The Horse:Your Guide To Equine Health Care provides monthly equine health care information to horse owners, breeders, veterinarians, barn/farm managers, trainer/riding instructors, and others involved in the hands-on care of the horse.
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44 TheHorse.com THE HORSE October 2015 I t is one of the biggest mysteries in equestrian sport, and its name alone is ominous: sudden death. While cases are very rare and totally unpredictable, the effects of just one horse collaps- ing suddenly and dying, often in the midst of a competition with thousands of spectators, are far-reaching: Most instances, which can be very upsetting to witness, attract media attention and public scrutiny of equine welfare, and an investigation into the horse's death can shed negative light on equestrian sports, whether deserved or not. Often, sudden death occurs at the top levels of the sport in what appear to be the healthiest of horses—mounts that have been monitored closely and main- tained with the best of care. In November 2011, the death of 2008 Olympic Individ- ual Gold and Team Silver medal winner Hickstead, during a show jumping event in Verona, Italy, shocked witnesses while devastating all those involved with the horse, including his rider, Eric Lamaze. The 15-year-old Dutch Warmblood stal- lion had just finished an almost perfect course. Veterinarians later determined that he had suffered a ruptured aorta. Sudden death has occurred in nearly all equine sports, but the most frequent and attention-getting cases typically involve an event horse or a racehorse. Of- ten, the media reports the cause of death as a "heart attack," which is inaccurate. Peter Physick-Sheard, BVSc, FRCVS, associate professor at the University of Guelph, in Ontario, has a special inter- est in equine cardiology, and he and his colleague, Kim McGurrin, DVM, DVSc, Dipl. ACVIM, have studied sudden death in horses. Physick-Sheard explains that horses do not suffer heart attacks like hu- mans do because they are free of serious disease of the coronary arteries. Rikke Buhl, DVM, PhD, professor and section head of Medicine and Surgery in Large Animal Internal Medicine at the University of Copenhagen, in Denmark, is one of the world's leading experts in equine cardiology. "The most important message is that we don't really know why these horses die, but research groups all over the world are trying to elucidate these tragic events," she says. Causes and Frequency Physick-Sheard says that some of the most important things for the lay public to understand about sudden death are that it is rare, it only happens with any frequency in young racehorses, and that people need to use a standard terminol- ogy for discussing it. He defines it as "the sudden unexpected death of a horse that has shown no previ- ous signs of a potentially life- threatening condition and in which post-mortem examination reveals no adequate expla- nation," whereas others' definitions do not include the part about post- mortem exams. He says these differences in defining the condition make it difficult to determine how many cases should truly be considered "sudden death." Buhl adds, "Sudden death also occurs when horses are at their private training yards with no public witnesses, so these events are not included in any registra- tions (records). Therefore, the exact number of cases is not known today." In a previous study (TheHorse. com/27151), Catriona Lyle, RCVS, of the University of Edinburgh's Royal School of Veterinary Studies, in Scotland, looked at cause of death in 268 cases of sudden death in Thoroughbred racehorses from California, Pennsylvania, Australia (Victo- ria and Sydney), Hong Kong, and Japan. On post-mortem examinations, research- ers identified cardiac failure, presumptive pulmonary (lung) failure, pulmonary hemorrhage, hemorrhage associated with pelvic fractures and blood vessel rupture, and spinal cord injury. Only 53% of the deaths had a definitive cause, 25% had a presumptive cause, and 22% were SPORTS MEDICINE SARAH EVERS CONRAD TheHorse.com/Sports-Medicine When the Heart of a Champion Gives Out We don't yet know why some horses die suddenly during competition, so research groups around the world are studying these tragic events. ARND BRONKHORST Researchers are trying to determine why healthy equine athletes suffer sudden death and if there's a way to prevent it