Sex variation in the prevalence of exercise-induced pulmonary haemorrhage in racing quarter horses.

This study investigates the prevalence of exercise-induced pulmonary haemorrhage (EIPH) in two-year-old quarter horses and finds a significant variation based on the sex of the horses, with a notably lower prevalence in stallions compared to mares and geldings.

Research Methodology

• The researchers conducted a post-race endoscopy on a sample of 255 two-year-old quarter horses.
• The examination focused on identifying cases of exercise-induced pulmonary haemorrhage (EIPH), a condition characterized by bleeding from the lungs following intense exercise.
• The sample contained horses from both sexes: mares (females), geldings (castrated males), and stallions (intact males).

Key Findings

• EIPH was diagnosed in 166 of the horses, which equates to a prevalence rate of 65 percent within the sample.
• The prevalence of EIPH varied considerably between the sexes. The condition was found in 73 percent of mares and 74 percent of geldings.
• Stallions displayed a significantly lower prevalence of EIPH, with the condition diagnosed in just 49 percent of stallions – a difference that was statistically significant (P less than 0.01).
• The incidence of visible epistaxis (nosebleeds), a symptom of EIPH, was observed more frequently in geldings compared to either mares or stallions.

Conclusions

• The results of the study suggest a notable sex variation in the prevalence of EIPH among two-year-old quarter horses.
• Significantly lower rates in stallions indicate a possible physiological difference between the sexes that may influence the development of EIPH.
• This study could help inform further research into the causes of EIPH and potential sex-based treatment strategies.