Common racehorse drug could raise risk of sudden death
The scientists identified a significant risk factor associated with horses being given furosemide on race day.
Researchers have discovered that a common drug used in Thoroughbred racehorses could increase the risk of sudden death.
The first-of-its-kind study analysing data from more than four million starts in horse racing across the USA and Canada found that around one in 10,000 resulted in a race-day sudden death.
Scientists identified a significant risk factor associated with the horses being given furosemide on race day. Horses given the drug were 62 per cent more likely to die suddenly, when compared with horses not given furosemide.
Furosemide is widely used in the US on race days to prevent pulmonary bleeding and is associated with enhanced racing performance. Consequently, 94 per cent of horse starts in the study had been administered with the drug.
Scientists discovered that it could also be possible to identify horses at risk of sudden death before they experience it – for example, due to previous injury and interruption to training. Other risk factors highlighted by the study were horse age and sex, season, purse of race and race distance.
Study author Dr Euan Bennet, from the University of Glasgow's School of Biodiversity, One Health and Veterinary Medicine, commented: “This study suggests that a risk profile, identifying which horses are at the greatest risk of sudden death, may be possible. Given how rare the outcome is, further work is required to establish any potential interventions which might contribute to a reduction in sudden deaths.
“On the association between furosemide use and sudden death, the fact that furosemide use is so common makes this result particularly remarkable given the statistical power of this large-scale study. Discussions around the ethics of race day administration of drugs should factor in potential risks such as those identified here, and further work is required to understand exactly why we identified this association.”
The study, ‘Fifteen risk factors associated with sudden death in Thoroughbred racehorses in North America (2009-2021),’ is published in the Journal of the American Veterinary Medicine Association.
The BSAVA has opened submissions for the BSAVA Clinical Research Abstracts 2026.
