A systematic review and meta-analysis of the efficacy of furosemide for exercise-induced pulmonary haemorrhage in Thoroughbred and Standardbred racehorses.
Authors: Sullivan S L, Whittem T, Morley P S, Hinchcliff K W
Journal: Equine veterinary journal
Summary
# Editorial Summary: Furosemide Efficacy for Exercise-Induced Pulmonary Haemorrhage Despite furosemide being the standard preventive treatment for exercise-induced pulmonary haemorrhage (EIPH) in racing Thoroughbreds and Standardbreds, the strength of evidence supporting its use had never been rigorously synthesised. Sullivan and colleagues conducted a systematic review and meta-analysis of 17 studies (ranging from observational to randomised controlled trials) to quantify furosemide's effect on EIPH detection rates and severity as measured by tracheobronchoscopy or bronchoalveolar lavage. Across all studies, furosemide reduced the relative risk of detecting EIPH by 12% (relative risk 0.88), but when analysing only the two high-quality randomised controlled trials involving 405 horses, the protective effect was substantially stronger at 32% risk reduction (relative risk 0.68); additionally, 68% of horses previously diagnosed with EIPH showed at least one-grade improvement in severity after treatment. These findings indicate that whilst furosemide demonstrably reduces both EIPH incidence and severity, the evidence base remains limited to a small number of rigorously controlled studies, underlining the need for further robust clinical trials. For practitioners, the results support continued use of furosemide as a preventive strategy in horses with a history of EIPH, though the modest effect size warrants consideration of complementary management strategies such as optimising training load, environmental conditions, and airway health.
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Practical Takeaways
- •Furosemide demonstrably reduces both the detection and severity of EIPH in racehorses, with approximately two-thirds of previously affected horses showing improvement of at least one grade
- •Evidence quality is higher in randomized controlled trials than observational studies, suggesting furosemide is a justified first-line treatment for EIPH management
- •While furosemide is effective, the 12% residual risk of EIPH detection even with treatment suggests it should be combined with other management strategies rather than used as monotherapy
Key Findings
- •Furosemide reduced the relative risk of detecting EIPH by tracheobronchoscopy to 0.88 across 11 studies (95% CI 0.79-0.97, P=0.01)
- •High-quality RCTs showed stronger effect with relative risk of 0.68 for endoscopically evident EIPH (95% CI 0.58-0.79, P<0.001)
- •68% of horses previously diagnosed with EIPH experienced reduction by at least one grade after furosemide administration (95% CI 61-78%)
- •High-quality evidence, though limited in quantity, supports furosemide efficacy for reducing EIPH incidence and severity in Thoroughbred and Standardbred racehorses