A comprehensive post-mortem survey in Victoria, Australia, found that euthanasia for catastrophic forelimb injury was the most common cause of Thoroughbred racehorse fatality. Additionally, Lisa Boden, AB, BVSc, MACVS, of The University of Melbourne in Australia, observed that sudden death (when the horse dies suddenly–not as the result of euthanasia) was a more important contributor to Victorian racing fatalities than previously thought. She presented the study data at the 2005 American Association of Equine Practitioners’ Convention on Dec. 6 in Seattle, Wash., and she suggested that analyzing point-of-death blood samples could help veterinarians better pinpoint the potential triggers of sudden deaths.

Boden and her colleagues thoroughly documented injuries that either caused sudden death or required euthanasia of racehorses (within 24 hours of a catastrophic injury) during the three-year prospective study. Metropolitan racetracks in Victoria were required to submit all affected horses for post mortem examination, and veterinarians at country tracks could elect to submit cadavers as well.

Seventy-seven racehorse cadavers were submitted and represented 43% of the 180 racing deaths in Victoria over the study period. Of those 77 horses, 61 (79%) were from the metropolitan tracks and 16 (21%) were from country racecourses. Thirty-one fatal injuries (40%) were sustained in flat races, 25 (32%) in track or non-raceday events, 19 (25%) in jump races (hurdle and steeplechase events), and two in barrier trials (qualifiers, 3%). Fifty-two of the horses were euthanatized and the remaining 25 died suddenly without veterinary assistance (they were not euthanatized).

Most of the horses submitted were males (61, or 79%), and of those, 56 were geldings (92% of the males). The age of affected horses ranged from two to 10 years with a mean of 5.2 years. The mean age of females was four years and the mean age of males was 5.5 ye