Efficacy of furosemide for prevention of exercise-induced pulmonary hemorrhage in Thoroughbred racehorses

Kenneth W. Hinchcliff Faculty of Veterinary Science, University of Melbourne, Melbourne, VIC 3030, Australia.

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 BVSc, PhD, DACVIM
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Paul S. Morley Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523.

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 DVM, PhD, DACVIM
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Alan J. Guthrie Faculty of Veterinary Science, University of Pretoria, Onderstepoort 0110, Gauteng, Republic of South Africa.

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 BVSc, PhD
DOI:
https://doi.org/10.2460/javma.235.1.76
Volume/Issue:
Volume 235: Issue 1
Online Publication Date:
01 Jul 2009
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Abstract

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 Relevance—Results indicated that prerace administration of furosemide decreased the incidence and severity of EIPH in Thoroughbreds racing under typical conditions in South Africa.

Abstract

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 Relevance—Results indicated that prerace administration of furosemide decreased the incidence and severity of EIPH in Thoroughbreds racing under typical conditions in South Africa.

Contributor Notes

All authors contributed equally to this study.

Supported by the National Horseracing Authority of South Africa, Phumelela Gaming and Leisure (Pty) Ltd, TecMed (Pty) Ltd, Racing South Africa (Pty) Ltd, the Grayson-Jockey Club Research Foundation, the Racing Medication and Testing Consortium, the Thoroughbred Racing Trust of South Africa, and private donors.

The authors thank Graeme Hawkins, Elvarde van Zyl, Eddie Smith, Rob de Kock, Dr. Duncan MacDonnald, Dr. Dale Wheeler, Dr. Cindy Harper, Dr. Melvyn Quan, Dr. John Grewar, Dr. Patrick Page, Dr. Rosie Gerber, Dr. Cynthia Donnellan, Dr. Robin Moore, Dr. Karin Kruger, Stellest de Villiers, Anette Nel, Ilse Vorster, Roehan Sutherland, Taelo Sibi, Dr. Rick Sams, and Dr. Schalk de Kock for technical, logistic, and administrative assistance.

Address correspondence to Dr. Hinchcliff.
Cover Journal of the American Veterinary Medical Association
Journal of the American Veterinary Medical Association
Publication Date:
01 Jul 2009
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