Ontario Racehorse Deaths

This descriptive study examined the frequency of racehorse deaths in Ontario, Canada, from 2003 through 2015. In 2003, the Ontario Racing Commission created a reporting system to record all deaths of Thoroughbred, Quarter Horse and Standardbred racehorses that occurred within 60 days of racing or entering a race or timed work. Owners are required to report all deaths that occur regardless of the cause or where the death occurred.

Differences were detected between breeds. Thoroughbreds had the greatest exercise associated mortality with 2.3 deaths per 1,000 race starts (1% annual individual risk) compared with Quarter Horses with 1.49 deaths/1,000 starts (0.7% annual risk) and Standardbreds with 0.3 deaths/1,000 starts (0.24% annual risk). These rates were consistent from year to year, with the exception of a year when about three deaths from 1,000 starts occurred among Quarter Horses.

Most deaths were related to musculoskeletal causes with high- speed training and racing identified as the most risky activities. About 35% of the musculoskeletal deaths occurred during training for Thoroughbreds with much fewer training deaths occurring in the other breeds. Sudden death and colic were the next most common causes of death followed by iatrogenic causes including adverse reactions to medications and joint infections secondary to injections.

Interestingly, this study found non-exercise related annual risk was higher for Standardbreds than for Thoroughbreds or Quarter Horses.

— Physick-Sheard P et al. EVJ 2019;51:64-76

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