title: Exercise-induced pulmonary haemorrhage impairs racing performance in Thoroughbred racehorses.
abstract: BACKGROUND
  Exercise-induced pulmonary haemorrhage (EIPH) occurs commonly in Thoroughbred racehorses worldwide. While EIPH is believed to be an important cause of impaired performance in these horses, there is limited evidence from sufficiently powered studies to evaluate this association.
  
  
  OBJECTIVE
  To evaluate whether EIPH is associated with finishing position, distance finished behind race winners and differences in race earning among Thoroughbred horses racing in South Africa.
  
  
  METHODS
  Prospective cross-sectional study.
  
  
  METHODS
  One thousand Thoroughbred horses racing in South Africa were enrolled prior to a single race and underwent tracheobronchoscopic examination within 2 h of racing. Three observers, blinded to the horses' identity and race performance, independently evaluated EIPH occurrence and severity using video recordings of the examination. Data were analysed using multivariable logistic and linear regression while controlling for important horse and race factors as potential confounding variables.
  
  
  RESULTS
  Overall, 68% of horses had evidence of EIPH (grade ≥1). Horses without evidence of EIPH (severity grade 0), when compared with horses with any evidence of EIPH (grade ≥1), were >2 times more likely to win races (odds ratio = 2.3; 95% confidence interval 1.4-3.7; P = 0.001), finished an average of one length ahead of horses with EIPH (P = 0.03), and were 2.5 times more likely to be in the highest decile in race earnings (odds ratio = 2.5, 95% CI 1.5-4.1, P<0.001). However, no association was identified regarding finishing in the top 3 positions or earning money when analysed as a continuous variable or analysed as any winnings vs. none.
  
  
  CONCLUSIONS
  Exercise-induced pulmonary haemorrhage was associated with impaired performance in Thoroughbred racehorses not medicated with furosemide and not using nasal dilator strips. These findings provide strong corroboration of previous research indicating that the occurrence of EIPH has a major impact on the ability of Thoroughbred racehorses to compete successfully as elite athletes.
authors.affiliation: Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, USA.
authors.forename: P S
authors.initials: PS
authors.lastname: Morley
authors.forename: J L
authors.initials: JL
authors.lastname: Bromberek
authors.forename: M N
authors.initials: MN
authors.lastname: Saulez
authors.forename: K W
authors.initials: KW
authors.lastname: Hinchcliff
authors.forename: A J
authors.initials: AJ
authors.lastname: Guthrie
mesh_terms: D000818:Animals; D003430:Cross-Sectional Studies; D005260:Female; D006470:Hemorrhage / Q000209:etiology / Q000662:veterinary*; D006734:Horse Diseases / Q000473:pathology*; D006736:Horses; D008171:Lung Diseases / Q000209:etiology / Q000662:veterinary*; D008297:Male; D010805:Physical Conditioning, Animal / Q000009:adverse effects*; D005082:Physical Exertion; D011446:Prospective Studies; D012420:Running; D013019:South Africa; D013177:Sports
keywords: eiph; exercise; haemorrhage; horse; lung; risk factor