Exercise-induced pulmonary haemorrhage in Thoroughbred racehorses: a longitudinal study.

This study explores the progression of exercise-induced pulmonary haemorrhage (EIPH) in Thoroughbred racehorses and identifies factors that can affect changes in the severity of the condition.

Research Aim and Methodology

• The primary aim of the research was to study the changes in tracheobronchoscopic EIPH over time in Thoroughbred racehorses. Additionally, the study sought to identify factors that affect changes in the severity of EIPH between observations.
• The study was conducted as a prospective, longitudinal, observational cross-sectional analysis.
• Horses were examined using tracheobronchoscopy at least 30 minutes after racing. This examination was graded on a 0-4 scale by experienced veterinarians who did not know the history of the horses.
• Only horses who had two or more observations were included in the analysis.
• In order to establish the correlation between previous and current EIPH scores, a linear mixed effect model was used.
• Multiple ordinal regression was applied to identify factors associated with transitioning from a lower to a high EIPH grade or vice versa.
• The number of career starts was used as a time marker in a semi-parametric regression model to study progression. The models were adjusted to accommodate potential confounding variables.

Research Results

• The research comprised 2974 tracheobronchoscopic examinations performed on 747 horses.
• Blood was detected in more than half of the examinations (55.6%), suggesting the presence of EIPH.
• The prevalence of EIPH in the population increased as the number of examinations for each horse increased.
• The previous EIPH score was significantly linked to the current EIPH score.
• Ambient temperature, the number of days since last racing, and weight carried by the horse were found to be significant variables that influenced the movement between EIPH grades.
• The progression of tracheobronchoscopic EIPH was mild over the first 30 career starts for the horse.

Conclusions and Recommendations

• The research had voluntary enrolment and horses were not followed for their entire career, which may impact its comprehensiveness.
• The study recommends limiting the race days and spacing races for horses with moderate to severe EIPH to help reduce the severity of tracheobronchoscopic EIPH.
• The study also suggests further investigation into the association between ambient temperature and EIPH as temperature was found to be a significant factor in the progression of the condition.