Frequency of and risk factors for epistaxis associated with exercise-induced pulmonary hemorrhage in horses: 251,609 race starts (1992-1997).

The study investigates the occurrence of nose bleeds (or epistaxis) linked with exercise-induced pulmonary hemorrhage in racehorses, citing factors such as the type of race, horse’s age and sex, and distance covered in races. The shorter duration, high-intensity races seem to increase chances of such bleeding.

Study Overview

The research paper is a retrospective study that analyzes Thoroughbred and Anglo-Arab horse race starts sanctioned by the Japan Racing Association from 1992 to 1997. The primary focus of the study was to:

• Determine the frequency of epistaxis related to exercise-induced pulmonary hemorrhage (EIPH) occurring during or after racing among these racehorses
• Identify the risk factors associated with the development of such epistaxis

Every horse that participated in these races was examined by a veterinarian within 30 minutes of the race’s conclusion—endoscopic examinations were performed on horses that showed blood at their nostrils. The presence of blood in the trachea indicated EIPH-related epistaxis.

Findings and Conclusions

The research found that:

• Epistaxis related to EIPH followed 369 race starts, which equates to 0.15% of all starts.
• Various factors significantly impacted the frequency of EIPH-related epistaxis, specifically the type of race, the age of the horse, the distance of the race, and the sex of the horse.
• Nosebleeds were more common in steeplechase races compared to flat races and in older horses in comparison to two-year-old ones.
• Shorter races of less than or equal to 1,600m witnessed more incidences of nosebleeds in comparison to races ranging from 1,601m to 2,000m.
• Female horses displayed a higher likelihood of epistaxis than the sexually intact male horses.

The research concludes that the frequency of EIPH-related epistaxis among racehorses is significantly associated with the horse’s age and gender, the specific type of race, and the distance raced. More specifically, the study suggests a higher frequency of EIPH in shorter, more intense races, possibly indicating that they increase the chances of EIPH.