Exercise-induced pulmonary hemorrhage (EIPH), or bleeding into the airways, is an "extremely prevalent condition associated with high-intensity exercise in horses," according to Paul S. Morley, DVM, PhD, Dipl. ACVIM, professor of clinical sciences at Colorado State University. At the 2009 American Association of Equine Practitioners Convention, held Dec. 5-9 in Las Vegas, Nev., Morley discussed the landmark study he conducted on the effects of furosemide, marketed as Salix for horses (but also called Lasix in humans), with co-investigators Kenneth W. Hinchcliff, BVSc, PhD, Dipl. ACVIM, professor and Dean of the Faculty of Veterinary Science at the University of Melbourne, Australia; and Alan J. Guthrie, BVSc, PhD, Director of the Equine Research Centre at the University of Pretoria in South Africa.

The study’s impending publication in the Journal of the American Veterinary Medical Association (JAVMA) was announced in June 2009, at which point it gained massive attention even in non-horse media such as the New York Times. The study, previously discussed on TheHorse.com and published in the July 1, 2009, issue of JAVMA, unequivocally answered the question: Does furosemide reduce the incidence of EIPH in horses? The randomized, placebo-controlled, blinded, cross-over field trial proved beyond doubt that furosemide does reduce the incidence and severity of EIPH in racehorses.

Investigators found that giving furosemide before racing reduced a horse’s odds of having any EIPH at all by 3.3-4 times. As for EIPH severity, furosemide reduced a horse’s chances of bleeding at a grade 2 or higher level (shown to impair performance in previous research) by 6.9-11 times. Nearly 68% of horses that had EIPH when not on furosemide had at least one grade of improvement in their EIPH on furosemide.

A number of convention attendees participated in the question/answer session following the presentation, and the first question was probably the first on many minds: Did the horses run any faster on furosemide? The short answer was: We didn’t design the study to show that