title: Association of tracheal mucus or blood and airway neutrophilia with racing performance in Thoroughbred horses in an Australian racing yard.
abstract: OBJECTIVE
  To determine the variation of tracheal mucus scores, tracheal blood scores and transendoscopic tracheal wash (TW) cytology in a population of Thoroughbred (TB) racehorses and assess their association with racing performance.
  
  
  METHODS
  A total of 220 endoscopic examinations were performed and TWs obtained from 155 TB racehorses. Samples were collected 60-120 min following gallop work. Tracheal mucus score, tracheal blood score and TW cytology were analysed and their association with racing performance assessed.
  
  
  RESULTS
  Of the total examinations and samples, 194 from 135 horses fitted the criteria for inclusion. The overall prevalence of visible tracheal mucus was 2.5% (5/194) and of increased tracheal mucus was 0%. The prevalence of visible tracheal blood was 8.8% (17/194) and of increased tracheal blood was 4.6% (9/194). A total of 36% (70/194) of TWs contained elevated percentages of neutrophils and of these, 96% (67/70) occurred in the absence of any visible tracheal mucus. There was no significant association between tracheal mucus score or TW cytology and subsequent racing performance. There was a statistically significant association (P = 0.004) between increased tracheal blood scores and poor racing performance.
  
  
  CONCLUSIONS
  Visible tracheal blood seen after strenuous exercise in clinically normal TB racehorses was a risk factor for poor racing performance, but the presence of airway neutrophilia was not. No horses in this study were found to have increased tracheal mucus, so the association of increased tracheal mucus with racing performance could not be assessed.
authors.affiliation: Randwick Equine Centre, 3 Jane Street, Randwick, NSW, 2031, Australia. rsalz@randwickequine.com.au.
authors.forename: R O
authors.initials: RO
authors.lastname: Salz
authors.affiliation: Randwick Equine Centre, 3 Jane Street, Randwick, NSW, 2031, Australia.
authors.forename: B J
authors.initials: BJ
authors.lastname: Ahern
authors.affiliation: Randwick Equine Centre, 3 Jane Street, Randwick, NSW, 2031, Australia.
authors.forename: R
authors.initials: R
authors.lastname: Boston
authors.affiliation: Randwick Equine Centre, 3 Jane Street, Randwick, NSW, 2031, Australia.
authors.forename: L M
authors.initials: LM
authors.lastname: Begg
mesh_terms: D000818:Animals; D001769:Blood / Q000378:metabolism; D001992:Bronchoalveolar Lavage Fluid / Q000737:chemistry / Q000166:cytology; D001999:Bronchoscopy / Q000662:veterinary; D006470:Hemorrhage / Q000097:blood / Q000503:physiopathology / Q000662:veterinary; D006734:Horse Diseases / Q000175:diagnosis / Q000473:pathology / Q000503:physiopathology; D006736:Horses / Q000502:physiology*; D007249:Inflammation / Q000175:diagnosis / Q000503:physiopathology / Q000662:veterinary; D016015:Logistic Models; D009093:Mucus / Q000737:chemistry*; D009305:Nasopharynx / Q000473:pathology; D009504:Neutrophils / Q000166:cytology*; D012140:Respiratory Tract Diseases / Q000175:diagnosis / Q000503:physiopathology / Q000662:veterinary; D012307:Risk Factors; D012420:Running / Q000293:injuries / Q000502:physiology; D014132:Trachea / Q000737:chemistry* / Q000166:cytology*
keywords: airways; endoscopy; horses; inflammation; racing performance; tracheal wash