Prevalence and severity of exercise-induced pulmonary hemorrhage in 2-year-old Thoroughbred racehorses and its relationship to performance.
Authors: Shoemaker Sierra, Wang Yuan, Sellon Debra, Gold Jenifer, Fisher Allison, Bagshaw Julia, Leguillette Renaud, Sanz Macarena, Bayly Warwick
Journal: Journal of veterinary internal medicine
Summary
# Exercise-Induced Pulmonary Haemorrhage in Young Racehorses: Prevalence, Performance Impact and Furosemide Efficacy Exercise-induced pulmonary haemorrhage (EIPH) affects a substantial proportion of racing Thoroughbreds, yet limited data exist regarding its prevalence and clinical significance in the youngest cohort of racehorses. Researchers prospectively examined 830 two-year-old Thoroughbreds across 15 American racetracks, performing blinded videoendoscopic evaluation of the trachea within 30–60 minutes post-race to grade EIPH severity on a standardised 0–4 scale across 1,071 race entries. Three-quarters of young racehorses exhibited evidence of EIPH, though only 8% displayed severe haemorrhage (grade ≥3); importantly, severe EIPH correlated with measurably reduced speed index and worse finishing positions, suggesting a genuine performance penalty rather than an incidental finding. Prerace furosemide administration significantly reduced both the likelihood of EIPH occurring and its severity at voluntary-participation tracks, though notably, EIPH prevalence and severity were substantially lower at two facilities where endoscopic evaluation was mandatory rather than voluntary—a finding indicating potential selection bias in voluntary surveillance protocols. For practitioners managing young racing stock, these findings underscore that whilst low-grade EIPH appears nearly universal in this population and likely reflects normal physiological stress responses, severe haemorrhage warrants investigation as a potential performance-limiting condition, and that furosemide use may confer protective benefits, particularly at tracks without standardised post-race screening.
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Practical Takeaways
- •Severe EIPH (grade ≥3) negatively impacts race performance in young Thoroughbreds; routine postrace endoscopic screening helps identify affected horses
- •Furosemide administration before racing reduces the likelihood of EIPH occurrence, suggesting its use may be beneficial for horses at risk
- •Track management policies influence reported EIPH rates; mandatory screening protocols may identify cases that voluntary protocols miss, emphasizing importance of consistent monitoring protocols
Key Findings
- •EIPH prevalence was 74% in 2-year-old Thoroughbred racehorses, with severe EIPH (grade ≥3) occurring in 8% of cases
- •Severe EIPH (grade ≥3) was associated with lower speed index and worse finishing place performance
- •Prerace furosemide administration decreased the probability of EIPH occurrence by reducing likelihood but not severity
- •EIPH prevalence and severity were significantly lower at tracks with mandatory versus voluntary postrace endoscopy protocols