Database of 4 million race starts enables major study of Thoroughbred sudden death
31 Oct 2022
The first study ever made on a large scale of sudden death in Thoroughbred race horses has suggested a commonly employed drug could be a potential increased risk factor.
Published in the Journal of the American Veterinary Medicine Association, the study examined data from 4 million horse racing starts in the USA and Canada over 12 years.
It identified that a small but significant minority of cases – 10,000 in all – resulted in the death of a Thoroughbred.
Among the "potential" risk factors the research cited was the drug fFurosemide. Administered to 94% of Thoroughbreds in the study, it is employed to prevent exercise-induced pulmonary haemorrhage or bleeding in the airways.
The study claimed that horses who had been administered the drug appeared to have a 62% greater chance of sudden death than those who had not been.
Dr Euan Bennet, Lecturer in Research and Numerical Skills at the School of Biodiversity, One Health and Veterinary Medicine at the University of Glasgow, which led the research, said:
“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.”
While furosemide is restricted or even prohibited on race day in some jurisdictions, Dr Bennet stated that discussion around the ethics of race day administration of drugs should factor in its potential effect. However he cautioned that further work was required “to understand exactly why we identified this association”.
Thoroughbreds constitute a specific breed of horse, developed from English mares and Arab and West Asian stallions in the 17th and 18th centuries to produce animals physically and temperamentally suited for competitive sports, especially horse racing.
However, the breed is associated with high rates of internal bleeding, low hoof to body mass ratios and a high rate of accidents.
The study – completed with University of Bristol Veterinary School Professor Tim Parkin, was funded by the Grayson Jockey Club Foundation and accessed data from the North American Equine Injury Database (EID) – suggested the possibility of identifying those animals most at risk and limiting fatalities, say the researchers.
Said Bennet: “Over the last 12 years, the overall risk of fatality within three days of racing has decreased by over 30%, but the incidence rate of sudden deaths has not changed significantly.
“This suggests that while interventions have been made which have contributed to a reduction in catastrophic injury, there are different sources of risk for sudden death which have not yet been identified.
The rarity of sudden death incidents, however, meant more research would be needed to pinpoint effective interventions, he cautioned.
To read more about the research, Fifteen risk factors associated with sudden death in Thoroughbred racehorses in North America (2009-2021), published in the Journal of the American Veterinary Medicine Association click here.
