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.