Prevalence and severity of exercise-induced pulmonary hemorrhage in 2-year-old Thoroughbred racehorses and its relationship to performance.

This research investigates the frequency and severity of exercise-induced pulmonary hemorrhage in young Thoroughbred racehorses, exploring its impacts on their performance and how factors like the use of furosemide, race distance, and track surface relate to it.

Research Objective and Methodology

• The study aims to explore the prevalence (how common it is) and severity (how bad it is) of exercise-induced pulmonary hemorrhage (EIPH) in 2-year-old Thoroughbred racehorses, and its impact on the horse’s performance.
• The researchers also want to understand the relationship between EIPH and other variables including performance, speed index, furosemide use, race distance, and track surface.
• To gather data, 830 two-year-old Thoroughbreds were studied through a prospective blinded observational study.
• Post-race videoendoscopy tests were performed on the horses at 15 American racetracks, allowing the researchers to assess the horses’ pulmonary state immediately after a race.
• Three independent observers separately assigned an EIPH grade (ranging from 0 to 4) to every horse, which was used to calculate the prevalence and severity of the condition.

Statistical Analysis

• Various statistical tests, such as Pearson’s chi-squared test and analysis of variance (ANOVA), were used to study how EIPH grades related to performance, speed index, race distance, track surface, and the administration of furosemide before races.
• A p-value less than 0.05 was considered to be significant statistically.
• Multiple logistic regression was used to investigate the relationship between EIPH prevalence and severity, among other variables.

Results of the Research

• A total of 1071 tracheoendoscopies (an examination of the windpipe) were recorded.
• Prevalence of EIPH was found to be high – reports indicated it was present in 74% of the horses, and the severity of grade ≥3 was found in 8% of the horses.
• There was a clear association between a higher EIPH grade (≥3) and lower performance, indicated by speed index and finishing placement.
• The occurrence and severity of EIPH was lower in those racing circuits where the post-race endoscopy was mandatory rather than voluntary.
• Administering furosemide before races decrease the occurrence and severity of EIPH, but only in racecourses where participation in the study was voluntary.

Conclusions Drawn from the Study

• The study concluded that the prevalence and severity of EIPH in two-year-old racehorses were in line with that of older racehorses.
• A higher EIPH grade was associated with decreased performance.
• Prerace administration of furosemide was associated with a reduced likelihood of EIPH, but not severity, at most tracks.