Major study aims to answer key questions around race-day use of furosemide

Many US racehorses are given furosemide  before racing to help prevent bleeding into the lungs.
Many US racehorses are given furosemide before racing to help prevent bleeding into the lungs. Image by bianca-stock-photos

An American study that aims to address key unanswered questions around the race-day use of the drug furosemide is under way.

Race-day use of furosemide, or Lasix, and its effects has been a dominant issue confronting North American racing for more than a decade.

Many racehorses in the US are given furosemide a few hours before racing to reduce the risk of bleeding into the lungs.

However, it is a controversial treatment because there is evidence the drug may enhance performance because of its diuretic effect. Horses pass large amounts of urine in the hours following its use, meaning they can race at a lighter weight.

The study is being led by Dr Warwick Bayly and Dr Macarena Sanz, from the Department of Veterinary Clinical Services at Washington State University’s College of Veterinary Medicine.

It represents the largest study ever to focus on evaluating the effects of furosemide on two-year-old racehorses.

It aims to address the debate around whether the injection of furosemide has beneficial, detrimental or no effects on the welfare of these racehorses.

The study intends to address two key questions:

  • Does the administration of furosemide four hours before racing and/or training reduce the severity of bleeding into the lungs — formally known as exercise-induced pulmonary hemorrhage (EIPH) — in two-year-old racehorses?
  • Does the pre-race administration of furosemide four hours before racing affect a horse’s performance?

The study will evaluate the endoscopic exams from at least 600 horses from three groups representing the major racing jurisdictions of California, Delaware, Florida, Kentucky, Louisiana, Maryland, Pennsylvania, New Jersey and New York.

Horses will be evaluated in three groups. The first will comprise those who are given furosemide at least 48 hours before racing or not at all. The second will comprise those who are given furosemide 24 hours before racing or not at all. The third group will comprise only those horses who are given furosemide four hours before racing.

Veterinarians from each of the jurisdictions will be asked to recruit trainers who are existing clients to voluntarily participate in the study.

“This study provides an opportunity to fill a critical knowledge gap on the use of furosemide,” said Bayly, a professor in equine medicine who carried out previous research into EIPH.

“As a first-of-its-kind study of this depth, it is our hope that once completed we will be able to provide additional information that will enable the horse racing industry to address the regulation of furosemide in the United States from a scientifically informed perspective.”

Dr Dionne Benson, who is chief veterinary officer for The Stronach Group, a company with major horse-racing interests which is among organisations funding the study, said the current patchwork of rules and regulations across the United States around furosemide administration does a disservice to the horses and the practitioners who care for them.

“This study is an opportunity for industry stakeholders to come together to invest in meaningful steps to address pressing questions so that we may develop a higher and more consistent standard of rules and regulations.”

Dr Will Farmer, equine medical director for racing company Churchill Downs Incorporated, which is also backing the research, acknowledges that Lasix use has long been a highly debated topic.

“This is our opportunity, as advocates for the safety and welfare of our racehorses, to collect and analyze vital real-life information that can be used to help answer some questions regarding the use of Lasix and its effect, but also guide common-sense regulation around Lasix use.”

Keeneland, which runs the world’s largest Thoroughbred auction house, is also backing the research.

Its equine safety director, Dr Stuart Brown, said study the represents a unique collaboration of North American racing interests to further understand the true rate of EIPH in young racehorses through endoscopic examinations performed after races.

“The potential to gain insight under the present landscape of furosemide use across various racing jurisdictions will help shape decisions that benefit the safety and welfare of the equine athlete in competition.”

Preliminary results from the study are expected to be available in spring next year, assuming the quantity and quality of the samples satisfy the requirements for statistical relevance as set out by Bayly and Sanz.

The study, formally titled “Furosemide: Its Effects on the Prevalence and Severity of Exercise-Induced Pulmonary Hemorrhage (EIPH) and the Immune System’s Normal Response to Exercise in Two-Year-Old Racehorses,” is also supported financially by Breeders’ Cup Ltd, the Kentucky Horse Racing Commission, the Kentucky Thoroughbred Association and the New York Racing Association.

2 thoughts on “Major study aims to answer key questions around race-day use of furosemide

  • November 3, 2020 at 3:57 am

    Don’t they care about any long term effects on the horse’s health? Obviously not.

  • November 4, 2020 at 3:34 pm

    Why do it now? They waited 10 years. Why didn’t they do a study BEFORE the use of the drug?


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