OBJECTIVE: To evaluate the efficacy of furosemide for prevention of exercise-induced pulmonary
hemorrhage (EIPH) in Thoroughbred racehorses under typical racing conditions.
DESIGN: Randomized, placebo-controlled, blinded, crossover field trial.
ANIMALS: 167 Thoroughbred racehorses.
PROCEDURES: Horses were allocated to race fields of 9 to 16 horses each and raced twice,
1 week apart, with each of the 2 races consisting of the same race field and distance. Each
horse received furosemide (500 mg, IV) before one race and a placebo (saline solution)
before the other, with the order of treatments randomly determined. Severity of EIPH was
scored on a scale from 0 to 4 after each race by means of tracheobronchoscopy. Data were
analyzed by means of various methods of multivariable logistic regression.
RESULTS: Horses were substantially more likely to develop EIPH (severity score ≥ 1; odds
ratio, 3.3 to 4.4) or moderate to severe EIPH (severity score ≥ 2; odds ratio, 6.9 to 11.0)
following administration of saline solution than following administration of furosemide. In
addition, 81 of the 120 (67.5%) horses that had EIPH after administration of saline solution
had a reduction in EIPH severity score of at least 1 when treated with furosemide.
CONCLUSIONS AND CLINICAL RELAVANCE: Results indicated that prerace administration of
furosemide decreased the incidence and severity of EIPH in Thoroughbreds racing under
typical conditions in South Africa.