An article published in the current edition of the Journal of the American Veterinary Medical Association calls for more research into the association between Lasix use in racehorses and sudden death.
The article, “Fifteen risk factors associated with sudden death in thoroughbred racehorses in North America (2009-2021),” was written by Euan D. Bennet and Tim Parkin. The article is included in the October 20 edition of JAVMA.
Lasix (furosemide diuretic), approved for use on race day in North America to prevent or reduce the severity of exercise-induced pulmonary hemorrhage, was among 15 significantly associated risk factors to sudden death. It found that “horses racing while taking furosemide increased their rate of sudden death by 62%.”
When looking at those numbers in the study, the paper called for more research.
“The association between furosemide and sudden death prompts further studies to understand what biological processes may have contributed to this result,” the paper notes.
Under current drug regulations, most horses in the United States are allowed to race on Lasix, and the majority of trainers choose to treat their horses with medication. The most common exceptions of racehorses without it are 2-year-olds and staked competitors. Many racing jurisdictions prohibit the use of race-day Lasix on such horses.
The paper found that other factors associated with sudden death included the age and sex of the horse, race range, race distance, and the horse’s recent history of injury or hospitalization.
“The associations found between prior trauma and sudden death suggest that underlying pathology may be contributing in some cases,” the paper notes.
Salix, commonly known as Lasix
The study was based on the Jockey Club Equine Injury Database and Parkin is a veterinary epidemiologist who has been consulting on EID since its inception. Through an EID study, the industry has made a number of changes in various areas to help reduce catastrophic musculoskeletal injuries, which since 2009 have accounted for the majority of horse deaths during racing. .
While sudden deaths unrelated to musculoskeletal injuries account for only 7.4% of all fatal incidents, the industry has improved safety through a step-by-step process rather than a bullet. the silver. On the musculoskeletal side, this already includes changes to dosing rules, claims rules, out-of-pocket guidelines, and increased efforts to improve surface safety — just one few changes. Many of these changes were introduced to address the risk factors identified through the EID.
This step-by-step approach has helped racing reduce equine mortality by 30.5% since 2009. The 1.39 per 1,000 ratio starting in 2021 is a record low for the industry since 2009. 2009 when first started tracking rates. Another way to put this number is that in 2021, 99.86% of equine deaths will not occur.
Since these step-by-step changes have reduced musculoskeletal injuries, Parkin, head of the University of Bristol’s veterinary school, sees the potential to make further horse safety progress by addressing the small number of sudden death — non-musculoskeletal injury. Since 2009, these sudden deaths have occurred at a rate of 0.13 per 1,000 initiation cases. In June, at the Racehorse Safety and Welfare Summit in Keeneland | BloodHorse.com track record “>KeenelandParkin outlined some of the sudden death findings that appeared in the paper.
He noted that a number of senior horses have suffered sudden deaths in recent years, the matter having received more attention from the public. In December, Kentucky match winner eliminated by Woodford Reserve (G1), Medina Spirit died after training at Santa Anita . Park. The California Horse Racing Board later announced that a necropsy could not determine exactly why the 1st place winning foal collapsed and died after a practice session on December 6, but indicates results indicating acute heart failure that is not confirmed.
While neither CHRB nor Parkin addressed any link between Lasix use and Medina Spirit’s sudden death, it was one of two drugs in his system at the time of his death. . The CHRB reported that Omeprazole, an anti-ulcer drug, and Lasix were detected in blood and urine samples. These findings are consistent with a drug report submitted by the pony’s veterinarian to the CHRB.
Many horses are treated with Lasix before training from time to time.
In addition to the common sudden deaths, the EID numbers show no steady decline in sudden deaths as seen in musculoskeletal injury numbers since 2009. This has led to deaths, Parkin said. suddenly become a larger proportion of equine deaths. in racing — topping 10% of all horse racing deaths in the last few years.
“People are paying more attention to it on the track,” said Parkin, adding that compared to catastrophic incidents where the problem is obvious, it is not always clear what the exact cause of the problem is. deaths in horses listed in the sudden death category.
Parkin outlined the link between Lasix and sudden deaths revealed by EID.
“We identified for the first time a relationship between Lasix use in racehorses and sudden death,” says Parkin. “The use of Lasix during a race increases the risk by about 62%.”
Parkin acknowledges that even with regulatory changes in recent years that have seen more racehorses without a race day Lasix, the EID number is comparing a large number of horses racing on Lasix to some relatively small amounts of racehorses without diuretics. That said, he is confident that the EID numbers – which show horses racing with Lasix suffer sudden death at that rate 62% higher than racehorses without it – are statistically relevant. .
“I think there is evidence that there is some sort of physiological relationship, potentially, between Lasix use and sudden death,” Parkin said. “It definitely needs further investigation.”
Before the industry aggregated such information in EIDs, such relationships were elusive, Parkin said.
“I think the reason this hasn’t been identified before is purely statistical power,” says Parkin. “This is purely driven by the fact that we now have enough years of data — the starts and deaths in the database — to allow us to reach this conclusion.”
At the safety summit, Parkin said he’s looking forward to learning more about the effects of exercise or horse racing on Lasix, how it changes their blood chemistry, and perhaps contribute to the risk of cardiac arrhythmias.
