The association between exercise-induced pulmonary haemorrhage and race-day performance in Thoroughbred racehorses.
Authors: Crispe E J, Lester G D, Secombe C J, Perera D I
Journal: Equine veterinary journal
Summary
# Exercise-Induced Pulmonary Haemorrhage and Racehorse Performance Exercise-induced pulmonary haemorrhage (EIPH) is frequently blamed for poor racing outcomes, yet evidence supporting this relationship remains sparse and contradictory. Researchers examined 3,794 racing observations from 1,567 Thoroughbreds between 2012 and 2015, grading endoscopic evidence of EIPH (0–4 scale) within 30 minutes of competition and correlating findings with multiple performance metrics including finishing position, earnings, and final-600 m velocity. Only severe haemorrhage (grade 4) demonstrated meaningful associations with inferior performance—affected horses were significantly less likely to place in the first three, earned less per start, and slowed markedly over the closing stages compared to grade-0 horses, with similar patterns evident when comparing grades ≥3 to ≤2. Crucially, mild to moderate EIPH (grades 1–2) showed no association with diminished race-day performance, suggesting that not all endoscopic findings warrant clinical concern or intervention. For practitioners, these findings imply that whilst severe pulmonary haemorrhage warrants investigation and management, mild cases observed during routine screening may represent physiological adaptation rather than performance-limiting pathology, allowing more targeted and evidence-based decision-making around training modifications and therapeutic intervention.
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Practical Takeaways
- •Only severe EIPH (grades 3-4) appears to meaningfully impact race performance; mild to moderate haemorrhage detected post-race does not necessarily predict poor results
- •Endoscopic grading of EIPH severity is clinically relevant for identifying horses with grade 4 disease that warrant investigation and management for performance issues
- •Racing veterinarians should focus intervention efforts on horses with severe EIPH rather than treating all detected haemorrhage as performance-limiting
Key Findings
- •EIPH was detected in 55.1% of 3794 observations from racing Thoroughbreds
- •Grade 4 EIPH was significantly associated with lower finishing positions, reduced earnings, and slower performance over the final 600m compared to grade 0
- •EIPH grades ≥3 showed inferior performance compared to grades ≤2 in multivariable analysis
- •Mild to moderate EIPH (grades 1-2) was not associated with inferior race-day performance