twelve hours at least three weeks. Deep pyoderma involves the dermis and often the subcutaneous layer. Deep pyoderma, also called bacterial furunculosis can appear as draining tracts, nodules, or severe swelling. The presence of bloody exudate, pain, or both is an indication that the pyoderma involves deeper structures. Antibiotics used for superficial pyoderma are often effective for deep pyodermas, but recommended dosing is at least six weeks. It is essential that patients return for repeat cytology and palpation before therapy is discontinued, as incompletely resolved pyoderma can recur rapidly; there is increased risk of resistance as well. Antibiotic treatment is necessary for at least one to two weeks beyond clinical cure. Compared to the treatment of lacerations or respiratory infections, three to six week course of antibiotics may seem extreme. It is important to remember, however, that antibiotics take longer to reach the skin...the epidermis, with its lack of blood supply is particularly hard to target with systemic medications. It is better to medicate a few days longer than necessary than to discontinue treatment too early and have infections recur. The use of topical antimicrobial therapy is a useful adjunct to systemic antibiotics or anti -fungals. Depending upon the severity of infection, shampoo or a leave-on conditioner once or twice weekly is very beneficial.

TREAMENT OF MALASSEZZIA DERMATITIS

Knowing whether or not Malassezzia is present on inflamed skin is necessary to select appropriate treatment. This is determined by direct impression or, more often, acetate tape preparations. Treatment for heavily populated skin includes systemic antifungals like fluconazole or ketoconazole and often topical therapy. The topical therapy of choice is typically miconazole in the form of shampoo, leave-in conditioner, or spray. Medicated wipes are also used for target areas such as interdigital spaces, nail beds or facial folds.

OTITIS

Treatment of ear disease first involves determining the type of infection... Is it bacterial or fungal? Perform cytology keeping in mind that occasional organisms on the slide can be a normal. Once the type (and quantity) of organism in the ear canal is known, treatment can be selected. For strictly Malassezzia otitis a miconazole lotion can be administered twice daily for two to three weeks. There are quite a few products available that are combination medications that include an antibiotic, antifungal and an anti-inflammatory steroid. These are especially useful for multi-organism infections. The anti-inflammatory component helps make the patient more comfortable in addition to reducing swelling and opening up the ear canal for better distribution of medication. Use of an ear cleaner once daily to several times weekly is recommended to clear the canals of ceruminous debris to then allow full surface coverage of the chosen medication.

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Most recurring pyodermas and many recurring ear infections are secondary to an underlying allergy such as environmental or dietary hypersensitivities. If a patient presents repeatedly for bacterial or yeast dermatitis or otitis, possible underlying causes should be investigated. Is this pet returning to the veterinarian because she or he has an underlying environmental or food allergy? Worth considering as well is patient's age, age of onset and clinical presentation. Other conditions such as hypothyroidism, or Cushing's disease can predispose an animal to recurrent skin problems. Consider too, is this patient's pyoderma not resolving because of antimicrobial resistance? For complete and thorough treatment of patient, primary causes of recurrent ear and skin disease must be worked up. In closing there are three things of great importance to remember when treating skin and ear disease. Identify the type of infection. Treat with an appropriate choice, dose and duration of antimicrobials. Know the primary problem and cause of the recurrence.

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Wednesday, March 3, 2010 Thursday, March 4, 2010 Philadelphia, Pennsylvania

VETERINARY TECHNICIAN

ANESTHESIA IN THE CRITICAL PATIENT

Amy Henderson, CVT

Veterinary Technician, Anesthesia ­ Matthew J. Ryan Veterinary Hospital University of Pennsylvania, School of Veterinary Medicine Philadelphia, PA

PRE-ANESTHETIC ASSESSMENT

Anesthetizing the critically ill and emergency patient is a task that should be taken seriously and with caution. A full assessment is vital in order to provide the safest anesthesia possible. During the physical exam the heart should be ausculted for murmurs that may indicate cardiac disease. Pulses should be palpated to assess quality and rate. Any arrhythmias or pulse deficits should be further investigated with an EKG. The lungs should also be ausculted in all fields to determine if there is any pulmonary disease. Harsh lung sounds or crackles may be a result of fluid overload from heart disease. Muffled lung sounds may be an indication of a pneumothorax or hemothorax. The upper airway should be ausculted as well; increased sounds may be a sign of an obstruction. It is important to evaluate the mucus membranes for capillary refill time and color. These parameters can indicate whether the patient is hyperdynmanic, hypovolemic or hypoxic. The patient's neurological status and mentation should be evaluated as well; abnormalities will affect drug choices and must be closely monitored for change. Bloodwork should be evaluated prior to anesthesia and surgery. There are a number of tests that are very helpful and sometimes crucial. However, time, money and availability of lab facilities may be a limiting factor. A complete blood count and chemistry screen provide useful basic information, but acquiring results takes time. Some facilities are able to do in house blood work which can be ideal in these situations. The NOVA and ISTAT machines, for example, measure basic electrolytes, kidney function, and blood gases. Even a minimum data base (packed cell volume, total solids, and glucose and blood urea nitrogen) is helpful when time is of an essence. A list of all medications that have been administered to the patient, either chronically or currently should be compiled, and their side effects considered. Some medications interfere with metabolism of other drugs. Cardiac medications may make it difficult to treat heart rate and hypotension. A fentanyl patch may enhance the effects of other opioids, whereas buprenorphine might interfere.

PATIENT MONITORING

There are several levels of monitoring that can be done depending on staffing and equipment available. First of all, auscultation, pulse palpation, and mucous membrane assessment are essential, since any monitoring equipment can give inaccurate readings due to a multitude of technical factors. An electrocardiogram is vital for identification of arrhythmias. Ideally, one should be placed before any anesthetic drugs are administered, and any abnormalities should be addressed at that time. Blood pressure is very important in all patients and can be measured indirectly with a doppler or an oscillometric device. Direct measurements can be taken via an arterial catheter. The doppler may be used in conjunction with other blood pressure monitors for the audible detection of changes in heart rate, rhythm or pulse pressure. Invasive blood pressure monitoring is the most accurate method and allows instantaneous detection of changes, but requires placement of an arterial catheter. An esophageal stethoscope is a simple way to hear both heart and lung sounds. It is inexpensive and easy to use. When things go wrong it may be the only form of reliable monitoring equipment. The pulse oximeter is also easy to use and relatively inexpensive. It displays pulse rate and hemoglobin saturation. However, this monitor may not work in patients who are shocky, vasoconstricted, or hypothermic. It is important to understand that the amount of oxygen bound to hemoglobin will not change until the dissolved oxygen in the blood is

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significantly reduced. Therefore, blood gas analysis (which measures dissolved oxygen) is a more accurate determination of a patient's ability to oxygenate. A capnograph is another useful piece of equipment although it can be expensive. End tidal carbon dioxide is used to confirm intubation and assess ventilation. Measurements also provide an indication of cardiac output. Another monitor for assessing ventilatory status is the spirometer. It is beneficial to monitor central venous pressure on patients with heart disease, severe renal disease, shock, and hypovolmia. Central venous pressure is a measure of right atrial pressure and circulatory volume. Placement of the catheter does require advanced technical skill. Patient temperature should be monitored, as hypothermia can have severe effects on the cardiovascular, respiratory and nervous systems. In addition, changes in temperature can affect drug binding, electrolyte status and coagulation. The use of an esophageal temperature probe is most reliable, but a regular thermometer may be used orally, rectally, or in the axillary or inguinal regions. Urinary output is a useful component in determination of hydration status, as well as kidney function. However, placement of a urinary catheter may not be feasible or may present an added risk of infection.

STABILIZATION

When a critical patient arrives, the ABCs (airway, breathing, and circulation) should be addressed immediately. Teamwork is essential. As one person maintains the airway and provides oxygen, another can be working on venous access. Large bore catheters are best but can be difficult to place in the face of hypovolemia. Multiple ports will be needed, so double or triple lumen catheters are useful. Additional catheters may be required as well. Fluids should be started as soon as possible, along with synthetic colloids or blood products. Separate ports for the administration of anesthetic drugs, inotropes or vasopressors should also be made available. Any electrolyte abnormalities or arrhythmias should be corrected as much as possible before induction of anesthesia.

INDUCTION

In the critically ill patient, anesthetic drug doses may need to be reduced. Hypovolemia, blood pH, protein level and temperature are some of the factors that increase the effect of anesthetic agents. A pre-med is usually avoided in patients who are very ill so as not to exacerbate respiratory and cardiovascular depression. However, patients that are very painful may be hard to handle and some are aggressive even in this state. It is better to give a premedication than to struggle and cause further stress to the patient. An increased stress level will lead to a release of catecholamines, and thus potentiate arrhythmias. Low doses of an opioid (hydromorphone) with a tranquilizer (midazolam) may be used to smooth the induction process. For induction, a balanced anesthesia method is better for the patient in order to minimize the side effects from using more of one single drug. Pure mu agonist opioids (such as hydromorphone, fentanyl) are good for induction and maintenance, and are ideal for balanced anesthesia. Their advantages are potent analgesia, minimal cardiovascular depression, and they are reversible. Butorphanol is an opioid agonist-antagonist that is good for sedations. It does not cause as much respiratory depression but its analgesic properties are weaker than other opioids. Buprenorphine is a partial agonist on the mu receptor and an antagonist on the kappa receptor; it is good for post op pain management in procedures that are moderately painful. Both buprenorphine and butorphanol are very hard to reverse. These drugs have a strong affinity to opioid receptors and thus may interfere with subsequent use of other opioids (i.e. fentanyl infusion). Benzodiazepines are sparing on the cardiovascular and respiratory systems. They provide effective sedation in most patients but can be unreliable in some cases (i.e. cats). These drugs will help lower doses of other anesthetic agents. They are good for patients with any type of seizure disorder and provide excellent muscle relaxation. Diazepam, a benzodiazepine used clinically, is fat soluble so it should not be given intramuscularly. Alternatively, midazolam is water soluble and is therefore better for intramuscular injection. It has a rapid half life and clearance from the body. Both benzodiazepines are reversible with flumazenil. Alpha 2 agonists produce profound sedation, muscle relaxation and some analgesia. They are not usually recommended for critically ill patients because of their cardiovascular and respiratory side effects. Alpha 2 agonists cause a marked

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bradycardia and decrease in cardiac output. They also cause peripheral vasoconstriction, thus increasing afterload. This triggers the baroreceptor reflex which causes the heart rate to slow even more. In addition, alpha 2 agonists cause coronary vasoconstriction, thereby decreasing the supply of oxygen to the myocardium. Hypoxia and vomiting may be seen after the drug is administered. These affects may be dose dependent. A benefit of using these drugs is their reversibility (with atipamizole). They may be useful in patients with hypertrophic cardiomyopathy because of the decrease in stroke volume; this is still under investigation. Ketamine is a dissociative drug that is often used with critically ill patients as an induction agent. It increases heart rate, cardiac output, and blood pressure. It is usually avoided in patients with hypertrophic cardiomyopathy or other severe heart conditions. Although ketamine may cause a transient apnea, respiratory depression is minimal, making it a good choice for certain types of respiratory cases. Ketamine increases intracranial and intraocular pressure. It should be avoided in patients with a history of seizures, head trauma, brain tumors, or ocular hypertension. It is also best to avoid ketamine in cases with kidney disease: the metabolites are active, and must be excreted by the kidneys. Ketamine is also used in very low doses for analgesia, due to its effect on receptors that act in modulating transmission of pain. Propofol is a hypnotic drug that is very commonly used in both healthy and sick patients. It is an ultra-short acting drug that is used as an induction agent or as a CRI. It causes peripheral vasodilation, myocardial depression and severe respiratory depression. It should be used with caution in patients that are hypovolemic. Assisted ventilation should be provided as necessary. Propofol has brain protective properties, helps lower intracranial pressure and is therefore is a good choice for head trauma and brain tumor cases. Etomidate is a hypnotic which is sparing on myocardial and respiratory function, and therefore a good choice in certain critical patients. Unlike propofol, it does not cause peripheral vasodilation or myocardial depression. Etomidate inhibits steroid production by the adrenals, so caution should be used with Addisonian patients. Acute hemolysis can occur due to its high osmolarity. Gagging or vomiting may occur at induction. Etomidate is a good drug for trauma patients, patients with cardiovascular or hepatic disease, and for compromised animals that need a cesarean section.

MAINTENANCE

Maintenance of critical patients under anesthesia can be performed with inhalants. Usually Isoflurane or Sevoflurane are the best choices. Halothane should be avoided because of the increased risk of arrhythmias in the critical patient. All inhalants cause myocardial depression, respiratory depression and vasodilation and should be used cautiously in critically ill patients. Constant rate infusions of propofol, ketamine, lidocaine (caution with toxicity) and opioids (fentanyl, morphine, methadone, hydromorphine, and butorphanol) can be used in conjunction with inhalants. These infusions will lower the amount of inhalant needed and therefore limit negative cardiovascular side effects. Total intravenous anesthesia can be done with a combination of analgesic, anesthetic, and hypnotic agents.

HYPOTENSION

Hypotension is common in critically ill patients, and is exacerbated by anesthetics. Minimizing inhalant delivery with the use of the CRIs described above is often necessary. The underlying cause of hypotension is often hypovolemia requiring aggressive resuscitation with crystalloids, colloids, and blood products. Serial analysis of blood gases and electrolytes should be performed and treated appropriately. Some patients may require inotropic agents such as dopamine or dobutamine. These infusions can cause hypertension, tachycardia, and arrhythmias, and should therefore be used cautiously.

RECOVERY

During the recovery period, monitoring of heart rate, respiration, temperature and blood pressure should continued. Packed cell volume, plasma protein, and blood glucose should be performed serially as well as electrolytes and blood gases when applicable. Analgesics should be given as needed. The patient should be kept in a dry warm area and recovered to normothermia.

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Drug/Dose Fentanyl Bolus 0.0025-0.005mg/kg intraop infusion0.1-1mcg/kg/min post op infusion- 1-5 mcg/kg/hr Morphine Bolus 0.1-0.5 mg/kg (IV must be diluted) Premed 0.5-2mg/kg (dogs) 0.25-0.5mg/kg (cats) infusion 0.1-0.3mg/kg/hr

Indications analgesia, decrease MAC sedation

Side Effects respiratory depression, bradycardia, decrease gut motility, dysphoria Increased vagal tone respiratory depression, bradycardia, decreased gut motility, dysphoria, histamine release, Urinary retention, vomiting Increased vagal tone respiratory depression bradycardia, decrease gut motility, increase vagal Tone

analgesia, decrease MAC sedation

Methadone Bolus 0.2-0.5mg/kg Premed 0.5-2mg/kg (dogs) 0.1-0.5mg/kg (cats)

analgesia, decrease MAC, inhibit NMDA receptors no vomiting, sedation

Hydromorphone Bolus 0.025-1mg/kg Premed 0.05-0.3mg/kg (dogs) 0.05-0.1mg/kg (cats)

analgesia, decrease MAC sedation

respiratory depression, bradycardia, decrease gut motility, vomiting, increase vagal tone hard to reverse

Buprenorphine Dose 0.007-0.03mg/kg Meperidine Dose 2-4mg/kg never give IV Butorphanol Dose 0.1-0.5mg/kg reversal dose 0.01-0.05mg/kg infusion 0.1-0.5mg/kg/hr Ketamine Dose 1-10mg/kg Infusion 0.05-0.6mg/kg/hr

analgesia

analgesia, Relaxes sphincter tone

histamine release, respiratory depression, bradycardia hard to reverse, decrease effects of mu opioids

mild analgesia, sedation, decrease MAC, less respiratory depression, less vomiting

analgesia, decrease MAC, sedation, inhibits NMDA receptors

not reversible, should be given with muscle relaxer

Propofol Bolus 1-2mg/kg Induction dose 6-8mg/kg (depends on premed) 0.1-0.3 mg/kg/min Etomidate Bolus 0.2mg/kg (dilute with cats & renal failure patients) induction dose 1-2mg/kg

hypnotic, decrease MAC as a CRI, short acting, decrease CMR

vasodilator, decreases contractility, respiratory depression, decrease infusion laryngeal function

hypnotic, cardiac and respiratory sparing.

can induce vomiting, decreases steroid production (should be given with another induction agent to prevent vomiting and excitement

References Available Upon Request

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Wednesday, March 3, 2010 Thursday, March 4, 2010 Philadelphia, Pennsylvania

VETERINARY TECHNICIAN

A TAIL OF TWO KIDNEYS: KEEPING OUR RENAL TRANSPLANT RECIPIENTS INFECTION FREE

Lynne Beale, CVT

Renal Transplant Coordinator & Nurse University of Pennsylvania, School of Veterinary Medicine Philadelphia, PA

INTRODUCTION

Renal transplantation has been a treatment option for cats at the Matthew J. Ryan Veterinary Hospital of the University of Pennsylvania since Dr. Lillian Aronson started the program in 1998. Since the programs inception, the transplant team has performed 125 feline transplants and more recently, three canine transplants have been performed. It is important to recognize that renal transplantation is a treatment option for cats and dogs in decompensated renal failure; in other words those patients that are losing weight and / or becoming anemic and azotemic despite medical management. The transplant team's goal is to provide a good quality of life for a patient that would not otherwise survive. Prior to transplantation, potential candidates will undergo extensive testing to insure their suitability as a potential transplant recipient. Our diligence does not just include the recipient, but also our donors as well. Infectious disease testing is paramount on our list, since our recipients will need to be immunosuppressed for the rest of their lives. One of the biggest challenges in renal transplantation is protecting our immunosuppressed patients from infections before, during, and after renal transplantation.

IMMUNOSUPPRESSION FOR THE RENAL TRANSPLANT RECIPIENT

Organ transplantation is possible because of the discovery of drugs that can suppress the immune system. Without these drugs, the natural immune system would go out on a "seek and destroy" mission to the foreign "invader." Currently in both human and veterinary medicine, the ability to suppress only those parts of our immune system responsible for the attack on an allograft has not yet been achieved. One of the unfortunate aspects of immunosuppression in a recipient of a transplanted organ is the increased susceptibility to infection. A critical, yet unanswered question in transplantation medicine is "how can we manage immunosuppressive therapy to minimize the risk of infection while maximizing protection against rejection of the transplanted kidney?" The identification of an appropriate candidate through a thorough pretransplantation work-up is a good place to start and critical to the ultimate success of the procedure. Current immunouspressive therapy in the veterinary patient includes a combination of the Calcineurin inhibitor, CsA and the glucocorticoid, prednisolone. These drugs are used together for their synergistic effects. Currently, the oral liquid formulation of cyclosporine, Neoral (100mg/ml), is recommended. Cyclosporine is begun 24-96h prior to transplantation. Neoral is administered at a dose of 1-4mg/kg PO q12h depending on the pet's appetite. Ideally, a target 12-hour wholeblood trough concentration of 300 to 500ng/ml is desired prior to surgery. Prednisolone is administered beginning the morning of surgery. At our facility, prednisolone is started at a dose range of 0.5-1mg/kg BID. Once it is established that we have a good candidate and transplantation is performed, we can titrate our immunosupression to suit the needs of patients on an individual basis. While there is no cookie cutter formula for immunosuppression, we can follow certain guidelines and criteria, and then modify and custom tailor it to fit the needs of individual patients. Prior to transplantation, it is important to make sure that our patients can absorb the medication and achieve and maintain an appropriate level of immunosuppression. Once we know this to be true, we can move forward with transplantation. During the first 3-6 months following transplantation, immunouspressive therapy is kept at the higher end of what we call our "therapeutic" reference range to prevent allograft rejection. As a result, this period of time is also when patients are most susceptible to infectious disease. Thorough and more frequent rechecks of our patients during this time are critical in finding that balance between "prevention of infection vs. protection against rejection." During these rechecks, some of the blood work performed includes a cyclosporine level as well as a complete blood count (CBC). The CBC allows us to evaluate our total lymphocyte count which is often low if we are achieving adequate immunosuppression. If the neutrophil count is elevated, this could indicate rejection or evidence of an infection. After the initial post operative period of 3-6 months, we can start feeling a bit more comfortable with tapering some of our immunouspressive medication. Tapering of the medication is tailored to each individual patient and is only started at this point if the patient has been stable and has not experienced an episode of allograft rejection. As we start tapering some of the medication, patients are monitored closely for any trends in blood values out of the "norm" for that particular patient. The transplant team will monitor the recipients for the rest of their life to try to insure that we have achieved that balance needed for success and health of our patient.

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THE PRE-TRANSPLANT WORK-UP

During this phase we are gathering all information needed to make certain our patients do not have any infectious disease that would preclude them from renal transplantation. In every case, tests include; Feline

· · · ·

FeLV FIV Toxoplasma; IgG and IgM Urine Culture

Canine · Lyme / Tick titers · Toxoplasma; IgG and IgM · Urine culture Alternately, if a particular patient exhibits clinical signs or lab work indicates a particular infectious disease, we will expand our testing beyond what we typically test for. It is important to understand that subtle clinical signs or those that appear seemingly benign should never be ignored. Whether it is fungal, viral, bacterial, or parasitic our diagnostics will follow whatever the clinical picture is painting for us. What do we do with these results once we have them? What positive tests truly preclude a potential candidate? Regarding infectious disease the only test that will automatically preclude a patient is having an FeLV positive status. Some transplant surgeons will consider transplanting a cat that is FIV positive, but does not exhibit an active infection. To date, our facility has not transplanted a cat that has been FIV positive. What about Toxoplasma gondii (T gondii)? Because of the increased prevalence of T gondii in this part of the country, all potential donor and recipients currently undergo serologic testing (IgG and IgM) for Toxoplasmosis. T gondii can cause significant morbidity and mortality in both human and veterinary immunocompromised patients. As a matter of policy at our facility, seropositive recipients are placed on lifelong prophylactic Clindamycin (25mg PO q12h) which is started when immunosuppression is initiated. This has been successful at keeping T gondii from reactivating. Trimethoprim-sulpha (15mg/kg PO q12h) has also been used in cats that did not tolerate Clindamycin. Although we no longer use seropositive donors for seronegative recipients, we have successfully used a seropositive donor for a seropositive recipient. To date, of the 125 recipients, 13 recipients with a positive IgG and/or a positive IgM titer have been placed on prophylactic Clindamycin therapy. Two cats are currently alive 425 and 1565 days following transplantation. Nine cats have died a median of 396 days following transplantation. Two cats died >1year following transplantation, but the exact time is unknown. Cause of death included, lymphosarcoma (3 cats), cardiomyopathy (1 cat), presumed antibiotic toxicity (1 cat), FIP (1 cat), systemic Klebsiella pneumonia infection (1 cat), accidental avulsion of the allograft (1 cat), chronic retroperitoneal fibrosis (1 cat), chronic pyelonephritis (1 cat) and allograft failure (1 cat). None of the cats died from an active T gondii infection. Prior to prophylactic treatment, 4 cats died due to a reactivation of the infection. Potential canine donor or recipients should be clear of infectious disease. If the patient demonstrates a positive Lyme or other tick titers, appropriate prophylactic therapy should be inititated if transplantation and immunosupression is going to occur. If a patient has a history of recurring urinary tract infections, or if a positive urine culture is found during the evaluation process, every effort is made to clear the infection prior to transplantation. Antibiotic therapy is continued for 4-6 weeks and then a urine culture performed approximately 3-5 days after the discontinuation of the antibiotic therapy. If the culture is negative, a cyclosporine "challenge" is performed. To perform a challenge, the potential candidate is placed on cyclosporine for ~ 2 weeks, therapeutic levels of immunosupression achieved, and then a urine culture performed mid way and at the conclusion of the challenge. If an infection is identified during or at the conclusion of the challenge, the patient is not considered an appropriate candidate for the procedure.

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DONOR SUITABILITY TESTING - PRE-RENAL DONATION

With regards to our feline donors, there have been a few sources for procuring them. The first which is nearest and dearest to my heart is the York County SPCA. There is an agreement in place between our institutions of adopting young healthy friendly FeLV and FIV negative cats. Once adopted into our program, the cats obtained from this facility are put into quarantine or a settling in period. At the end of this period, the donor cats are screened for infectious disease similar to the testing for the recipients. Although they have been documented as being FeLV and FIV negative, we will repeat those tests here for assurance. Typically these cats have been abandoned or found as a stray, so the history is unknown. We make every effort to learn as much as possible about them prior to using them as a renal donor. As previously mentioned, if a donor cat is found to be T gondii positive, this cat can be used for a T gondii positive recipient. The second source of procuring donor cats is from a laboratory setting where they are bred to be "specific pathogen free" (SPF). A similar infectious disease screen is performed on these cats, but an extended quarantine period that we typically have with our SPCA cats is not necessary. Similar to the recipient population, expanded testing will be performed if necessary. Prior to donation, fecal screening may also be performed to identify patients with Campylobacter. In a cat with a normal immune system, Campylobacter rarely becomes an issue, since most Campylobacter sp are not pathogenic. Since our donors are required to be adopted by the recipient family, and they will be living with an immunosuppressed recipient we will treat and attempt to clear them of this infection prior to them going home with the recipient. Our donors are housed in a semi-private room where we can monitor traffic in and out of the room. Although we cannot completely protect them through full isolation from hospitalized patients, every precaution is taken including appropriate footwear, personal hygiene, handling and husbandry. It is important to note that new cats will not be introduced into the colony until they have been fully screened and cleared of potential dangers to our existing colony. Rotating toys and blankets, as well as only keeping things in the room that can be fully disinfected, is something we can do to maintain an infection free environment.

THE HOSPITALIZED TRANSPLANT RECIPIENT

What can we do to keep them infection free now that they are immunosuppressed? Whether the recipient just received their new kidney, has come back for a recheck, or hospitalized with a complication, a renal transplantation ward exists in the hospital dedicated to housing them. The exception for this would be the immediate 24-72 hour period following the transplant procedure at which time they are monitored in the ICU. Care is taken by our medical staff of nurses, and doctors to use many common sense practices when handling or working with these patients. While we cannot keep our patients in a bubble to protect them, we can certainly surround them with good practices and consistency of care. Since the ICU does not have a separate area dedicated to immunosupressed patients, the doctors and nurses of the ICU are aware of what other patients are in the ICU, and if there are any that could potentially pose a danger to an immunosupressed patient, they can put distance between them. If a nurse is working with a patient that could potentially be a risk to our immunosuppressed patient, they will not assign themselves to the transplant patient. As the renal transplantation nurse, I am available to care for these patients while in any area of the hospital, whether it is assisting the ICU nurses with care, or taking them for follow up to one of the other services such as radiology or cardiology. Consistency and continuity of care is imperative at this particular juncture of their stay. Usually the consistency and continuity will lead to familiarity of the patient with their nurse thus making them more comfortable and relatively stress free. Once in the renal transplant ward, they are typically the only patients hospitalized there and contact with other hospitalized patients is kept to a minimum. Within the ward, there is dedicated equipment strictly used for the recipients. The recipients' cage is usually adorned with cage markers or tags alerting whoever may come in, that this is a patient that is immunosuppressed and to please wear gloves, and minimal handling by medical staff only. Following surgery, the donor cat may be housed in the transplant ward, unless there is concern about a possible infectious disease such as Campylobacter. Handling of the donor cat would be performed by a nurse not working with the recipient. Interaction with cats housed in the donor colony would be minimal or at the end of the days shift, so as not to jeopardize the safety of the immunosuppressed patient. Common sense cleanliness practices, including washing hands before handling, disinfecting any surfaces that could potentially harbor as well as disinfecting litter boxes and cages each day should always be in place,. Additionally, when administering medications, care should be taken whether the medication is given orally, IV, SQ, and IM. "An ounce of prevention is worth a pound of cure."

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GOING HOME ­ RECIPIENT AND DONOR

When both donor and recipient are well and are ready to go home, what is the best way to keep everyone at home safe? Important questions to ask during this process include "how many others pets do you have at home and have other pets in the house been tested for infectious disease?" Sometimes it is taken for granted that although pets have lived in the house harmoniously for years and there has never been a problem, owners now have a pet that is immunosuppressed. We caution owners about where they bring their pets, and not bringing new pets into the house until they have been properly screened. For the initial 4-6 weeks following transplantation, the recipient is restricted to cage rest to allow for proper healing. During this time, the donor can ease their way into new routines and new surroundings. We also caution owners that if one of the other pets in the house is showing any clinical signs of being sick, to make sure to separate the sick pet from the renal recipient. As previously discussed, immunosuppression is at its highest level during the first 3-6mo following transplantation, so every care should be taken to protect our patients, whether it is at home or going back to the hospital for rechecks. Lines of communication are constantly open between our transplant team, the local veterinarian and our recipient families on how to best protect our recipient. For many local veterinary practitioners, this may be their first experience with a renal transplant patient and so it is our responsibility to educate and advise on our general practices and expectations. We ask that they care for our patients and modify their practices if necessary to help keep our patients free of infectious disease.

CONCLUSION

After all the testing is done and precautions taken, it is still impossible to know which pets will do well on immunosuppressive therapy and which ones may develop complications. For all that is known within renal transplantation, there are unknowns as well. To be able to give back the quality of life to a pet, and to hear the owners say "I have not seen him do that in years" or "she has not been this happy in a long time." makes all of the precautions that are taken worth the time and effort. Finding a balance with common sense, proactive care, and an "ounce of prevention" we can go a long way in preventing infection in our immunosuppressed renal transplant recipients. For every miracle of modern medicine we celebrate as a transplant team, the ones that we remember most are the very few who lost their battle and eventually their lives because of infection. This does not discourage us, but only challenges us to work harder to prevent these complications.

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VETERINARY TECHNICIAN

EQUINE COLITIS FROM A NURSING STANDPOINT: PART 1 & 2

Christopher Rizzo, LVT

Veterinary Nurse, New Bolton Center University of Pennsylvania, School of Veterinary Medicine Kennett Square, PA

CAUSES / SYMPTOMS OF COLITIS WHAT IS COLITIS?

Colitis is a general term used to describe any inflammation of the colon. Digestion and absorption occur along the approximate 80 feet of large intestine inside the horse's abdomen. Upon consuming any feed material, smell and taste stimulate the salivary glands in which digestion commences.

HOW DOES THE COLON WORK?

Microbes are imperative to the breakdown of carbohydrates so that they can be absorbed and utilized as energy. The large colon houses the majority of these microbes. The colon collects and stores waste products of digestion. It pushes digesta toward the anus for eventual elimination.

WHAT EXACTLY IS DIARRHEA?

Diarrhea is an excessive amount of water in the manure. For some reason, the colon is not absorbing the appropriate amount of water from the digesta. This happens when something disrupts the normal healthy balance of intestinal flora in the colon. There are numerous reasons why this may occur. Some of these include, Clostridium difficile, Clostridium perfingens, Salmonellosis, antimicrobial associated diarrhea, Potomac Horse Fever, impaction induced colitis, and non steroidal anti-inflammatory drug toxicity. Clostridium difficile and Clostridium perfingens are the two most common anaerobes isolated from the feces of colitis patients. These are normal inhabitants of the gastrointestinal tract and a problem arises when there is an overgrowth of either organism, which is subsequently followed by the production of toxins. Clostridium difficile is an anaerobic bacterium. Essentially it is the toxins produced by these bacteria that cause problems. Clostridium perfingens can produce up to 5 toxins, however toxin A and B are most commonly associated with diarrhea in horses. Salmonellosis is one of the most commonly diagnosed infectious causes of diarrhea in horses. There are over one hundred different species / strains of salmonella. Most horses normally carry at least one species of salmonella in their intestinal tract. They actually contribute to digestion. The amount of salmonella is typically kept at bay due to the normal bacterial flora that is already residing in the gastrointestinal tract. Surgical insult is often blamed for postoperative colitis. This is in fact, rarely true. Most often times, even with minor surgeries, patients who recover without incident can be affected by postoperative colitis. This is typically induced by the antibiotics that are prescribed post surgery. Typically antibiotics are not given to colitis patients unless they are severely leukopenic or neutropenic in which case they are extremely susceptible to infection as their internal defense mechanisms are compromised. The antibiotics can actually cause gastrointestinal upset in an already disturbed floral environment. Metronidazole can be used with Clostridial diarrhea as it has anti inflammatory properties in the colon and Clostridium is susceptible to this antibiotic. NSAID toxicity can occur as a result of the administration of phenylbutazone, flunixin meglumine or ketoprofen. Toxicity can occur at a therapeutic or even sub therapeutic NSAID dosage. Although the pathogenesis is complex, we know that prostaglandin synthesis which in turn disrupts mucosal blood flow and other mechanisms that protect the colonic mucosa. This ultimately leads to severe ulceration, inflammation, and thickening of the bowel wall. The resulting disease process is called right dorsal colitis. NSAID toxicity can also have devastating effects on the kidneys.

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Potomac Horse Fever is an illness that originated around the Potomac River in Maryland in 1979. It has since been recognized throughout the United States as well as other countries. It is caused by the intracellular parasite, Neorickettsia risticii. The organism infects peripheral monocytes and macrophages, and various colonic and small intestine epithelial cells. The PHF organism is found inside trematodes that parasitize water snails. During mid spring when the water becomes warm, the flukes hatch and are ingested by a number of aquatic insects. The horse can then become infected after coming in contact with food or water that has been contaminated by the insects. After consuming the organism, it multiplies in the intestinal tract, where it causes marked inflammation or colitis. This can lead to some of the clinical signs of fever, depression, anorexia, diarrhea, laminitis, or in unusual cases, abortion. Distal limb edema can also occur. Under microscopic observation of a blood smear, the organism can sometimes be found in the monocytes; however PCR testing is more accurate and will determine if the organism's DNA is present in blood or feces. The paired serological antibody titers could also be submitted for IFA or ELISA testing to aid in diagnosis. The drug of choice to treat PHF is oxytetracycline. Doxycycline is also acceptable but can cause GI upset. The oxytetracycline will actually kill the organism Neorickettsia risticii. Patients with PHF are significantly more prone to developing laminitis. Impaction induced colitis can occur when a patient has a large or small colon impaction. The ingesta may obstruct the intestine and cause inflammation around the impaction. The inflammation causes focal protein loss and if it is severe enough, it can cause leukopenia and low-grade fevers. A colitis problem list can include fever, lethargy, leukopenia, dehydration, endotoxemia, tachycardia, tachypnea, discomfort, laminitis, and the most common is diarrhea. Other things to consider when organizing a problem list may include, low grade fever, normal temperature is 99.0º to 101.5ºF, lethargy, leukopenia (usually associated with Salmonella), dehydration, poor skin turger time, prolonged jugular refill time, hemoconcentration or high packed cell volume, and high urine specific gravity.

ADMISSION

Where to start is very important. Assess your patient on the trailer before admission to the hospital. Look inside the horse trailer and see for yourself if there are any loose feces present. Look at the horse's tail and see if there is evidence of diarrhea in the hair. Get a good patient history. Ask if there have been any changes in feed or a new shipment of hay. Ask if the horse has been away from its normal barn for any reason or if he has been treated with any medications. If you are admitting a potential diarrhea case, you should wear personal protective gear. Some items might include disposable gowns, disposable Tyvek ® suits, latex gloves, bonnets, face masks, and protective eye wear. Don't forget protective foot ware such as designated boots or plastic disposable boots to go over your shoes. You do not want to come in contact with this patient and then walk all over the hospital. We place patients in isolation based on if they physically have diarrhea, leukopenia, and an increased rectal temperature. Place ice on feet profalactically. The idea is to constrict blood vessels in the feet in order to prevent the toxins from making their way to the feet and potentially causing laminitis, although this is just one proposed mechanism. Collect admission blood samples. As always, consult with the clinician but typically some things to start out with include a complete blood count, (CBC), chemistry panel, fibrinogen, blood lactate, and venous blood gas. Collect an admission fecal sample if at all possible for a Salmonella polymerase chain reaction (PCR) test. Submit a fecal sample for Clostridium testing. This test will only search for the presence of the toxin in the feces as opposed to the PCR which detects the presence of DNA of the Salmonella. Culture remains the gold standard for Salmonella because the PCR will test for BOTH live and dead DNA.

FLUID THERAPY / MAINTENANCE

Use a number 40 clipper blade and clip the area on the cranial third of the neck in the jugular groove for placement of the intravenous catheter. Aseptically scrub the site from the middle out using sterile water and Betasept® (Chlorhexidine gluconate) and wipe off with alcohol. You should scrub for a minimum of five minutes. You may want to use an intradermal injection of 2% lidocaine if placing the catheter in a neonate. We use long term IV catheters as patients with colitis are prone to thrombophlebitis. Some catheters to consider are a fourteen / sixteen gauge polyurethane over the wire or a seven French double lumen intravenous catheter.

IV FLUIDS

Lactated Ringer's solution, Normosol-R, and Plasmalyte, are the intravenous fluids of choice. Hypertonic saline can be used if hypotensive shock is determined due to sever fluid loss. Fluid resuscitation is imperative on patient arrival. Skin turgor

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test, sunken eyes, packed cell volume and urine specific gravity along with admission blood work are all key indicators of initial hydration. Fluid maintenance dose for an adult horse is 2-4ml per kg per hour but remember to add in percent deficit and ongoing losses when calculating appropriate fluid rate. It is important to be diligent regarding the patient's ins and outs. Be sure to log all IV fluids given along with additives. Do hourly patient checks to insure the fluids are running at target rate. Hanging a urine catcher is also useful in monitoring outs. This is difficult with female patients. If the patient is refluxing, have a log for that and calculate that in with the fluid losses. Compare ins and outs frequently in order to insure you are keeping up and adjust if necessary. Have a log and only designated personnel filling water buckets as this is also considered as a fluid intake. Blousing intravenous fluids may be necessary. It is not ideal to bolus IV fluids that contain additives such as potassium chloride. Check urine specific gravity. The normal USG for an adult horse is 1.025g/dl (Merck). Foals tend to have a lower urine specific gravity as they are on a mostly liquid diet. By monitoring urine specific gravity, it gives a good indicator of hydration and is relatively inexpensive. The normal central venous pressure (CVP) is 8 ­ 10 cm H2O for an adult horse. You can also run a colloid oncotic pressure (COP) which is especially important after giving Hetastarch to determine if appropriate colloidal support has been achieved. Normal range for an adult horse is 18-20.

TREATMENTS AND SUPPORTIVE CARE

ICU check sheets are essential. Patients with diarrhea should have an ICU check done every four to six hours. An ICU check includes such things as a temperature, pulse, respiration check, mucous membrane color, capillary refill time, gastrointestinal motility, abdominal distension, digital pulses, heat in feet, urine output, fecal output, PCV, TS, oral fluid intake. Early detection is the key. Some medications that can be given orally to help combat diarrhea include nasogastric intubation of Bio-SpongeTM powder which absorbs toxins in the gastrointestinal tract. (Use warm water to reconstitute.) Bio-SpongeTM is also available in an oral paste; however it is considerably more expensive. The downside of this is that the patient's mouth gets coated with the medication and they can potentially spit some of it out. If the patient is allowed to eat, they can choose not to. Bismuth subsalicylate (Pepto Bismol TM) suspension can also be given by nasogastric intubation; however it needs to be given in large doses to prove effective. Remember that patients that receive bismuth subsalicylate can produce black tarry feces. Provided the patient is not refluxing, oral fluids by nasogastric intubation are acceptable. Metronidazole can be given per rectum however; it can have neurologic side affects whether given per os, or per rectum. A higher dose is recommended as absorption is less when given per rectum. Flunixin Meglumine (Banamine®) is an NSAID, at a full dose (1.1mg/kg) it has analgesic and anti-inflammatory properties because it interrupts the inflammatory cascade. Low dose Banamine® (0.25 mg/kg q 8) can be administered for its endotoxic properties, but will no longer have anti-inflammatory or analgesic effects. Endotoxin is the lipopolysaccharide (LPS) that is part of the gram negative cell wall. The endotoxin is released into the GI tract when the bacteria either rapidly die or multiply. It is the job of the liver to filter out toxins and sometimes with a disruption of the intestine, these bacteria can build up. Horses are VERY sensitive to LPS. In colitis, the colonic wall becomes inflamed and "leaky" therefore allowing translocation of gram negative bacteria from the gastrointestinal lumen into the systemic circulation. Hetastarch is a synthetic colloid. Albumin is the main protein in the blood. When the albumin concentration gets low, fluid can leak out of the vasculature, which can lead to hypovolemia and peripheral edema. Replacement of albumin via plasma administration is ideal, however typically not achievable in the adult horse, as you need to give very large volumes of plasma to replace protein. Therefore a synthetic colloid such as Hetastarch is utilized to increase the colloidal oncotic pressure in the vasculature; thus keeping fluid in the blood vessels.

ANTIENDOTOXIC THERAPY

How does plasma help? While plasma can offer colloidal support in large volumes, it is used most frequently for its antiendotoxic effects. Most varieties of plasma are hyperimmunized and therefore contain antibodies which help to fight infection and endotoxemia. When administering hyperimmunized plasma, you should take an initial rectal temperature, heart rate and respiratory rate. Hang the plasma and begin at a very slow drip rate. After five minutes recheck the TPR to ensure that nothing has increased. If the TPR remains stable slowly increase the drip rate. Continue to check the TPR every

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five minutes for at least 30 minutes and steadily increase the drip rate until desired target rate is acquired. Along with TPR, monitor for signs of reaction such as hives, sweating, facial edema, tachycardia, or fever

POLYMYXIN B ­ ANTIENDOTOXIC AGENTS

Polymyxin B is an antibiotic, which is used at sub-antibiotic doses due to nephrotoxicity. It binds LPS and therefore acts as an anti endotoxic agent.

PATIENT COMFORT AND CARE

As nurses one of our most important duties is patient care and comfort. We do whatever we can to keep the patient as comfortable as possible when they are sick. A key point when dealing with diarrhea is proper hygiene. One of the first things to do is make sure the horse's tail is clean. If it isn't, wash it and dry it. Then place a braid in the tail and cover it with a rectal sleeve or long plastic bag, attaching it to the patient with elastikon or white tape. Poke a few small holes in the bag to allow it to breathe. That takes care of the feces getting in the tail. This bag / braid should be changed at least once per day. Depending if the patient has distal limb edema, leg wraps might be warranted. In this case, again make sure the legs are clean and then apply standing wraps as you would normally and then tape some plastic bags or cling wrap to the outside of them. This will prevent a large amount of diarrhea from soaking into the wraps. It is also very important to keep the hind quarters and perineum clean. It is uncomfortable for the patient to have wet fecal material running down their legs and tail. This is even more important when dealing with foals since their skin is even more sensitive than that of an adult horse. Washing the tail and hindquarters may be necessary up to every two to four hours. There are also some commercially available ointments that can be applied to scalded and uncomfortable skin. They are Flanders butt cream, perineal foam, and Desetin®.

PREVENTION / MANAGEMENT OF LAMANITIS

Laminitis is a very painful condition that causes the sensitive lamina to separate from the dorsal hoof wall insensitive lamina, which can cause rotation and or sinking of the coffin bone. Some steps we take to avoid / minimize this occurrence are to check for an increase in digital pulses, monitor soundness in the stall, and check for heat in the feet. Very often, when a patient is admitted to the hospital with the clinical signs of colitis, we will take initial lateral projection radiographs as a baseline in order to have something to compare to in the event that laminitis occurs. If signs of laminitis are present, some ways to minimize or to slow the process are, to ice the feet, remove shoes, and add solar support by placing foam padding to the underside of the hoof. You can also ice the feet by placing rectal sleeves filled with ice around the feet, use 5 liter fluid bags and fill them with ice and tape them around the feet, and there are commercially made "suspender" type boots called "Jack's ice boots".

ISSUES / COMPLICATIONS DURING TREATMENT

Some issues / complications that can occur during treatment of colitis include laminitis, dehydration, jugular vein thrombophlebitis, endotoxemia, and anorexia just to name a few. Severe endotoxic colitis cases can develop disseminated intravascular coagulation (DIC) which is often a fatal complication.

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VETERINARY TECHNICIAN

THE BROAD REALM OF CLOSTRIDIUM

Jamie DeFazio, CVT

Nursing Supervior, New Bolton Center University of Pennsylvania, School of Veterinary Medicine Kennett Square, PA

INTRODUCTION

Clostridial diseases are widely seen in large animal patients. Clostridium is a large anaerobic spore-forming gram positive rod bacterium that lives in the soil, and the intestinal tract of animals. While all of the diseases are of the same bacteria, the clinical disease can be vastly different. Throughout this talk we will discuss the background, clinical signs, treatment and prevention of the more common clostridial diseases that affect the equine and bovine patient. Focus will be on C. botulinum, C. tetani, clostridial enterocolitis in the equine patient (due to C. difficile and C. perfringes), as well as clostridial myositis. At the end of the presentation, I will present a very interesting case regarding clostridial toxins, and that sometimes "straightforward" cases aren't always as they seem. In the case, we will look at a mare that presented for colic, and then, within 24 hours of hospitalization started showing signs of profound botulism, and then developed a clostridial myositis.

DISCUSSION OF DISEASES

C. botulinum Botulism is caused by C. botulinum, of which there are 7 types (A, B, C, D, E, F, and G). Most commonly, types B, C and D affect horses, whereas type D affects cattle. Botulism is an intoxication, and should not be referred to as an infection. There are two routes of intoxication; ingestion of spoiled feedstuffs or infected carcasses, and also the toxicoinfectious type in which the toxin infiltrates necrotic tissue. Intoxication due to ingestion most likely comes from silage, large hay bales, or other contaminated feedstuff. The most likely route of spoilage is through the feed somehow getting processed with tissue from an infected carcass. The toxicoinfectious route usually occurs through a necrotic wound, or other necrotic tissue (GI ulcer, infected umbilicus...). The toxicoinfectious form is usually what causes "shaker foal syndrome" in foals of 2-8 weeks. No matter what the cause of the intoxication, the clinical signs are all the same, and a gradual flaccid motor paresis occurs, starting with involuntary muscles. The signs can start off as a mild weakness or ataxic gate, along with muscle trembling and excessive lying down. The animal may appear to be showing signs of colic due to the lying down and possible associated decrease in manure and borborygmi. Other signs include a dull facial expression, excessive salivation, mydriasis, inability to swallow food, inability to retract tongue, decrease in tail, anal and eyelid tone, inability to urinate, and eventually recumbency. Once recumbent, the animal can rapidly deteriorate and die, even with aggressive treatment. Usually as the paresis moves to the involuntary muscle groups like the muscles of the diaphragm and the heart, death occurs. Diagnosis of botulism is predominantly based on clinical signs and by eliminating other neuromuscular or gastrointestinal differentials from the list. Geographic location is important, as well as the patient's botulism vaccine status. Serum, fecal and tissue samples may be submitted, but are not always diagnostic, and they take days to process in which treatment would have already needed to be initiated. If the patient dies, then samples would be taken during the post mortem exam. Treatment all starts with not stressing the patient. These animals should be kept quiet and be allowed minimal movement. The animal should also be treated with the botulism antiserum as soon as the disease is suspected. The antiserum does not "cure" the disease, but in turn binds with the toxin before it attaches to the motor endplates and inhibits the release of acetylcholine. When these endplates are blocked, they prevent the impulse from the nerve to the endplate. The clinical signs may progress for up to 24 hours even after antiserum administration, depending on the severity of the intoxication. Botulism antiserum for types B, C, and D is available from Dr. Robert Whitlock at the University of Pennsylvania, New Bolton

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Center (610-444-5800), and comes in dosages for foals (250 ml) and adult horses (500 ml). The antiserum is expensive, and holds no guarantees. Besides the antiserum, the next major treatment is supportive therapy and care. Parenteral nutrition either intravenously or via nasogastric tube is recommended, since these animals are most likely not able to swallow food and are at a higher chance of developing aspiration pneumonia. Nasogastric feedings are only recommended if the patient can be maintained at least in sternal recumbency. The animal may need to have manure manually evacuated if rectal tone is still affected, and the bladder may need to be catheterized numerous times daily. If there is a wound involved, it must be cleaned, debrided and infiltrated with penicillin. If the animal is recumbent, turning every 4-6 hours is recommended to prevent decubital lesions from occurring. It is important to keep a mattress or padding under the animal if feasible, and keeping a pad under their head to lessen the chance of corneal ulceration. If you are dealing with a foal and there is already respiratory compensation, ventilator support may be necessary. Many of these animals are treated with broad spectrum antibiotics (potassium penicillin) to cover for any secondary complications like pneumonia. A gastrointestinal protectant like sucralfate may also be used to prevent ulceration. As the patient recovers, a sling may be used to stand the animal and support them as they gain their strength back (An example of a sling is the Anderson® sling).

Foal with botulism

Decreased tongue tone as seen with botulism

Prognosis is dependent on the severity of the disease and progression. On average prognosis is guarded, with younger animals having a better success rate. Animals with botulism may take weeks to months to fully recover, but when recovered should have no on-going issues related to the clostridial intoxication. There is a highly effective vaccine available for type B. The botulism vaccine is not a core vaccine, but is highly recommended in endemic areas. C. tetani Tetanus is caused by C. tetani, and causes a toxemia in necrotic tissue. The main route of infiltration of C. tetani is through wounds in soft tissue or the foot, especially deep punctures. Since the organism thrives in an anaerobic environment it infiltrates deep into the tissue and will reproduce rapidly in necrotic tissue and eventually invading the bloodstream and CNS. The incubation time can vary from 1-3 weeks. Wounds should be addressed immediately and all necrotic tissue should be debrided. The area should also be lavaged and infiltrated with penicillin. Tetanus is more widely seen in warmer environments. Clinical signs of tetanus include a rigid and spastic motor paresis in contrast to the flaccid paresis caused by botulism. Usually localized stiffness is noticed first, many times in the masseter muscles. When the masseter muscles become compromised, it becomes more difficult for the animals to prehend food. This compromise of the masseter is also how the term "lockjaw" came about. Usually about a day after initial signs are present, hyperesthesia and spastic behavior is noted.

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In horses, their ears are erect, their tail stands erect, and in both horses and cattle, they will prolapse their third eyelid and take on a "sawhorse" like stance. It is very important to limit stimulus and stress with these patients. Many of the animals will become unsure of themselves and exacerbate the signs due to their flight instinct. In many situations these animals are moved to a padded, well bedded stall where they can be contained. Placing cotton in the ears to limit auditory stimulation is also ideal. It is also recommended that these animals are kept NPO to avoid aspiration. If the animal's spasms are uncontrollable, sedatives like acepromazine may be used, or anticonvulsant medications like phenobarbital. In some cases, the animal may become so spastic that fractures become common complications. Diagnosis is based on clinical signs and history (i.e.-recent wound). An anaerobic culture may be performed if the wound is still present, but is not always a supportive diagnostic. Treatment of tetanus should start with neutralizing unbound toxin by administration of antitoxin. The doses of antitoxin vary, with many administrating a higher dose that probably necessary. Most antitoxin is administered IV or IM, but it can also be given intrathecally, which may improve the survival rate. Once the antitoxin is given, it must be followed by the toxoid to induce a protective immunity that does not occur from the disease process. Other treatment besides the antitoxin include: supportive therapy, and nursing care. Since these animals may not be eating, parenteral nutrition may be necessary. It is also important to have continued limitations to stress and noise, as these patients continue to be hyperesthetic. Broad spectrum antibiotics may be warranted, especially if secondary complications like pneumonia occur. Support with a sling (like the Anderson sling®) is recommended if the patient will tolerate it. The recovery period may take months depending on the severity of the disease. The average prognosis is fair to guarded if caught early on and poor to grave if the animal progresses rapidly to recumbency. There is a highly effective vaccine on the market, which is a core vaccine. Animals should receive a booster vaccine yearly, as well as if they sustain a wound or puncture within 6 months of being vaccinated. Clostridial Enterocolitis There are two main forms of clostridium that are known to cause enterocolitis in the equine patient, and they are C. difficile and C. perfringens. Both of these organisms can induce similar clinical signs, but may have slightly different etiology. The Sources of clostridial organisms are intestinal mucosa, feces, soil, and water. Animals that are predisposed could have intestinal mucosal damage, could be young, be geriatric, be immunosuppressant, have had a change in diet, or are on antimicrobials. Clinical signs of animals presenting with a clostridial enterocolitis can be very similar to salmonellosis, Potomac horse fever, and also monocytic erhliciosis, so it is important to obtain a fecal or tissue sample for anaerobic culture to confirm diagnosis of clostridium. Clinical signs include abdominal pain, diarrhea (may or may not be bloody), anorexia, dull mentation, dehydration, toxemia, and shock. C. difficile is not as commonly found as C. perfringens, and has two types, A and B. Type A is an enterotoxin that causes hypersecretion of fluid into the intestinal lumen and causes tissue damage. Type B is a strong cytotoxin that induces inflammation and necrosis. Commonly C. difficile is seen in animals that have recently been treated with antibiotics. Erythromycin and Trimetoprim Sulfonamide are two common causative antibiotics. There is also a correlation that mares are more susceptible to developing an enterocolitis caused by C. difficile if their foals are being treated with Erythromycin. A sign more commonly associated with this form is also abdominal distention, which is found less often with C. perfringens. A good preventative measure for C. difficile is to choose antibiotic therapy carefully and use antibiotics like metronidazole and chlorophenicol in high-risk animals. C. perfringens has five types; A, B, C, D, E, and a new type 2. C. perfringens is commonly found in small amounts in all gastrointestinal tracts, but becomes a problem when there is a stress to the animals system. Whereas all of these types cause the same clinical signs, they are all different and carry a separate harm. Type C for instance is usually responsible for a fatal enterocolitis in foals, whereas type A is responsible for enterotoxin release. There is also a new (necrotizing) toxin, 2, which is strongly associated with colitis in horses. C. perfringens is also the main cause of necrotizing enterocolitis is neonatal foals, commonly causing a bloody diarrhea. Necrotizing lesions are seen either during an exploratory celiotomy or during necropsy.

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Treatment of clostridial enterocolitis is very supportive and intensive. Medical treatments include intravenous fluids, nonsteroidal anti-inflammatory medications (low-dose of Flunixin Meglumine), broad spectrum antibiotics if the animal is septic or leucopenic, a gastrointestinal protectant to protect against ulceration (sucralfate, ranitidine, omeprazole), and metronidazole. If the patient is colicy and cannot tolerate oral nutrition, parenteral supplementation as in TPN may be necessary. There is an antitoxin for types C and D, but it is not approved for use in horses. Saccharomyces boulardii (yeast) is also sometimes used, but many believe that it has no effect. It is thought that the yeast adheres to the toxin binding sites in the intestine. In foals, there are some preventative measures taken, including vaccinating mares in high risk areas twice with the C and D toxoid (not a core or recommended equine vaccine). In some endemic areas, foals may be started soon after birth on a probiotic, as well as the antitoxin and metronidazole. C. perfringens can also cause a profound enterotoxemia. C. perfringens type A is commonly found as part of the normal intestinal tract, but can produce a lethal and necrotizing toxin that has been incriminated in colitis in horses. Clinical signs of enterotoxemia include; diarrhea (with or without blood, dysentery, abdominal pain, convulsions, ulceration, and opisthotonos (when the back arches and the head bends backwards over the back). Types B, C, and D will also cause enterotoxemia, in which D is more common in lambs. Control of enterotoxemia includes vaccinating the dam, administering hyperimmunized plasma, and starting antibiotics. Clostridial Myositis (Myonecrosis) Clostridial myositis can occur in one of two ways, either through wound infiltration, or at the site of a non-antibiotic IM injection site. The most common route is through the IM injection site, with Flunixin Meglumine being the usual drug, as it is the most commonly given IM injection that is not an antibiotic. Clostridia infiltrate through the site and invade muscle tissue, causing a rapid and life threatening necrosis. The most common types are C. perfringens, C. septicum, and C. chauvoei. These are also the causative organisms along with C. novyi and C. sordellii that cause malignant edema and blackleg in cattle and sheep. A myositis caused by C. perfringens seems to carry the best survival rate. Clinical signs include an acute and painful swelling, many times at the sight of the recent injection. The swelling is usually warm and soft at first, before becoming cool and firm from the necrosis settling in. The animal will seem stiff, especially in the area of the injection. Animals that received the injection in the neck may have difficulty raising their neck. Crepitus may be felt from gas pockets under the skin, but not always the case. The animals may seem dull or depressed and have an elevated heart rate and respiratory rate due to the pain. Treatment should be imminent, as the disease can progress rapidly. Surgical incision (Fasciotomies) should be performed sooner than later, and an anaerobic culture can be taken (not always diagnostic). The sample should be evaluated after gram stain to look for gram positive rods indicative of clostridia.

Fasciotomy site

Fasciotomies infiltrated with hydrogen peroxide

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The area should be open to the air to kill the anaerobic organism. In many cases, oxygen is inserted into the deeper tissues with a cannula to get into areas that are less likely to be exposed to air. Also, lavaging the area with hydrogen peroxide has been shown to be effective. Animals should be treated with penicillin, and an oral anti-inflammatory. Hydrotherapy has also shown added benefits along with physical therapy to encourage movement of the affected area. In many of these cases, the animal should be maintained on intravenous fluids, and may need parenteral nutrition. It may take several weeks for a full recovery.

CASE STUDY

A case will be presented based on a patient that was admitted for colic and thought to have had a displacement. Approximately 24 hours after presenting for colic she developed clinical signs of botulism and 12 hours after that had a clostridial myositis develop on her caudal neck.

REFERENCES

Manual of Equine Emergencies - Treatment and Procedures. Orsini, James A. and Divers, Thomas J. Saunders 2003 Manual of Equine Medicine and Surgery. Colahan, Mayhew, Merritt, and Moore. Mosby 1999 The Merck Veterinary Manual, 9th edition. Kahn, Cynthia M. (editor). Merck 2005

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VETERINARY TECHNICIAN

EQUINE INFECTIOUS RESPIRATORY DISEASES: CONTAINMENT, CLEANING, AND CONTROL

Barbara Dugan, CVT

Veterinary Technician, New Bolton Center University of Pennsylvania, School of Veterinary Medicine Kennett Square, PA

INTRODUCTION

Infectious respiratory diseases are a major concern among horse owners and veterinary professionals. Equine respiratory disease can be divided into several categories: infectious, non-infectious, upper airway and lower airway. Bacterial and viral agents causing respiratory infection are highly contagious and easily transmissible, via aerosolization, direct contact, contaminated equipment, poor ventilation and fomite. Infectious respiratory diseases can devastate herds of horses, be economically challenging for owners and compromise other patients in the clinical setting. Streptococcus equi sub-species equi (Strangles), Equine Herpes Virus (EHV) (Equine Viral Rhinopneumonitis), and Equine Influenza are of major concern. Other problematic infectious respiratory diseases are Rhodococcus equi and Equine Viral Arteritis (EVA). Veterinary professionals have a responsibility to recognize clinical signs of infectious respiratory disease and know the biosecurity protocols necessary to contain them, protecting other equine patients.

INFECTIOUS RESPIRATORY DISEASES

Strangles is the most common infectious upper respiratory disease of the horse. A highly contagious upper respiratory disease, it is caused by the Streptococcus equi bacteria. This bacterium normally infects the submandibular and retropharyngeal lymph nodes. An uncommon, but possible, sequela of strangles is migration of S.equi bacteria to other lymph nodes of the body producing "bastard" or metastatic strangles. The term strangles is used to describe this infection because lymph nodes can become so enlarged that they actually cut off the airway and suffocate the horse, in essence strangling it. S.equi is spread via direct contact with an infected animal or contamination of equipment, pastures and feed tubs. S.equi is inhaled or ingested and infiltrates the mouth or nose, attaching to the cells in the crypt of the lingual and palatine tonsils. S.equi can also permeate the guttural pouches, where it can survive for months to years. Clinical manifestation of strangles begins with an acute onset of fever, followed by nasal discharge. Nasal discharge can initially be clear and quickly progresses to mucopurulent. Severe swelling and subsequent abscessation of lymph nodes then occurs. Lymph node swelling can become so great that it obstructs the upper respiratory tract. Guttural pouches can be affected; coughing with large amounts of pus from mouth or nostrils can indicate guttural pouch empyema. Other clinical signs can include dysphagia, pharyngitis, and upper airway stridor. Clinical signs are age related, with younger horses being more severely affected than older horses. Diagnosing strangles revolves around laboratory testing and clinical signs. WBC (white blood cell) count and fibrinogen will be increased. Nasal swabs and nasopharyngeal washes are highly effective in identifying S. equi bacteria. Pus aspirated from abscesses is also instrumental in diagnosing strangles. PCR (polymerase chain reaction) testing is useful in detecting asymptomatic carriers, establishing infectious status prior to or following transport and determining the success of elimination of S.equi from the guttural pouch. Endoscopic evaluation of guttural pouches should be performed on all horses with a positive PCR because the guttural pouches can harbor S.equi even in asymptomatic horses. SeM-specific ELISA, basically an S.equi antibody titer, can be used to determine recent (not necessarily current) infection and the need for vaccination; it may also support diagnosis of "bastard" strangles. Treatment of horses with strangles depends upon the stage and severity of the disease. Frequently, the only therapy necessary is to allow the disease to run its course by isolating and stall resting infected animals. Antibiotic therapy in most studies seems to be contraindicated, however if antibiotics are used, S. equi is consistently sensitive to penicillin. Antibiotic use in the early acute stage could prevent abscessation; however, this may also inhibit the production of antibodies and reinfection is likely to occur. Lymph node involvement also precludes the use of antibiotics because it only prolongs the inevitable enlargement and rupture of abscesses. Antimicrobials can be used to stop further enlargement of lymph nodes if partial airway obstruction is present and complete airway obstruction is a concern. Topical treatments such as hot packs or

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poultices may facilitate rupture and drainage of the abscess. Open abscesses should be flushed daily with 3-5% providoneiodine until drainage subsides. Administering non-steroidal anti-inflammatories (NSAIDs) is beneficial for reducing fever, pain and swelling of lymph nodes. Complete airway obstruction will require a tracheostomy. Secondary infections or other complications may require more intensive supportive care, such as IV fluid therapy and feeding by nasogastric tube. Complications associated with S.equi infection, although rare, include metastatic/ "bastard" strangles, immune-mediated processes and agalactia. S.equi can infect any anatomic site. Metastatic/ "bastard" strangles commonly infects the lungs, mesentery, liver, spleen, kidneys, brain and other lymph nodes. Pneumonia is a frequent sequela of strangles and frequently results in death. Purpura hemorrhagica an immune-mediated complication is a systemic illness characterized by extensive ecchymosis and hemorrhages from mucous membranes. Myopathies, such as muscle infarction and rhabdomyolysis, are secondary complications of purpura hemorrhagica. Agalactia has been reported in broodmares with strangles. Equine Herpes Viruses are another source of extremely contagious respiratory disease in horses. Equine Viral Rhinopneumonitis (EVR) is predominantly caused by EHV-4. EHV-1, commonly associated with reproductive and neurologic disorder, is also capable of causing EVR. Equine herpes viruses are universal to all ages and sexes of horses and can result in serious clinical disease. EHV-1 and -4 are most commonly found in horses less than 3 years of age. EHV-1 and -4 are transmitted in one of three ways. Direct contact with the nasal secretions of an infected animal is typically how horses become infected. Inhalation of droplets aerosolized by coughing is another route for this contagion. Indirect contact with a contaminated environment is also a significant factor in EHV transmission. Latent carriers can be present or introduced into the herd. Most horses are latent carriers; in latent carriers the disease can lay dormant for months or years, but under stressful conditions can be reactivated, thus infecting other horses. The incubation period for EHV is 2-10 days. The virus causes inflammation of the lungs and upper airways. Clinical signs of EHV include fever, serous nasal discharge, cough, decreased appetite and potentially the enlargement of lymph nodes. Uncomplicated cases usually recover in 2-3 weeks, if the neurologic disease manifests itself, recovery is guarded. Once the animal is infected it is always infected. One complication associated with EHV is secondary bacterial infection. Serious diseases in other organ systems may occur, such as reproductive issues in the mare. EHV-1 and -4 have the potential to cause late term abortion in pregnant mares as well as foal death within 1-2 days of being delivered. Diagnosis cannot be obtained by clinical signs and physical exam alone because EHV cannot be differentiated from other infectious sources of respiratory or neurologic disease. Virus isolation is the only way to determine EHV. Nasopharyngeal swabs are obtained for culture. Blood sampling and PCR (polymerase chain reaction) are also useful tools in diagnosing EHV. There is no specific treatment for EHV. Treatment involves letting the disease run its course in horses not severely affected or displaying symptoms of the neurologic form of EHV. Stall rest and isolation of infective horses may be all that is necessary for a full recovery. Minimal supportive care and treating only as symptoms arise is required for mild cases of EHV- associated rhinopneumonitis. NSAIDs, such as flunixin meglumine, can be used to reduce fevers. Antibiotic therapy is only indicated if there is a secondary bacterial infection. A 30 day quarantine of all horses on the property or hospital is required. The 30 days begin when the last case infected displays no clinical signs of disease. Prevention revolves around reducing stress, good management procedures and disinfection of contaminated equipment and environment to help reduce viral spread. Vaccinations may reduce severity and duration of EHV but do not prevent it. Vaccination recommendation is 2 doses at 2-3 weeks of age followed by boosters every 3 months. Isolate any new horses for at least 14 days. Equine Influenza is a highly contagious, commonly diagnosed virus which spreads rapidly among horses. Horses of all ages are susceptible to equine influenza although it commonly affects horses ages 2-3. It is the single most important respiratory disease in all countries, except Australia, New Zealand and Iceland which are the only countries that are influenza free. This virus has world wide economic impact because of how quickly and easily it can be transmitted among horses. The spread of Equine Influenza occurs mainly by inhalation of infected aerosolized respiratory secretions. The virus infects the upper and lower respiratory tract, causing bronchitis, interstitial pneumonia, edema and neutrophilic inflammation.

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100% of exposed horses become infected. Equine Influenza can be shed for 4-5 days after clinical signs arise, and horses can continue to spread the virus for another 7-10 days post recovery. Clinical signs include fever, deep dry cough, serous to mucopurulent nasal discharge, depression, myalgia, anorexia and enlarged lymph nodes. Colic and edema of the limbs and scrotum have also been observed. Secondary bacterial infection, pleuropneumonia, and myocarditis causing cardiac arrhythmias are additional complications of Equine Influenza. Diagnosis is based on virus isolation from nasopharyngeal swabs, taken at the onset of illness. Using paired serological testing for antibody titer and the Directigen Flu-A test, Equine Influenza can be identified. Radiographs may reveal a mixed bronchoalveolar pattern with an increased interstitial pattern. An endoscopic evaluation of the pharynx, larynx and trachea may show inflammation and is an excellent way to obtain culture for cytology. Equine Influenza requires supportive care and symptomatic treatment. Isolating infected horses, decreasing stress and providing one week of rest for each day of fever are the keys to recovery. Anti-inflammatories are used to reduce fever and relieve muscle pain. Antibiotics are administered only if secondary bacterial infection is present. Prevention is aimed at isolation of all infected patients. Vaccinations, as with EHV, will lessen the severity of disease but not necessarily prevent Equine Influenza. Excellent farm management is needed. Good personal hygiene can help prevent personnel spreading the virus from patient to patient. Disinfection of all contaminated materials is necessary in any area exposed to this virus. Rhodococcus equi is a gram positive bacterial organism which is a normal inhabitant of the soil and causes serious pneumonia in 1-4 month old foals. It is transmitted by inhalation of dust particles or consumption of infected feces. Immunosuppressed adult horses can be susceptible to this bacterium. Rhodococcus infection may also cause diarrhea, joint sepsis, intra-abdominal abscess as well as multifocal abscess. Clinical signs include fever, cough, lethargy, depression, anorexia, diarrhea, joint infection and respiratory distress. Secondary bacterial infection, drug-induced diarrhea and extra-pulmonary symptoms are common complications of R.equi. Physical exam and clinical signs are the first indicators of R.equi infection. Blood samples may reveal an increased white blood cell count and hyperfibrinogenemia. Definitive diagnosis is based on nasal swab culture results. Ultrasound will show an interstitial pattern within the thorax. Radiographs are also useful for diagnosis, interstitial pattern, consolidation and comet tails are typical radiographic findings. Nursing and supportive care of mildly affected foals, along with antibiotic therapy using the combination of erythromycin and rifampin may be all that is required for recovery. Reducing stress and managing the patient in a climate controlled environment are beneficial. Isolation of infected foals should be considered to prevent spreading of disease. Commercially produced R.equi hyperimmune plasma can be administered to increase foal immunity to the bacteria. Foals with respiratory distress will require intranasal oxygen therapy and potentially nebulization with albuterol and ipratropium bromide. A major preventative measure for R.equi is early disease detection. A daily PE along with weekly to monthly white blood cell counts and fibrinogen tests may aid in early detection of R.equi and allow for prompt isolation of foals with abnormal PE or blood values. Management practices are always important. Hyperimmune plasma administration at 1-2 days old may help decrease incidence of disease. Finally, Equine Viral Arteritis (EVA) is an acute contagious viral disease that mainly causes abortion but can produce respiratory disease. Respiratory EVA exhibits the same clinical signs as EHV. EVA is characterized by vasculitis leading to edema, hemorrhage and abortion in pregnant mares. EVA may cause respiratory disease in other adult horses and severe illness to death in neonates. EVA is most commonly transmitted sexually, although aerosolization of respiratory secretions and fomites frequently causes the spread of the virus. EVA replicates in alveolar macrophages then localizes and multiplies in the lymph nodes and is widely dispersed to various tissues and fluids. This viral infection is present in most countries and associated with moving horses or shipping semen. It is concerning that EVA is sub-clinical in most cases and thus difficult to detect early in the disease process. However, if the virus load becomes severe, clinical manifestations include fever, leukopenia, depression, and anorexia and hind limb

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edema, Edema of the prepuce and scrotum may also occur. The virus is most severe in young, old and immunosuppressed horses. Virus isolation and PCR of nasal secretions will aid in identification of EVA. Paired serological tests, conjunctival swabs and virus isolation from semen are all relatively reliable for diagnosis. There is currently no specific treatment protocol for EVA. Supportive care is indicated and isolation of infected horses (especially during an outbreak) will protect other horses. Hydrotherapy my help reduce edema caused by EVA. Antiinflammatory and diuretics will aid with fever and reducing edema. Neonatal patients will require intensive nursing care. Intravenous fluid administration, feeding via indwelling tube, total parenteral nutrition and respiratory management may all be necessary for the survival of an infected foal. Prevention is geared toward client education, good management practices and hygiene. Vaccination, of horses less than six months of age (with the exception of pregnant mares), will minimize the risk of abortion and prevent stallions from becoming long term carriers.

CONTAINMENT, CLEANING, CONTROL

The route of transmission for equine respiratory diseases creates a challenge for containment in the clinical setting. Pathogen carriage by infected animals as well as sub clinical carriers is always present in the hospital. Multiple animals housed relatively closely plus numerous people handling these animals increases the potential for spread of infectious diseases. Preventing an outbreak is essential. Some infectious respiratory diseases have the potential to travel significant distances, which is the case with Equine Influenza. Any horse suspected of having an infectious respiratory disease should be isolated and kept away from the general population of animals in the hospital. In cases where an isolation stall is not available, house an infectious animal at the far end of a barn with at least one buffer stall to protect other patients. Implementation of isolation and biosecurity protocols should be initiated in this situation. A 1% bleach solution, quaternary ammonium and phenols are common disinfectants that will kill most infectious respiratory diseases. Most equine infectious respiratory diseases are susceptible to these products. Meticulous care and attention is required to ensure every possible surface that could be contaminated gets disinfected. A three step cleaning process helps ensure all surfaces are decontaminated and disinfected. The three steps are as follows: scrub with detergent to remove gross debris, coat stall in a disinfectant, rinse and disinfect with some other broad spectrum disinfectant, No infection control program can eliminate disease concerns. Controlling the spread of infectious respiratory disease requires awareness of biosecurity protocols. Barrier precautions, such as wearing gowns, gloves, masks, plastic or rubber shoe covers and changing clothes, as well as excellent personal hygiene will help decrease the spread of disease. Equines are affected by infectious as well as non-infectious respiratory issues that have the potential to be debilitating and sometimes fatal. Equine infectious respiratory disease is a major health and economic concern among the equine communities worldwide. Biosecurity protocols, along with understanding the disease processes and how quickly infectious respiratory diseases can be transmitted, are crucial to protecting the animals and preventing the spread of infectious respiratory diseases.

REFERENCES

Aiello, SE. Merck Veterinary Manual. Equine Herpesvirus Infection 2008 http://www.merckvetmanual.com/mvm/htm/bc/121302.htm> Aiello, SE. Merck Veterinary Manual. Equine Influenza. 2008 <http://www.merckvetmanual.com/mvm/servlet/CVMHighLight?file=htm/bc/121303. htm> Aiello, SE. Merck Veterinary Manual. Rhodococcus equi pneumonia. 2008 <http://merckvetmanual.com/mvm/htm/bc/121307.htm> Aiello, SE, Merck Veterinary Manual. Equine Viral Arteritis: Introduction. 2008 <http://www.merckvetmanual.com/mvm/htm/bc/52900.htm> American Association of Equine Practitioners. Streptococcus equi var. equi, 2006, <http://www.aaep.org/pdfs/control_guidelines/Streptococcus%20equi%20var.pdf> American Association of Equine Practitioners. Rhodococcus Equi in Foals: An Update on Epidemiology, Diagnosis, Treatment and Prevention by R.P Franklin, DVM, Dip.ACVIM, 2008,

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<http://www.aaep.org/health_articles_view.php> American Association of Equine Practitioners. Equine Influenza, 2008, <http://www.aaep.org/page_editor_page_preview.php> American Association of Equine Practitioners. Equine Viral Arteritis, 2008, <http://www.aaep.org/page_editor_page_preview.php American Association of Equine Practitioners. Equine Herpesvirus, 2006, <http://www.aaep.org/pdfs/control_guidelines/Equine%20Herpes%20Virus.pdf> American Veterinary Medical Association. Equine Influenza Backgrounder, 2006, <http://www.avma.org/public_health/influenza/equine_bgnd.asp> Allen, G. P. Respiratory Infections by Equine Herpersvirus Types 1 and 4, 2002, International Veterinary Information Service, <http://www.ivis.org/special_books/Lekeux/allen/IVIS.pdf> Brown, Christopher M, Bertone, Joseph J. The 5-Minute Veterinary Consult: Equine. 3rd edition. Blackwell Publishing; 2005 p. 508-511, 566-569,930-931, 1024-1025, 1124-1125 Dwyer, R.M. Environmental disinfection to control equine infectious diseases. Veterinary Clinics: Equine Practice. 2004. p. 531542 Giguère, S. Rhodococcus equi infections. 2000, International Veterinary Information Services, <http://www.ivis.org/advances/Neonatology_Wilkins/giguere_rhodococcus/IVIS.pdf> Iowa State University, the Center for Food Security and Public Health. Equine Viral Arteritis. 2009 <http://www.cfsph.iastate.edu/Factsheets/pdfs/equine_viral_arteritis.pdf> OIE Terrestrial Manual. Chapter 2.5.9, Equine Rhinopneumonitis. 2008. <http://www.oie.int/eng/normes/mmanual/2008/pdf/2.05.09_EQUINE_RHINO.pdf> Orsini, J.A, Divers, T. J. Equine Emergencies Treatment and Procedures. 3rd edition. Saunders/Elsevier 2008. p. 708-718 Reed, S.M, Toribio, R.E. Equine Herpesvirus 1 and 4, Veterinary Clinics Equine Practice 20. 2004. p. 631-642 Smith, B.P. Large Animal Internal Medicine, 3rd edition. Mosby, Inc. 2002 Sweeney, C.R, Timoney, J.F, Newton, J.R, Hines, M.T. Streptococcus equi Infections in Horses: Guidelines for Treatment, Control, and Prevention of Strangles. ACVIM Consensus Statement. Journal of Veterinary Internal Medicine 2005, p. 123-134 University of Connecticut, Department of Animal Sciences. Fact Sheet. Equine Herpesvirus by Nadeau, Jenifer. <http://www.canr.uconn.edu/ansci/ext/herpesvirus.htm> University of Delaware. Cooperative Extension. Equine Herpesvirus Disease by David Marshall, VMD. 2006 <http://ag.udel.edu/Extension/agnr/pdf/eq-11.pdf> University of Delaware. Cooperative Extension. Equine Influenza by David Marshall, VMD. 2007 <http://ag.udel.edu/Extension/agnr/pdf/eq-12.pdf> University of Georgia, Equine Herpesvirus (EHV-1) and (EHV-4) (Equine Viral Rhinopneumonitis) <http://www.vet.uga.edu/VPP/ivm/ENG/ERD/EHV-4 and 1.html University of Georgia, Equine Viral Arteritis <http://www.vet.uga.edu/VPP/ivm/ENG/ERD/EVA.html Weese, J. S. Barrier precautions, isolation protocols, and personal hygiene in veterinary hospitals. Veterinary Clinics: Equine Practice 20. 2004. p. 543-559 Wilkins, P.A. D.V.M, Lower airway diseases of the adult horse, Veterinary Clinics: Equine Practice 19, 2003 p. 101-121

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VETERINARY TECHNICIAN

COMMON NEUROLOGIC DISEASE OF THE SOUTH AMERICAN CAMELID

Barbara Dugan, CVT

Veterinary Technician, New Bolton Center University of Pennsylvania, School of Veterinary Medicine Kennett Square, PA

INTRODUCTION

The South American camelids are becoming an increasingly common patient in the veterinary clinical setting. Camelids, being prey animals, are less likely to display signs of disease until critically ill. As the popularity of these unique creatures grows, so does the knowledge of veterinary professionals in order to properly and effectively treat them. A frequent reason camelids present to clinics is neurological disease. In the United States, Parelaphostrongylus tenuis and heat stress are typical causes of neurologic disorder in camelids. Veterinary technicians, as part of the veterinary team, need to have a basic knowledge of the disease process and clinical signs of these neurologic diseases. Technicians should also know their role in supportive care for theses patients.

THE MENINGEAL WORM

Parelaphostrongylus tenuis (P. tenuis), the meningeal worm, is a nematode whose definitive host is the white-tail deer. P. tenuis lives in the veins and sinuses of the dura mater of the deer. The deer and parasite coexist, with the deer unaffected by it presence. Camelids are an aberrant host for P. tenuis. In an unnatural host P. tenuis can cause severe neurological damage that can lead to death. The life cycle of P. tenuis begins in the veins and sinuses of the dura mater of the white-tailed deer. Adult female nematodes lay their eggs, which hatch in the lungs. The larvae are then coughed up and swallowed. Larvae are passed in the feces of the deer. Snails and slugs crawl through the feces collecting the larvae. Grazing camelids ingest the snails and slugs. Consumed larvae migrate to the spinal cord, causing damage. Experimental infection of six llamas with P. tenuis caused clinical signs of meningeal worms 45-53 days post inoculation. Clinical signs of P. tenuis can range from lameness; to paralysis; to death. A common presentation for camelids, affected by P. tenuis, is a wide hind end stance and hind end ataxia progressing to recumbency. Front limbs are rarely affected until recumbency becomes prolonged. Camelids with P. tenuis tend to be bright and alert with good appetites. Acute onset of clinical signs is rare, unless larval migration to the brain occurs. Normally there is a gradual progression of neurologic signs. Clinical signs associated with the atypical version of P. tenuis include all of the aforementioned clinical signs as well as depression, seizure, coma and pupillary light reflex. Diagnostic procedures though not definitive can help narrow down the reason for neurologic disease. Blood sampling should be done to rule out other potential causes of camelids presenting neurologic. A cerebral-spinal tap will likely be performed. A CSF tap could reveal an eosinophilia which is a common yet inconsistent finding in cases of P. tenuis. A tentative diagnosis can be based on clinical signs, history of exposure to white-tailed deer and response to treatment. Definitive diagnosis is only gained at necropsy. Treatment for P. tenuis revolves around drug therapy, supportive care and physical therapy. The treatment regiment could include one or all of the following medication: fenbendazole, an anthelmintic is used to deworm the patient, it should be administered once a day for five days; flunixin meglumine, an anti inflammatory, reduces swelling of the spinal cord, can be administered twice a day for five days; and/or dexamethasome, an anti inflammatory, administered once a day for 3 days. This protocol has been used successfully at Ohio State University. Vitamin therapy may aid in healing of neural tissues. Supportive care is also crucial to the recovery of the camelid. Intravenous fluid therapy can be beneficial especially if inappetence or anorexia is an issue. Physical therapy may include passive range of motion, sling therapy or aqua therapy. Physical therapy is important to prevent additional muscle wasting due to prolonged recumbency. Recovery of affected camelids can take anywhere from weeks to years.

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Prognosis of camelids with P. tenuis is guarded. Camelids that are not recumbent usually recover. Any animal that is recumbent for an extended period of time has a poor prognosis. Any neurologic deficits remaining six months post treatment are likely to be permanent. Client education is an important first step to prevent this parasite and protect their herds. A management procedure, such as deer-proof fencing, to limit deer access into pastures is important. Molluscicides can be used to decrease the number of snails and slugs in the pasture. A strict deworming protocol should also be used to decrease incidence of P. tenuis infection. Ivermectin is the dewormer of choice but most effective when administered in the early stages of infestation. Prevention of P. tenuis, though difficult, can be achieved.

HEAT STRESS

Camelids, native to the cooler temperatures of the Andes Mountains, are less adaptable to the hot and humid weather in the United States. Heat stress is a common problem for camelids in our region. The normal core body temperature for the adult camelid is 99.5-101.5, but during a hot summer day a temperature of 104 would not be unusual. Neonatal camelids temperatures will be a degree warmer than an adult. Heat stress has profound effect on the central nervous system causing neurologic disorder. Hyperthermia can be caused by high environmental temperatures, humidity, activities that cause stress, such as packing or racing, as well as by fevers and disease. Clinical signs of hyperthermia or heat stress are a core temperature in excess of 104. Respiratory signs include, open mouth breathing and tachypnea. The cardiovascular system is also affected with camelids being tachycardic with decreased perfusion. CNS signs displayed are depression, inability to stand, front limb weakness, inappetence and ataxia. Other organ systems can also be affected, such as the intact male camelids scrotum which gets "saggy", pendulous or edematous. Diagnosis revolves around ruling out other causes for neurologic disease. Tentative diagnosis can be made with significant increases in the base-line TPR, redness of skin, sweating and dehydration. Blood work may reveal marked elevations in the muscle enzymes CK (creatinine kinase) and AST (aspartate aminotransferase) as well as a low total protein due to cell damage. Treatment is aimed at first and foremost cooling the animal. This can be accomplished by using ice packs in the inguinal and axillary regions of the camelid. Cold hosing can also be used to reduce the core temperature. Administration of intravenous fluids at maintenance rate (30-40ml/kg/day) can help rehydrate and rebalance electrolytes; however caution should be used in patients with hypoalbuminemia because pulmonary edema can occur quickly due to cellular damage. Anti inflammatories may be beneficial to relieve any pain or soreness, as well as vitamin therapy for its antioxidant properties. Supportive care could include sling or aqua therapy for recumbent camelids. Monitor temperature closely because camelids have a difficult time thermoregulating after an incidence of heat stress. Prognosis for camelids affected by heat stress is good if clinical signs are seen and treated quickly. Severe respiratory distress can cause pulmonary edema and ultimately death. Prevention should be geared toward farm management. Camelids should be sheared prior to summer. They should have plenty of shade and cool water available. . Having a pond or wading pools available so camelids can cool themselves is also recommended. Teaching owners about clinical signs and monitoring temperatures in warm water can help with early detection and prompt cooling.

UNCOMMON NEUROLOGIC DISEASE

Neurologic diseases more commonly associated with ruminant and the equine populations have been reported to infect camelids. Uncommon causes of neurologic disease include rabies, listeriosis, polioencephalomalacia and viral encephalitis; as well as equine herpes virus-1, West Nile virus and Eastern equine encephalitis; which are more commonly thought of as equine neurologic diseases. Clinical signs associated with uncommon causes range from acute onset blindness, depression, ataxia, hyperesthesia, aggression and seizures leading to death. Diagnostics should include CBC and chemistry as well as a CSF tap. Generally, this is only a tentative diagnosis; definitive diagnosis can only be made on necropsy. Treatment revolves around aggressive drug therapy, supportive care and monitoring. Prognosis for camelids is guarded to poor even with the

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most aggressive supportive care. Prevention involves client education, herd management, routine vaccination protocols and limiting camelid access to causative agents, for example not housing camelids and horses together.

CAMELID HANDLING

Camelid handling is a unique challenge. These patients feel most secure within the herd. Removing them from the safety of their natural environment can cause stress. Stressful situations in turn can trigger their defense mechanisms. Spitting, pulling hair, biting and kicking are common defensive behaviors. When attempting to restrain these patients; calm, quiet and fluid approach helps reduce the camelids anxiety. Gently placing an arm around their neck will usually allow you to catch and restrain them.

THE RECUMBENT CAMELID

Recumbent animals present a different challenge. A "down" camelid requires aggressive supportive care. Recumbent animals should be turned every 2-4hours to help reduce pressure sores and prevent pneumonia. They should be moved to dry area of the stall so any wet bedding or feces can be removed to reduce urine scalding and feces matting in their fiber. A frequent concern with recumbent camelids is a secondary medical issue. Commonly gastrointestinal issues arise in these animals when stressed. Clinical signs of GI distress include anorexia, grinding teeth, dysphagia, abdominal distention and colic. Treatment includes drug therapy with GI protectants and transfunation. This treatment protocol is used to help stimulate the GI motility, coat and soothe the stomach, stimulate appetite and return much needed microorganisms to the rumen. Camelids can also develop hepatic lipadosis. Clinical signs include anorexia and weight loss as well as insulin resistance and hypoproteinemia. Treatment includes administration of insulin and/or heparin, IV fluid therapy, nutritional support. Monitoring of blood glucose, urine output, and renal function, as well as, serum electrolytes is important.

THE VETERINARY TECHNICIANS' ROLE

The veterinary technicians' role can vary. Often technicians are needed for supportive care and monitoring. Critical thinking and assessment skills are needed to closely monitor the camelid for subtle changes in behavior, attitude, appetite and overall status. Understanding the clinical signs and disease process is crucial to provide the best patient care possible.

CONCLUSION

Camelids are affected by numerous neurologic diseases; some until recently only thought to affect other species. Comprehension of the disease process and clinical signs is necessary for prompt, proper and effective treatment of these patients. Secondary problems, due to the effect of primary disease can occur. Close observation of neurologic camelids is vital, even subtle changes in attitude, appetite and behavior can be significant. Although prognosis for neurologic camelids is guarded at best, the earlier clinical signs are detected the better chance there is for a positive outcome.

REFERENCES

Aiello, SE. Merck Veterinary Manual. Hyperlipemia and Hepatic Lipidosis in Horses, Donkeys and Camelids. (2008) < http://www.merckvetmanual.com/mvm/htm/bc/22818.htm Anderson, DE. Parelaphostrongylus Tenuis (Meningeal Worm) Infection in Llamas and Alpacas. The College of Veterinary Medicine at the Ohio State University 2009. July 17, 2009 <http://www.vet.ohio-state.edu/378.htm Anderson, DE. Heat Stress in Llamas and Alpacas (2003): Are You Ready for Summer? (2004). The Rocky Mountain Llama and Alpaca Association. September 26, 2009. <http://www.rmla.com/heat_stress.htm Fowler, ME. Parasites. In: Fowler, ME, editor. Medicine and Surgery of South American Camelids. 2nd edition. Ames (IA): Blackwell Publishing; 1998. p. 224-225 Fowler, ME. Multisystem Disorders. In: Fowler, ME, editor. Medicine and Surgery of South American Camelids. 2nd edition. Ames (IA): Blackwell Publishing; 1998. p. 235-240 Dunkel, B, Del Piero, F. Wotman, KL, Johns, IC, Beech, J, Wilkins, PA. Encephalomyelitis from West Nile Flavivirus in 3 Alpacas. Journal of Veterinary Internal Medicine (2004). p.265-267

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Durkes, A. Parelaphostrongylus tenuis infection in Llamas. Winter news letter 2008, Perdue University. July 17, 2009 <http://www.addl.perdue.edu/newsletter/2008/lama.htm Nolan-Walston, R, Bedenice, D, Rodriquez, C, Rushton, S, Bright, A, Fecteau, M, Short, D, Majdalany, R, Tewari, D, Pedersen, D, Kiupel, M, Maes, R, Del Piero, F. Eastern Equine Encephalitis in 9 South American Camelids. Journal of Veterinary Internal Medicine (2007) p. 846-852 Whitehead, CE, Bedenice, D. Neurologic Diseases in Llamas and Alpacas. Vet Clin Food Animal 25 (2009) p. 385-405

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VETERINARY TECHNICIAN

STOP THE SPREAD: BIOSECURITY IN LABORATORY ANIMAL SCIENCE

Mary Kate Goldy, BA, MLAS ­Anesthesia Veterinary Technician Specialist Jennifer Kirsch, BA, RLATG ­ Senior Anesthesia Veterinary Technician Specialist

University of Pennsylvania, School of Veterinary Medicine Philadelphia, PA

Biosecurity in laboratory animal science revolves around a well-managed and strictly enforced health surveillance program. Upholding the steps to the crucial process of biosecruity helps maintain healthy colonies, accurate research data, and ultimately protects members of the research community. When the system breaks down, pathogens have a greater opportunity to attack the core of the research institution, the animals. Different species of study animals have different common pathogens, and therefore biosecurity programs depend on the species and pathogens that are most likely to present themselves. The keys to success of the program involve eight crucial steps. Step one is having a proper vendor source; the vendor could be a Class-A barrier-type facility with health surveillance programs who can guarantee SPF animals. These facilities typically breed animals specific for research use. Class-B vendors are typically universities, non-commercial institutions, and small biotechnology companies who also supply animals to the research community. Class-C vendors are not used commonly in research; these are pet stores or personal breeders. Step two is strict enforcement of quarantine procedures. For example, withholding animals from investigative use until cleared through quarantine, despite length of time necessary to accomplish this. Step three consists of well-managed, consistent and exceptional levels of animal husbandry practices. Step four is prompt and complete clinical disease investigation, for example, the testing of animals at the vendor and again at arrival in the new facility. Steps five is the use of a sentinel program to assess and monitor the status of existing rodent colonies. Sentinel programs are independent of research and are utilized to ascertain the presence or absence of pathogens or parasites. Step six involves environmental contamination control and containment. Food should be high quality, certified, autoclavable feed which provides the maximum levels of nutrients. Water quality should be maintained and chlorinated; it should be monitored for contamination such as bacterial, chemical, or metal components. Bedding quality is also a function, and should be autoclavable and provide pest resistance. Step seven details microbial and barrier monitoring. The levels of cleanliness are often determined by RODAC testing, autoclave testing, and environmental monitoring. Finally, the biosecurity, if formally documented by organized record keeping, details the previous procedures which have been in use to assure disease free levels. This documentation is mandatory to achieve accreditations to organizations such as AAALAC, Intl. Contrary to popular belief, mice and rats are the most commonly used animal in biomedical research, and generally account 1 for greater than 80% of the animals undergoing research testing and procedures . Both of these widely used species have the potential to develop infectious diseases which could impact research results. As mentioned previously, animal husbandry practices, standard operating procedures, and a well orchestrated health surveillance program will keep diseases out and facilitate consistent research models. Facilities should have established Standard Operating Procedures (SOP's) and quarantine procedures. The immediate placement of animals into the regular colony is dependent of where the animal was procured from. For example, if received from a vendor with an approved standard of testing and quarantine, typically Class-A vendors, the animal may be received into a facility directly, but placed into isolation rooms until their health status can be confirmed. Facilities that achieve a higher level of biosecurity typically monitor their animals using serology to test for the presence of viral antibodies, pinworm tape tests, and more recently polymerase chain reaction (PCR) testing, which tests for DNA of 2 pathogens . However, if animals are received from other institutions, specifically non-commercial sources which do not assure a level of disease free status, they should be placed into a quarantine facility or room. Until the health status of these animals can be confirmed as satisfactory, they will remain in quarantine and not be available for research use. If the rodents' health cannot be confirmed satisfactory, the colony should be embryo rederived. Embryo rederivation is used most commonly with rodents when a disease cannot be successfully eradicated from the animal or colony. When a specific strain is important to the research, rederivation is crucial. In embryo rederivation, the rodents presenting with, or suspected of disease have their embryos harvested and transplanted into a disease-free pseudo-pregnant recipient rodent.3

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To maintain a continued level of biosecruity in a facility there should also be routine microbial monitoring. Depending on the SOP's for a facility, monthly or quarterly testing should be performed. Microbial monitoring, while not only important for accreditations, is necessary for both animal and human safety. Monitoring can generate data to develop guidelines to continue an established level of acceptable sanitation. Generally, the monitoring involves the use of agar plates, exposing them to various locations throughout a facility. The plates are exposed to specific surfaces then incubated, and the results are used to determine if levels of sanitation are acceptable or need improvement. Environmental monitoring is also suggested in "The Guide for the Care and Use of Laboratory Animals".4 Ventilation, noise, and illumination are three of the environmental values which should be monitored on a regular basis. Ventilation is important to biosecurity due to the fact that an increase in temperature or humidity can decrease the resistance of an animal's immune system by introducing environmental stressors to the animal. Sentinel animals are used most commonly with rats and mice and are a critical part in biosecurity of a facility. They provide a method of testing for specific pathogens to assess the health of a colony. Sentinel animals should be immunocompetent, 5 greater then 8-12 weeks old, and initially free of pathogens as documented by serology. They are ideally from the same source as study animals, and species, strain, age, and gender, match the colony in the room. They should be housed similar to the study animals or in open top cages depending on the facilities SOP. However, sentinels are purposely exposed to any potential pathogens and have different husbandry procedures. Their bedding and water consists of a proportional mix of dirty bedding and water from other cages throughout the room, thereby providing indirect exposure of any pathogens that may be present on the research subjects within the room. Sentinel animals are normally tested quarterly or semi-annually. Animals are either euthanized and tissues and blood are collected for analysis of pathogen, or they are used for long term monitoring of the colony and serologic blood testing is performed at regular intervals. Finally, a large part of biosecurity that all members of the laboratory animal community have a role in is the wearing of personal protective equipment, or PPE. While the task is simple to appropriately wear and remove PPE, it is an important 4 barrier to inhibit the transfer of pathogens between humans and animals, and animals to other animals. PPE prevents the entrance of contaminants into a facility by providing a barrier between the outside environment and the animal colony. Conversely, PPE protects against pathogens traveling from exposed animals to humans. Most importantly, PPE prevents cross contamination and minimizes outbreaks and the spreading of disease within the colony. If SOP's are followed and PPE is changed between species, rooms, and animals, it can be considered the most efficient way to control disease. Researchers, animal care technicians, and clinical care staff members have an easy, yet important task in ensuring their part in biosecruity. The following is a generalized list of some of the diseases which are common in laboratory animals, and we will begin by comparing and analyzing these to prove the necessity for the procedures listed above.

MHV, or mouse hepatitis virus, is a corona virus that affects digestive tract and immune systems of mice.7 Often, the mice remain asymptomatic, but the disease can have very harsh affects on the immune system; it weakens the overall immune response, decreases lymph production and decreases the phagocytic activity of the immune cells. Severe diarrhea, dehydration, inappetance and even death are clinical signs of MHV. MHV is routinely diagnosed by serological testing, which is the most reliable method of detection. Embryo or cesarean derivations are the most acceptable methods used to rid a colony of MHV. However, a facility can use the "burnout" technique to rid this disease in immunocompetent mice colonies only. This technique involves complete cessation of introduction of new animals to the affected area; this includes no new animal deliveries, no new sentinel placement and stoppage of breeding practices for at least 6-8 weeks. MPV, or mouse parvovirus, is another type of virus found in mice. MPV is always subclinical and can remain latent for long 5 periods of time, but causes alteration in normal immune system function. Unfortunately, MPV is highly contagious and resistant to chemical disinfection. Similar to MHV, MPV is detected via serology testing. Embryo derivation is used to rid colonies affected by this disease; the burnout technique is not viable for eliminating MPV. MVM, or minute virus of mice, is similar to MPV in many ways. MVM is highly contagious, affects the immune and gastrointestinal systems of mice, and can be eradicated using the embryo derivation technique.6

RODENTS

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EDIM, or epizootic diarrhea of infant mice, is a rotavirus that affects the gastrointestinal tract of young mice.6 Usually, mice 2 weeks old and younger are the most affected; adults can carry the virus, but are usually not affected and show no clinical signs. EDIM causes severe, watery, yellow-colored diarrhea, perineal staining, and gradual weight loss. EDIM is very contagious and has high mortality rates in young mice. Embryo derivation and burnout techniques are common for elimination. MNV, or mouse norovirus is said to be the most wide spread disease in the US and Canadian biomedical research colonies, typically affecting immunodeficient mice.5 Transmission is generally via the fecal-oral route. MNV can easily be detected through the sentinel testing program because it can also be transmitted through direct contact with dirty bedding. Again, embryo derivation is an acceptable method to eliminate this common occurrence. Sendai virus is paramyxovirus found in rats and is an acute respiratory disease.7 Mice can also carry Sendai virus, and the clinical signs are often much more severe. Generally, very young and old rats and mice are the most affected; young adults are usually subclinical. Sendai virus is highly contagious and infectious, and can carry a 100% mortality rate. Clinical signs include rapid weight loss, rough hair coat, and scruffy appearance with decreased litter sizes. Embryo derivation and cessation of breeding are the techniques used to rid a colony affected with Sendai virus. SDAV, or sialodacryoadenitis virus is a highly contagious corona virus found in rats, and is closely related MHV in mice.5 SDAV can cause swelling of the neck with salivary gland involvement, decreased feed intake, changes in Harderian gland secretions, ophthalmic lesions (including KCS, or keratoconjunctivitis, commonly known as dry eye). A cessation in breeding for at least 60 days is indicated to rid a colony of this disease and is proven to be effective for elimination of this type of infection. Helicobacter affects both mice and rats and causes gastrointestinal inflammation, which can sometimes lead to hepatic 5 neoplasm. Helicobacter is often the cause of rectal prolapse, a common problem seen in the research community. Also, helicobacter can cause irritable bowel syndrome in SCID (severe combined immunodeficiency) mice. Transmission is via the fecal-oral route, and can be detected via sentinel testing and diagnosed by PCR. Again, as with most of these severe diseases, embryo derivation is the acceptable method for elimination. RRV, or rat respiratory virus, is a relatively newly discovered disease and the agent of infection is currently unknown but thought to be some type of virus.5 It seems as though the 8-12 week old rat is the most affected by lung inflammation. Older rats mostly show no clinical signs, with the exception of increased mortality rates during anesthesia. Detection is limited to histopathology via necropsy. Pinworms are the most pathogenic and most common problem in a research setting.5 Clinical signs can vary and include lethargy, rough coat, dehydration, and general unthriftiness. There are 2 common types of pinworms seen in the research environment, syphacia obvelata and aspicularis tetraptera. Pinworms are easily transmitted on clothing and contact surfaces, and can even be aerosolized. They often remain stable in the environment and are resistant to chemical destruction, making eradication difficult. Treatment consists of antihelminthic drugs, and there is commercial feed available with a common antihelminth, fenbendazole. Rederivation of the colony can be indicated when treatment has failed, and this can be accomplished via c-section or embryo derivation. The use of proper PPE and strict husbandry practices are vital to pinworm containment, eradication and prevention. IUD, or idiopathic dermatitis, is another very common occurrence in a research setting, typically affecting the B57/Bl6 and B57/Bl10 mice. The cause of this disease in unknown, but research has shown that IUD can be both genetic, and have 5 environmental influences. There is no universal treatment for IUD and it can be a very frustrating disease to eradicate. Unfortunately, the common rederivation techniques have not been proven to work to rid a colony of IUD. IUD can have profound effects on research data, and can cause systemic alterations, including splenomegaly and lymphadenopathy.8

LCMV, or lymphocytic choriomeningitis is an RNA arenavirus found in hamsters that often exhibit no clinical signs.7 Mice are also affected by LCMV, and guinea pigs carry this disease and become infected, but do not transmit it. Animals affected by LCMV can develop severe kidney disease and even fatal liver necrosis. This disease is zoonotic and can be transmitted to humans via the saliva, urine, feces and nasal secretions of the affected animal, and can cause flu-like symptoms. The key to containment and eradication of this disease is strict husbandry practices.

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HAMSTERS

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Enteritis is another common hamster disease, primarily affecting the gastrointestinal tract.5,7 Commonly called "wet tail", this disease can be caused by the bacterium lawsonia intracellularis, clostridium sp., and/or helicobacter. Wet tail is generally unresponsive to treatment, and there is no known cure for enteritis caused by an infection with lawsonia sp. Hamsters, usually the very old, can also be prone to develop neoplasms, lymphoma and leukemia.5

GERBILS

Gerbils are not very commonly used in biomedical research, but do have distinct features that make them of interest. About 20% of the gerbil population is genetically predisposed to seizures. There is no treatment or cure for this disorder, and genetically altered gerbils are now available including seizure-sensitive and seizure-resistant strains. Gerbils are also susceptible to a bacterial infection known as Tyzzer's disease, which is a naturally occurring enteropathic disease.7 This disease is very acute and can often be fatal, causing liver necrosis an