title: Analysis of risk factors for recurrent airway obstruction in North American horses: 1,444 cases (1990-1999).
abstract: OBJECTIVE
  To identify risk factors for recurrent airway obstruction (RAO) among horses examined at veterinary teaching hospitals in North America.
  
  
  METHODS
  Retrospective case-control study.
  
  
  METHODS
  1,444 horses with RAO and 1,444 control horses examined for other reasons.
  
  
  METHODS
  The Veterinary Medical Database was searched for records of horses in which RAO was diagnosed. A control group was identified by randomly selecting a horse with a diagnosis other than RAO that matched the institution and year of admission for each of the horses with RAO. Information obtained included hospital, admission year and month, age, sex, breed, and discharge status. The association between risk factors and diagnosis of RAO was estimated with logistic regression models.
  
  
  RESULTS
  The risk of RAO increased significantly with age, with horses > or = 7 years old being 6 to 7 times as likely to have RAO as were horses < or = 4 years old. Thoroughbreds were 3 times as likely to have RAO as were ponies. Horses were 1.6 and 1.5 times as likely to be examined because of RAO during winter and spring, respectively, than they were during summer.
  
  
  CONCLUSIONS
  Results suggest that RAO was more likely to be diagnosed in females, horses > or = 4 years old, and Thoroughbreds and that RAO has a seasonal distribution.
authors.affiliation: Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Purdue University, West Lafayette, IN 47907, USA.
authors.forename: Laurent L
authors.initials: LL
authors.lastname: Couëtil
authors.forename: Michael P
authors.initials: MP
authors.lastname: Ward
mesh_terms: D000367:Age Factors; D000402:Airway Obstruction / Q000453:epidemiology / Q000209:etiology / Q000662:veterinary*; D000818:Animals; D001947:Breeding; D016022:Case-Control Studies; D016001:Confidence Intervals; D005260:Female; D006734:Horse Diseases / Q000453:epidemiology* / Q000209:etiology*; D006736:Horses; D016015:Logistic Models; D008297:Male; D016017:Odds Ratio; D011996:Records / Q000662:veterinary; D012008:Recurrence; D012189:Retrospective Studies; D012307:Risk Factors; D012621:Seasons; D012737:Sex Factors; D014481:United States / Q000453:epidemiology