Veterinarians and researchers are on an ongoing mission to reduce the number of racehorse injuries and deaths during racing and training. Key to achieving that is documenting and scrutinizing the incidents that do occur to look for trends that could lead to answers.
Researchers in Ontario, Canada, recently completed a retrospective study of racehorse post-mortem reports submitted to the Ontario Racing Commission (now the Alcohol and Gaming Commission of Ontario) Death Registry over a 13-year period.
“It is important to document the exact numbers of horses that succumb to these conditions in order to target further research to identify preventive measures,” said Josepha DeLay, DVM, DVSc, Dipl. ACVP, a veterinary pathologist at the University of Guelph’s Animal Health Laboratory.
Ontario is unique in that its racing population includes significant numbers of both Thoroughbreds and Standardbreds, as well as Quarter Horses.
“The benefit of this diverse racehorse population is the ability to provide information to the racing industry on the cause of death among each breed and to directly compare findings between these populations,” DeLay said.
In her study, DeLay reviewed 963 post-mortem records. Some of her key findings included:
- 68% of deaths associated with racing or training resulted from musculoskeletal injury, such as bone fracture or tendon or ligament injury;
- The most common injury in Thoroughbreds was to the forelimb fetlock and pastern fractures were most common in Standardbreds; there were too few Quarter Horses with fractures to allow identification of any anatomic sites predisposed to fracture, DeLay said.
- Sudden death accounted for 31%% of all exercise-associated reported deaths;
- Miscellaneous conditions that led to euthanasia while exercising was only 1%;
- Pulmonary hemorrhage was a common postmortem finding in both Standardbreds and Thoroughbreds that died while exercising, but occurred most frequently in Standardbreds. There were too few exercise-related Quarter Horse deaths in the study group to identify any trends.
DeLay said sudden death remains an active study area. Notes made on necropsy suggested that many of these horses had lung and/or heart lesions.
While veterinarians speculate that cardiac arrhythmia could have contributed to these sudden deaths, “until we know the exact cause of death in these horses, it is difficult to prevent this tragic outcome,” DeLay said.
She hopes these study results will help veterinarians, veterinary pathologists, and racing officials who are working toward the common goal of improving racehorse health and welfare.
The study, “Postmortem findings in Ontario racehorses, 2003-2015,” was published in the Journal of Veterinary Diagnostic Investigation.