title: Relationships between equine airway reactivity measured by flowmetric plethysmography and specific indicators of airway inflammation in horses with suspected inflammatory airway disease.
abstract: BACKGROUND
  Agreement between airway reactivity measured by flowmetric plethysmography and histamine bronchoprovocation, and lower airway inflammation measured by bronchoalveolar lavage (BAL) cytology, has not been studied in horses with suspected inflammatory airway disease (IAD).
  
  
  OBJECTIVE
  We tested the hypothesis that airway reactivity is associated with BAL cytology in horses presenting for unexplained poor performance and/or chronic cough.
  
  
  METHODS
  Prospective clinical study.
  
  
  METHODS
  Forty-five horses, predominantly young Standardbred racehorses, presenting for unexplained poor performance or chronic cough, underwent endoscopic evaluation, tracheal wash, flowmetric plethysmography with histamine bronchoprovocation and BAL. Histamine response was measured by calculating PC35, the concentration of nebulised histamine eliciting an increase in Δflow of 35%.
  
  
  RESULTS
  In this population, there was no significant correlation between histamine response and cell populations in BAL cytology. When airway hyperreactivity (AHR) was defined as ≥35% increase in Δflow at a histamine concentration of <6 mg/ml, 24 of the 45 horses (53%) were determined to have AHR. Thirty-three (73%) had either abnormal BAL cytology or AHR, and were diagnosed with IAD on this basis. Of horses diagnosed with IAD, 9 (27%) had an abnormal BAL, 11 (33%) had AHR and 13 (39%) had both.
  
  
  CONCLUSIONS
  Airway reactivity and BAL cytology did not show concordance in this population of horses presenting for unexplained poor performance and/or chronic cough. Failure to include tests of airway reactivity may lead to underdiagnosis of IAD in young Standardbred racehorses that present with clinical signs suggestive of IAD.
authors.affiliation: Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, Prince Edward Island.
authors.forename: M
authors.initials: M
authors.lastname: Wichtel
authors.affiliation: Department of Pathobiology, Ontario Veterinary College, University of Guelph, Ontario, Canada.
authors.forename: D
authors.initials: D
authors.lastname: Gomez
authors.affiliation: Department of Veterinary Pathology and Microbiology, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, Prince Edward Island.
authors.forename: S
authors.initials: S
authors.lastname: Burton
authors.affiliation: Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, Prince Edward Island.
authors.forename: J
authors.initials: J
authors.lastname: Wichtel
authors.affiliation: Department of Clinical Sciences, Tufts University Cummings School of Veterinary Medicine, Boston, Massachusetts, USA.
authors.forename: A
authors.initials: A
authors.lastname: Hoffman
mesh_terms: D000818:Animals; D001986:Bronchial Spasm / Q000139:chemically induced / Q000175:diagnosis / Q000662:veterinary*; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology; D006632:Histamine / Q000009:adverse effects; D006734:Horse Diseases / Q000175:diagnosis* / Q000473:pathology; D006736:Horses; D007249:Inflammation / Q000175:diagnosis / Q000662:veterinary*; D008171:Lung Diseases / Q000175:diagnosis / Q000662:veterinary*; D010991:Plethysmography / Q000662:veterinary*; D011446:Prospective Studies
chemical_list: D006632:Histamine
keywords: bronchoalveolar lavage; diagnosis; flowmetric plethysmography; horse; inflammatory airway disease; pulmonary function testing