10 September 1999


by Kate Melville

A drug given before a race to horses for a certain medical condition is suspected of having a positive effect on their performance. The drug, furosemide, is given to racehorses with a history of bleeding in the respiratory tract. Furosemide is one of the only drugs allowed in all racing jurisdictions in the United States and Canada but it is banned in most other racing jurisdictions in the world.

During the 1980s, controversy arose surrounding the use of furosemide as a preventive measure for respiratory bleeding. Researchers aren't sure if furosemide has an effect on respiratory bleeding, but for nearly 30 years, thoroughbred trainers and owners in the USA (and probably elsewhere) have used furosemide to treat the disorder.

According to Associate Professor Kenneth Hinchcliff, of Ohio State, "We've found excellent evidence that associates furosemide with better performance." Although Hinchcliff and his colleagues stopped short, of saying that the drug definitively improves performance.

Hinchcliff 's team analysed the race records of 22,589 thoroughbreds, the researchers found that 74 percent (16,761) of the horses were given furosemide prior to a race.

These horses raced faster, were 1.4 times more likely to win a race, 1.2 times more likely to finish in the top three and earned an average of $416.00 more than the horses not receiving the drug. While 85 percent of the horses in the study had received furosemide at some point in their lives, about 74 percent of thoroughbreds are likely to be running on the drug during a race, Gross said.

The trade name for furosemide is Lasix and it is according to one team member, "frequently used by humans for its diuretic effects" (the editor wonders if this may be an oblique reference to jockeys)? In any case the diuretic effect may cause enhanced racing performance, and other studies found that horses on furosemide lost about 20 pounds of their pre-race body weight through urination. And if weight can affect performance, a horse that's lost 20 pounds would theoretically have a racing advantage.