Drug Increases Risk of Sudden Death in Racehorses

A drug that has been widely used in Thoroughbred racehorses in North America could increase the risk of sudden death, according to a new study. The research also identified other risk factors associated with sudden death, relating to the circumstances of the race and individual histories of the horses. 

The research, conducted by Dr. Euan Bennett of the University of Glasgow’s School of Biodiversity, One Health & Veterinary Medicine, and Professor Tim Parkin of the University of Bristol Vet School, is the first large-scale study of sudden death in Thoroughbred racehorses. 

The work was funded by the Grayson Jockey Club Foundation. A report is published in the Journal of the American Veterinary Medical Association. 

The study analysed over four million starts in horse racing over a 12-year period, using data recorded in the Equine Injury Database (EID), which contains details of nearly all official race starts made in the United States and Canada. About one in 10,000 race starts resulted in a racing-related sudden death for a horse. 

For this study, “sudden death” was taken to include any fatality occurring within three days of racing where the cause of death recorded in the EID was sudden death, pulmonary haemorrhage, exercise-induced pulmonary haemorrhage (EIPH), post-exertional distress/heatstroke (PED), or cardiac arrhythmia. Fatalities due to catastrophic musculoskeletal injury were not included.

The researchers identified a notable risk factor related to race day medication. Horses that were recorded as being administered furosemide were 62 percent more likely to experience sudden death compared to horses that weren’t on furosemide.