title: Prospective study of the association between exercise-induced pulmonary haemorrhage and long-term performance in Thoroughbred racehorses.
abstract: BACKGROUND
  Exercise-induced pulmonary haemorrhage (EIPH) is associated with impaired short-term race performance but consequences to long-term race performance of Thoroughbred racehorses are unknown. Knowledge of effects of EIPH on performance over a prolonged time would inform the need for management and treatment of this disorder.
  
  
  OBJECTIVE
  To determine the relationship between EIPH detected on a single occasion and long-term athletic performance in Thoroughbred racehorses.
  
  
  METHODS
  Prospective, longitudinal, observational epidemiological study conducted from 2003 to 2012.
  
  
  METHODS
  Seven hundred and forty-four Thoroughbred racehorses underwent a single tracheobronchoscopic examination to determine presence and severity of EIPH in 2003. Following retirement of all the horses from racing, career after examination and lifetime performance data (including career duration, earnings, starts, wins and placings) were abstracted from a commercial database. The association between presence and severity of EIPH and individual performance variables were analysed using survival analysis, linear regression and negative binomial regression.
  
  
  RESULTS
  No association was detected between the presence of any EIPH (grade ≥1) and all measures of long-term performance examined except that horses with EIPH (grade ≥2) had fewer earnings after endoscopic examination than did horses with mild EIPH or no EIPH (grades ≤1). Multiple associations were detected between the most severe form of EIPH (grade 4) and measures of long-term performance suggesting that the severity of EIPH commonly associated with epistaxis adversely affects either the horse's opportunity to race or physiologic capacity to race.
  
  
  CONCLUSIONS
  We conclude that there is no association between EIPH grades 0, 1, 2 and 3 and long-term racing performance of Thoroughbred racehorses. These results are based on a single endoscopic evaluation of EIPH grade made during a horse's career. Further studies are required to determine the reasons for an association of severe (grade 4) EIPH with impaired long-term race performance.
authors.affiliation: Faculty of Veterinary Science, University of Melbourne, Werribee, Victoria, Australia.
authors.forename: S L
authors.initials: SL
authors.lastname: Sullivan
authors.forename: G A
authors.initials: GA
authors.lastname: Anderson
authors.forename: P S
authors.initials: PS
authors.lastname: Morley
authors.forename: K W
authors.initials: KW
authors.lastname: Hinchcliff
mesh_terms: D000818:Animals; D005500:Follow-Up Studies; D006470:Hemorrhage / Q000209:etiology / Q000662:veterinary*; D006734:Horse Diseases / Q000473:pathology*; D006736:Horses; D008171:Lung Diseases / Q000209:etiology / Q000662:veterinary*; D010805:Physical Conditioning, Animal / Q000009:adverse effects*; D005082:Physical Exertion; D011446:Prospective Studies; D012420:Running; D013177:Sports
keywords: exercise; horse; racing performance; survival analysis