Exercise-induced pulmonary haemorrhage impairs racing performance in Thoroughbred racehorses.
Authors: Morley P S, Bromberek J L, Saulez M N, Hinchcliff K W, Guthrie A J
Journal: Equine veterinary journal
Summary
# Editorial Summary Exercise-induced pulmonary haemorrhage (EIPH) represents one of the most prevalent performance-limiting conditions in racing Thoroughbreds, yet robust evidence linking bleeding severity to actual race outcomes has been scarce until now. Researchers examined 1,000 South African racehorses using tracheobronchoscopic evaluation within two hours of racing, with three blinded observers independently grading EIPH severity from video recordings, whilst controlling for confounding variables such as horse age, sex and race distance. The findings were striking: 68% of horses exhibited some degree of EIPH, and those with no detectable bleeding (grade 0) were more than twice as likely to win races compared to affected horses, finished approximately one length ahead on average, and were 2.5 times more likely to achieve earnings in the top decile—establishing a clear performance hierarchy directly correlated with bleeding status. For practitioners managing elite racing stock, these results provide compelling evidence that EIPH assessment should feature prominently in pre-purchase evaluations and training monitoring protocols, particularly in horses not receiving furosemide prophylaxis or nasal dilator strips, as the performance disadvantage is both substantial and economically significant. Understanding that absence of EIPH confers a genuine competitive advantage reinforces the clinical importance of investigating and managing underlying causes—whether exercise intensity, airway obstruction, or susceptibility factors—rather than dismissing subclinical bleeding as merely incidental.
Read the full abstract on PubMed
Practical Takeaways
- •EIPH is highly prevalent in racing Thoroughbreds and significantly impairs competitive performance and earnings potential, making detection and management critical for racing operations
- •Tracheobronchoscopic examination within 2 hours of racing can identify EIPH and help predict performance outcomes in individual horses
- •For horses not treated with furosemide or nasal dilator strips, presence of EIPH is a major limiting factor for elite athletic performance and should inform training, medication, and racing decisions
Key Findings
- •68% of Thoroughbred racehorses had evidence of EIPH (grade ≥1)
- •Horses without EIPH were >2 times more likely to win races (OR=2.3, 95% CI 1.4-3.7, P=0.001)
- •Horses without EIPH finished an average of one length ahead of horses with EIPH (P=0.03)
- •Horses without EIPH were 2.5 times more likely to be in the highest decile in race earnings (OR=2.5, 95% CI 1.5-4.1, P<0.001)