FEI Debates Use of NSAIDs in Competing Horses

The most commonly used non-steroidal anti-inflammatory drugs (NSAIDs) in equine medicine are relatively safe, effective, and short-lived at low doses, but their use could mask lameness or other ailments in competing horses, according to international scientists at the recent NSAIDs congress hosted by the Fédération Equestre Internationale (FEI).

Whether NSAIDs should be allowed in competition is a current issue of debate among FEI member organizations--primarily national federations. To assist in this debate, leading pharmacologists, toxicologists, and equine veterinarians presented scientific data on the mechanisms, dosing, and possible effects and consequences of NSAID use to the congress audience in Lausanne, Switzerland, in August.

NSAIDs work primarily by regulating inflammatory mediator enzymes called cyclooxygenases, according to Colin Roberts, BVSc, PhD, FRCVS, veterinary consultant to the Animal Health Trust in Newmarket, England, and member of the FEI medication control panel. The cyclooxygenases can be subdivided into two categories: COX-1, which help maintain normal physiological function, and COX-2, which are more directly responsible for inflammation. "There has been a lot of work in creating NSAIDs that selectively affect the COX-2 enzymes and leave the COX-1 enzymes alone," to minimize adverse effects, Roberts said.

In some horses--particularly young or diseased animals--NSAIDs might negatively affect the kidneys, gastrointestinal system, or liver and could impair the clotting function of the blood, according to Johanna Fink-Gremmels, DVM, PhD, Dipl. ECVPT, professor in the veterinary pharmacology, pharmacy, and toxicology division of the equine clinic at the University of Utrecht, Germany. Although NSAIDs have an "appreciable margin of safety," the risks are increased with long-term use, she said.

Currently the most common NSAIDs used in horses are phenylbutazone (bute) and flunixin meglumine (Banamine), which do not selectively affect specific cyclooxygenase enzymes, according to Wayne McIlwraith, DVM, BVSc, FRCVS, PhD, Dipl. ACVS, Dipl. ECVS, professor of surgery and university chair of equine orthopedic research at Colorado State University.

The individual use of these two NSAIDs is considered safe enough to be allowed up to 12 hours prior to competition by some national federations, including the United States, according to Jon Foreman, DVM, MS, Dipl. ACVIM, associate dean at the University of Illinois, FEI veterinary official, and member of the emergency veterinary staff for the 2010 Alltech FEI World Equestrian Games. Used simultaneously, however, the two-drug combination has been shown to cause "substantially greater toxicity," including gastric ulcers and death.

At normal doses (4.4 mg/kg/day), phenylbutazone improves lameness and reduces joint temperature for two to 10 hours, McIlwraith said. Increased doses do not seem to make the drug more effective against pain, but the effects appear to last longer. Flunixin's analgesic effects can last up to 30 hours despite its short half-life, probably because it quickly accumulates in inflammatory tissue, he said.

Studies on NSAID use and performance are limited, but initial results indicate the use of NSAIDs neither enhance nor impair performance, according to Kenneth Hinchcliff, BVSc, MS, PhD, Dipl. ACVIM, dean of the faculty of veterinary science at the University of Melbourne, Australia.

Half-doses would probably help improve lameness somewhat and for a very limited time, Foreman said. This might satisfy a suggested proposal that NSAIDs be allowed up to 12 hours before competing and could benefit the welfare of horses suffering from "mild sorenesses which are not performance-limiting." However, allowing their use during competitions could result in lame horses competing and would also go against the "level playing field" concept, Foreman added. "Based on (racing) data, permitting the use of NSAIDs during competition may have a negative impact on the safety of the horse and rider," he said.

The recently published proposal of the FEI List Group suggests that more research on phenylbutazone and flunixin be carried out to reveal specific detection times. A detection time is the amount of time it takes for the concentration of the drug in blood or urine to be lower than the established limit set to indicate a positive test in routine screening, according to Pierre-Louis Toutain, PhD, DVM, professor of physiology and therapeutics at the National Veterinary School of Toulouse, France. However, because all horses process NSAIDs differently, the recommended time to stop administering the drug prior to a competition--called the withdrawal time--should take these differences into consideration. "A detection time is a raw experimental observation, whereas a withdrawal time is a recommendation and, as such, is a matter for the professional judgment of the treating veterinarian," he said.

The full presentations of all 13 scientific speakers at the NSAIDS congress as well as the three related panel discussions are now available for video viewing at the FEI website.

Representatives from national federations will vote on the use of NSAIDs in competition horses during the General Assembly of the FEI, to be held in Chinese Tapei in November.

About the Author

Christa Lesté-Lasserre, MA

Christa Lesté-Lasserre is a freelance writer based in France. A native of Dallas, Texas, Lesté-Lasserre grew up riding Quarter Horses, Appaloosas, and Shetland Ponies. She holds a master’s degree in English, specializing in creative writing, from the University of Mississippi in Oxford and earned a bachelor's in journalism and creative writing with a minor in sciences from Baylor University in Waco, Texas. She currently keeps her two Trakehners at home near Paris. Follow Lesté-Lasserre on Twitter @christalestelas.

Stay on top of the most recent Horse Health news with FREE weekly newsletters from TheHorse.com. Learn More