Descriptive analysis of longitudinal endoscopy for exercise-induced pulmonary haemorrhage in Thoroughbred racehorses training and racing at the Hong Kong Jockey Club.
Authors: Preston S A, Riggs C M, Singleton M D, Troedsson M H T
Journal: Equine veterinary journal
Summary
# Exercise-Induced Pulmonary Haemorrhage in Racehorses: A Hong Kong Longitudinal Study Over 800 Thoroughbred geldings imported to Hong Kong were tracked across multiple endoscopic examinations to establish the true prevalence and severity of exercise-induced pulmonary haemorrhage (EIPH) in the absence of furosemide prophylaxis—a significant gap in the literature, as most longitudinal EIPH data comes from medicated populations. Researchers retrospectively assigned horses to four categories based on endoscopic findings and clinical signs, with the majority (89%) undergoing at least one endoscopy (median 15 examinations per horse), revealing EIPH in 55% of examined animals at variable severity grades. Counter to conventional assumptions, horses with endoscopically confirmed EIPH showed no difference in racing participation rates or number of Hong Kong starts compared to unaffected horses, and notably had longer racing careers and extended time to retirement. The severity grade proved clinically informative: mild EIPH (grade <3) typically prompted retirement for unrelated reasons, whilst severe cases (grade ≥3) were specifically retired due to EIPH, though frank epistaxis occurred in only 4% of the cohort and most EIPH diagnoses (63%) followed racing rather than during routine training examinations. For equine professionals, these findings suggest that endoscopic EIPH detection alone should not automatically curtail a horse's racing career—management decisions warrant consideration of severity grade, clinical signs, and individual performance patterns rather than relying on haemorrhage presence as a categorical limitation.
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Practical Takeaways
- •EIPH is highly prevalent (55%) in racing Thoroughbreds but does not necessarily limit racing career length or number of starts in the absence of furosemide prophylaxis
- •Endoscopy is most effective for EIPH diagnosis after racing when clinical signs are most apparent; severity grading helps predict retirement outcome
- •Horses with mild EIPH can sustain productive racing careers and are typically retired for unrelated reasons, whereas severe EIPH becomes the limiting factor
Key Findings
- •55% of 822 Thoroughbred geldings were diagnosed with EIPH via endoscopy, with varying severity grades
- •EIPH was diagnosed most frequently (63%) after racing rather than during training
- •No significant difference in racing career longevity or number of starts between EIPH+ and EIPH- horses trained without furosemide
- •Mild EIPH (grade <3) horses were retired for other causes, while severe EIPH (grade ≥3) horses were more likely retired due to the condition itself