Equine Pharmacology
Equine Pharmacology Editors Cynthia Cole DVM, PhD, DACVCP Director of Research & Development, Mars Veterinary, Portland, Oregon, USA Bradford Bentz VMD, MS, DACVIM, DACVECC, DABVP (equine) Equine Medicine and Surgery, Bossier City, Louisiana, USA Lara Maxwell DVM, PhD, DACVCP Oklahoma State University, Stillwater, Oklahoma, USA
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Contents Contributors, vi Preface, viii Section 1: General Review Section 1 Horse of a different color: Peculiarities of equine pharmacology, 3 Lara Maxwell 2 Basics of antimicrobial therapy for the horse, 16 Cynthia Cole 3 Anesthesia and sedation in the field, 44 Jennifer E. Carter 4 Clinical application of equine analgesics, 63 Sheilah A. Robertson and L. Chris Sanchez 5 Pharmacology of nonsteroidal anti-inflammatory drugs, 76 Cynthia Cole 6 Parasiticides for use in horses, 85 Tad Coles and Randy Lynn 7 Foals are not just mini horses, 99 K. Gary Magdesian 8 Fluids and electrolytes for the equine clinician, 118 Brett Tennent-Brown 9 Drug and medication control programs in equine athletes, 131 Scot Waterman and Jennifer Durenburger Section 2: Therapeutics: A Systems Approach 10 Clinical pharmacology of the respiratory system, 139 Melissa R. Mazan and Michelle L. Ceresia 11 Clinical application of gastrointestinal therapeutics, 183 L. Chris Sanchez 12 Treatment of equine nervous system disorders, 192 Cynthia Cole and Bradford Bentz 13 Clinical pharmacology of the equine musculoskeletal system, 218 Bradford Bentz 14 Therapy of the eye, 254 Amber Labelle 15 Pharmacological treatment of equine endocrine diseases, 270 Dianne McFarlane 16 Equine cardiovascular clinical pharmacology, 279 Meg Sleeper 17 Clinical pharmacology of diseases of the equine urinary system, 291 Nora Nogradi and Balazs Toth Index, 308 v
Contributors Bradford Bentz, VMD, MS, DACVIM, DACVECC, DABVP (equine) Equine Medicine and Surgery Bossier City, LA, USA Jennifer E. Carter, DVM, MANZCVS, DACVAA, CVPP Lecturer in Veterinary Anaesthesia Faculty of Veterinary Science University of Melbourne Werribee, Australia Michelle L. Ceresia, PharmD MCPHS University Boston, MA, USA Cynthia Cole, DVM, PhD, DACVCP Director of Research & Development Mars Veterinary Portland, OR, USA Tad Coles, DVM Kansas City, MO, USA Jennifer Durenburger, DVM, JD Director of Racing Massachusetts Gaming Commission Boston, MA, USA Amber Labelle, DVM, MS, DACVO Assistant Professor Comparative Ophthalmology Veterinary Teaching Hospital University of Illinois Urbana-Champaign Urbana, IL, USA Randy Lynn, DVM, MS, DACVCP Greensboro, NC, USA Dianne McFarlane, DVM, PhD, DACVIM, ABVP /Ricks-Rapp Professor Oklahoma State University Stillwater, OK, USA Lara Maxwell, DVM, PhD, DACVCP Oklahoma State University Stillwater, OK, USA Melissa R. Mazan, DVM, Diplomate ACVIM Department of Clinical Sciences Cummings School of Veterinary Medicine Tufts University North Grafton, MA, USA Nora Nogradi, DVM, DACVIM Equine Internal Medicine Specialist Dubai Equine Hospital Dubai, United Arab Emirates Sheilah A. Robertson, BVMS (Hons), PhD, DECVAA, DACVAA, Dip ECAWBM (WSEL) Specialist in Welfare Science, Ethics and Law, DACAW, MRCVS Professor Department of Large Animal Clinical Sciences University of Florida College of Veterinary Medicine Gainesville, FL, USA L. Chris Sanchez, DVM, PhD, DACVIM Department of Large Animal Clinical Sciences University of Florida College of Veterinary Medicine Gainesville, FL, USA K. Gary Magdesian, DVM, DACVIM, ACVCP, ACVECC Henry Endowed Chair in Emergency Medicine and Critical Care School of Veterinary Medicine University of California Davis, CA, USA Meg Sleeper, VMD, DACVIM (Cardiology) of Cardiology/Clinician Educator School of Veterinary Medicine University of Pennsylvania Philadelphia, PA, USA vi
Contributors vii Brett Tennent-Brown, BVSc, MS, DACVIM, DACVECC The University of Melbourne Hawthorn, Victoria, Australia Balazs Toth, DVM, MS, MSc, DACVIM Section Head Equine Internal Medicine Equine Department and Clinic Szent István University Dora-Major, Hungary Scot Waterman, DVM Animal Welfare and Medical Advisor Arizona Department of Racing Tucson, AZ, USA
Preface The objective of this book is to provide practitioners and veterinary students with a concise and practical guide to equine clinical pharmacology. Although some equine pharmacology texts choose to emphasize complete in-depth reviews of the scientific literature, this approach does not necessarily help the practitioner choose the best therapeutic approach for a specific clinical situation. In contrast, whereas formulary texts are extremely popular for their ease of use and simplicity, there is much more to the successful use of therapeutic medications in horses than simply choosing a dose and dosing frequency. Therefore, we sought authors for this book who are both experts in the specific topic of interest and also had experience or interest in clinical pharmacology. Because we wanted the text to be very practical with a clinical approach, we sought individuals who deal with medication issues on a regular basis, either in their patients in the clinics, in the course of their research, or in many cases a combination of both. The text is divided into two sections. Section 1 begins with a discussion of some of the important differences between horses and other species in terms of clinical pharmacology. This is an extremely important chapter because many of the therapeutics used in horses have not been well studied and their potential benefits and risks are extrapolated from studies in other species. Practitioners need to be aware of the limitations and caveats of such extrapolations. This section also covers a broad range of clinical pharmacology topics that commonly confront the equine practitioner, including antimicrobials, anesthesia, analgesics, nonsteroidal antiinflammatory drugs (NSAIDs), and anti-parasiticides. A separate chapter on the clinical pharmacology of foals was included to stress how their unique physiology has ramifications in the use of therapeutics in neonates. Although fluids and electrolytes are not uniformly considered to be within the realm of clinical pharmacology, we included a chapter on this topic because fluids and electrolyte balance are critical components of many therapeutic plans for critically ill horses. Finally, a discussion of drug and medication control programs was included because most equine athletes compete under such regulations, so it is important for practitioners to know where they can get accurate, up-to-date information on those rules. Section 2 takes a systems approach to clinical pharmacology. Often pharmacology is presented by drug classes, but rarely is only a single class of drugs indicated in the treatment of a disease condition. By discussing therapeutic approaches for diseases that affect each organ system, a concise, logical, and comprehensive guide is provided to the practitioner. The systems covered range from the ophthalmic to cardiovascular. Because the same drug may be used in the therapy of several different diseases, therapeutics may appear in multiple chapters. For example, the use of NSAIDs is discussed in a summary chapter in Section 1 but are also included in several chapters in Section 2. viii