12/16/2013 2:25PM

Breeders' Cup furosemide study raises questions

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A study examining juveniles that raced on the Nov. 1 and 2 Breeders’ Cup cards at Santa Anita has contradicted a previous study showing that the legal raceday medication furosemide is effective in mitigating the incidence and severity of bleeding.

The study last month, which entailed the endoscopic examination of 41 horses that raced without furosemide and 14 horses that raced on the medication, showed that horses treated with the drug had a statistically significant higher incidence and severity of bleeding than the untreated horses. A 2009 study on horses running in South Africa, which was conducted in a more scientifically rigid manner, showed just the opposite, confirming what some horsemen see as anecdotal evidence for the efficacy of the drug in mitigating bleeding.

Though the authors of last month’s study cautioned that the study’s limitations make the interpretation of the results difficult, the findings are sure to inflame an already contentious debate on the use of raceday furosemide, which is legal in all North American racing jurisdictions but prohibited in most other major racing countries worldwide. Supporters of furosemide use have said that the drug is an effective treatment for bleeding in the lungs, while critics have said the drug’s efficacy is vastly overstated and that the use of the drug on raceday in North America is exacerbating the sport’s public-perception problems.

The study, which was paid for by Breeders’ Cup, examined a total of 55 horses that raced during the two Breeders’ Cup cards. Juveniles running in the five Breeders’ Cup races for 2-year-olds were prohibited from running on furosemide under a rule that was allowed to expire this year, while horses in two non-Breeders’ Cup races, for California-bred juveniles, were allowed to race on the drug.

According to the study, 15 of the 41 untreated horses showed evidence of bleeding, or 37 percent, while 10 of the 14 treated horses, or 71 percent, showed evidence of bleeding (any fleck of blood visible on endoscopic examination of the trachea, the tube running from the lungs to the nose and mouth).

The study also found that five of the 14 horses, or 36 percent, treated with Lasix were scored as having bled in the higher ranges of the scale, compared with only three of the 44 untreated horses, or 7 percent. That result strongly contradicted the South Africa study, which found that horses treated with furosemide were far less likely to suffer “severe episodes of bleeding” than those injected with a saline solution.

Veterinarian Nathan Slovis, who oversaw last month’s study, said on a conference call that he had expected to find that the treated horses had lower incidences of bleeding, along the lines of the South Africa study. He cautioned that the Breeders’ Cup study looked only at “the best of the best,” and said that the South Africa study and the Breeders’ Cup study were “apples and oranges.”

“You cannot correlate our study to the South Africa one,” he said, acknowledging that the South Africa study had far fewer limitations. “You cannot compare the two.”

When asked why the result appeared to so strongly contradict the South Africa study, Slovis said that the Breeders’ Cup study had a built-in selection bias because owners of the horses that raced without furosemide knew beforehand the drug would be prohibited in the Breeders’ Cup races and may not have run horses that were bleeders.

Alternately, the horses running in the two Cal-bred stakes races included in the study “may be the horses that needed it,” Slovis said.
“It may be the caliber of the horse, different training methods, different environmental factors, it could be any number of factors,” Slovis said.

Breeders’ Cup decided to undertake the study after the Breeders’ Cup board, in a controversial vote, decided earlier in the year to suspend the ban on the drug because of concerns that horsemen would withhold approval of wagering on the Breeders’ Cup simulcast signal if the ban was not rescinded for 2014. Horsemen’s groups are the most ardent supporters of raceday use of the drug.

Craig Fravel, the chief executive of Breeders’ Cup, said the results “pose more questions than answers” and he said that the issue of raceday furosemide requires more study. He called on other industry organizations to support more research.

The question of whether furosemide is truly effective in mitigating bleeding is not the only mystery surrounding the drug. While some have theorized that the drug, a diuretic most commonly known by its former trade name, Lasix, could be effective by decreasing blood pressure in the lungs, the means of its efficacy is unknown.

“We really don’t have any data on how Lasix works,” said David Richardson, a Breeders’ Cup director and the chief of surgery at the University of Louisville. “You can also argue that we need a little more basic science … and what the side effects are.”