10/29/2014 6:06PM

Lasix studies reveal moderate bleeders remain competitive with non-bleeders


A researcher at Colorado State University who has collaborated on influential research on the anti-bleeding medication furosemide has released the results of three new studies claiming that bleeding is detrimental to performance but that moderate forms of the condition do not have appear to have a negative impact on a horse’s ability to earn purse money.

The first study, whose lead author was Dr. Paul Morley, of the Colorado State University College of Veterinary Medicine, examined 1,000 horses that raced in South Africa. All of the horses received tracheal exams following a race, with researchers scoring the severity of bleeding.

According to the study, horses that did not bleed were twice as likely to win races than those that did bleed, while finishing an average of one length ahead of horses that bled. In addition, those horses that did not bleed were 2.5 times more likely to be in the highest decile of purse earners among the population.

The second study, however, appeared to at least subtly contradict the results of the first. In the study, Morley and his collaborators, including Dr. Stacey Sullivan of the University of Melbourne, examined the career racing results of 744 horses that were examined for bleeding in the lungs in Australia in 2003. The examination found that horses that did not bleed and horses that bled only moderately did not differ appreciably in the number of races in their careers or in the total amount of purse money earned.

Those horses that bled severely, however, had “impaired long-term race performance.” Severe bleeding is usually associated with a large amount of visible blood in the trachea, which is believed to hinder breathing.

The study’s authors also cautioned that the results were gleaned from the scoring of a single post-race tracheal examination of the horses used in the study. 

The third study, which was an analysis of previous scientific studies, appeared to confirm that furosemide, which is legal to administer on race day in the United States  and Canada and is commonly known by the trade name Lasix,, is effective in reducing the severity and frequency of bleeding in the lungs, the study says. The study concluded that there is “high-quality, albeit limited evidence” of the effectiveness of furosemide based on the results of 17 studies that fit the criteria of the analysis.

Morley was a collaborator on a 2009 study examining furosemide and bleeding in South African racehorses that reached the same conclusion. The 2009 study, which was funded in part by North American racing groups, has been cited by U.S. horsemen as providing scientific evidence for continuing to allow the drug to be administered on race day, despite its ban in most other major racing jurisdictions worldwide.

Use of furosemide on race day has been one of the most controversial issues in U.S. racing over the past four years. A number of organizations, including the Jockey Club and the Breeders’ Cup, have attempted to build support for a rollback on the legality of the medication on race day, but those efforts have largely failed due to the opposition of most horsemen’s groups and a reluctance by state racing commissions to restrict race day use of the medication.

“These studies build on our earlier work to provide horsemen and regulators with the evidence they need to inform the highly charged debate about [bleeding] and Lasix,” said one of the study’s co-authors, Dr. Kenneth Hinchcliff of the University of Melbourne, in a release distributed by Colorado State University. “Our international team has explicitly addressed the key issues facing racing around the management of [bleeding].”

 Hinchcliff was also a co-author of the 2009 study of South African horses.