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

Toshiyuki Takahashi DVM1, Atsushi Hiraga DVM, PhD2, Hajime Ohmura DVM3, Makoto Kai DVM, PhD4, and James H. Jones PhD, DVM5
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  • 1 Equine Research Institute of the Japan Racing Association, 321-4 Tokami-Cho, Utsunomiya, Tochigi 320-0856, Japan.
  • | 2 Equine Science Division, Hidaka Yearling Training Farm of the Japan Racing Association, 535-13 Aza- Nishicha, Urakawa-Cho, Urakawa-Gun, Hokkaido 057-0171, Japan.
  • | 3 Equine Science Division, Hidaka Yearling Training Farm of the Japan Racing Association, 535-13 Aza- Nishicha, Urakawa-Cho, Urakawa-Gun, Hokkaido 057-0171, Japan.
  • | 4 Equine Research Institute of the Japan Racing Association, 321-4 Tokami-Cho, Utsunomiya, Tochigi 320-0856, Japan.
  • | 5 Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA 95616-8742.

Abstract

Objective—To determine the frequency of epistaxis during or after racing among racehorses and identify factors associated with development of epistaxis.

Design—Retrospective study.

Sample Population—247,564 Thoroughbred and 4,045 Anglo-Arab race starts.

Procedure—Race start information (breed, age, sex, racing distance, and race type) was obtained for Thoroughbred and Anglo-Arab horses racing in Japan Racing Association-sanctioned races between 1992 and 1997. All horses that raced were examined by a veterinarian within 30 minutes of the conclusion of the race; any horse that had blood at the nostrils was examined with an endoscope. If blood was observed in the trachea, epistaxis related to exercise-induced pulmonary hemorrhage (EIPH) was diagnosed.

Results—Epistaxis related to EIPH was identified following 369 race starts (0.15%). Frequency of EIPHrelated epistaxis was significantly associated with race type, age, distance, and sex. Epistaxis was more common following steeplechase races than following flat races, in older horses than in horses that were 2 years old, following races ≤ 1,600 m long than following races between 1,601 and 2,000 m long, and in females than in sexually intact males. For horses that had an episode of epistaxis, the recurrence rate was 4.64%.

Conclusions and Clinical Relevance—Results suggested that frequency of EIPH-related epistaxis in racehorses is associated with the horse's age and sex, the type of race, and the distance raced. The higher frequency in shorter races suggests that higher intensity exercise of shorter duration may increase the probability of EIPH. (J Am Vet Med Assoc 2001;218:1462–1464)

Abstract

Objective—To determine the frequency of epistaxis during or after racing among racehorses and identify factors associated with development of epistaxis.

Design—Retrospective study.

Sample Population—247,564 Thoroughbred and 4,045 Anglo-Arab race starts.

Procedure—Race start information (breed, age, sex, racing distance, and race type) was obtained for Thoroughbred and Anglo-Arab horses racing in Japan Racing Association-sanctioned races between 1992 and 1997. All horses that raced were examined by a veterinarian within 30 minutes of the conclusion of the race; any horse that had blood at the nostrils was examined with an endoscope. If blood was observed in the trachea, epistaxis related to exercise-induced pulmonary hemorrhage (EIPH) was diagnosed.

Results—Epistaxis related to EIPH was identified following 369 race starts (0.15%). Frequency of EIPHrelated epistaxis was significantly associated with race type, age, distance, and sex. Epistaxis was more common following steeplechase races than following flat races, in older horses than in horses that were 2 years old, following races ≤ 1,600 m long than following races between 1,601 and 2,000 m long, and in females than in sexually intact males. For horses that had an episode of epistaxis, the recurrence rate was 4.64%.

Conclusions and Clinical Relevance—Results suggested that frequency of EIPH-related epistaxis in racehorses is associated with the horse's age and sex, the type of race, and the distance raced. The higher frequency in shorter races suggests that higher intensity exercise of shorter duration may increase the probability of EIPH. (J Am Vet Med Assoc 2001;218:1462–1464)