Prospective study of the association between exercise-induced pulmonary haemorrhage and long-term performance in Thoroughbred racehorses.

This research paper studies the impact of Exercise-induced pulmonary haemorrhage (EIPH) on the long-term performance of Thoroughbred racehorses; it concludes that the occurrence of severe EIPH may adversely affect the horse’s potential or ability to race.

Research Purpose and Objective

• The purpose of this research was to delve into the effects of Exercise-Induced Pulmonary Haemorrhage (EIPH) on Thoroughbred racehorses’ long-term performance.
• The aim was to determine the link between an instance of EIPH and a horse’s long-term athletic performance.
• Understanding the impact of EIPH on long-term performance would aid in devising management and treatment protocols for this disorder in racehorses.

Methods and Study Design

• The study was conducted prospectively from 2003 to 2012.
• A total of 744 Thoroughbred racehorses had a single tracheobronchoscopic examination in 2003 to detect the presence and severity of EIPH.
• After horses retired from their racing careers, their lifetime performance data (like career duration, earnings, races, victories, and placings) were extracted from a commercial database.
• Analyses were performed using survival analysis, linear regression and negative binomial regression to study the relationship between EIPH and various individual performance variables.

Findings and Results

• There was no detected association between a horse having any level of EIPH (grade ≥1) and any long-term performance measures, except for horses with EIPH grade ≥2 which earned less after the endoscopic examination compared to horses with mild EIPH or no EIPH (grades ≤1).
• Several links were found between severe EIPH (grade 4) and long-term performance measures, indicating that this grade of EIPH, usually associated with nosebleeds, negatively affects a horse’s chances of racing, or its physiological capacity to race.

Conclusions

• The study concludes that there is no link between EIPH grades 0, 1, 2, and 3 and the long-term racing performance of Thoroughbred racehorses.
• The only detected association was with severe (grade 4) EIPH, which seems to impact negatively on long-term race performance.
• These findings are based on a single endoscopic evaluation of EIPH grade made during a horse’s career. More research is needed to understand the reasons for the impaired performance linked to severe EIPH.