title: Bronchomalacia in dogs with myxomatous mitral valve degeneration.
abstract: BACKGROUND
  Cough in the geriatric small breed dog with myxomatous mitral valve degeneration (MMVD), a large left atrium, and absence of heart failure often is attributed to compression of the left mainstem bronchus by the left atrium. Studies investigating this syndrome are lacking in dogs.
  
  
  OBJECTIVE
  Airway collapse is independent of left atrial enlargement.
  
  
  METHODS
  A total of 16 dogs presenting with chronic cough in the absence of congestive heart failure. Group 1 dogs (n = 10) had moderate-to-severe left atrial enlargement based on an echocardiographically calculated left atrial:aortic surface area [LA:Ao(a)] > 6. Group 2 dogs (n = 6) had no to mild left atrial enlargement [LA:Ao(a) ≤ 6].
  
  
  METHODS
  Dogs were prospectively evaluated. CBC, biochemistry, urinalysis, cervical and thoracic radiographs, fluoroscopy, echocardiography, and bronchoscopy were performed. Bronchoscopic abnormalities were compared between groups using Fisher's Exact Test. P < .05 was considered significant.
  
  
  RESULTS
  Fluoroscopy identified airway collapse in both groups. Bronchoscopic evidence of airway collapse >50% was observed in multiple bronchi with no difference between groups. All dogs had inflammation on airway cytology with respiratory infection in 1 dog in group 2. Left atrial size was interpreted radiographically as enlarged in 9 of 10 group 1 dog and in 2 of 6 group 2 dogs. VHS was above normal in both groups of dogs regardless of echocardiographic evidence of cardiomegaly.
  
  
  CONCLUSIONS
  Results failed to identify an association between left atrial enlargement and airway collapse in dogs with MMVD, but did suggest that airway inflammation is common in dogs with airway collapse.
authors.affiliation: Cardiology Service, William R. Pritchard Veterinary Medical Teaching Hospital, University of California Davis, School of Veterinary Medicine, Davis, California, USA.
authors.forename: M K
authors.initials: MK
authors.lastname: Singh
authors.forename: L R
authors.initials: LR
authors.lastname: Johnson
authors.forename: M D
authors.initials: MD
authors.lastname: Kittleson
authors.forename: R E
authors.initials: RE
authors.lastname: Pollard
mesh_terms: D000818:Animals; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology; D055091:Bronchomalacia / Q000150:complications / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000662:veterinary*; D001999:Bronchoscopy / Q000662:veterinary; D003371:Cough / Q000503:physiopathology / Q000662:veterinary; D004283:Dog Diseases / Q000000981:diagnostic imaging / Q000503:physiopathology*; D004285:Dogs; D004452:Echocardiography / Q000662:veterinary; D008297:Male; D008944:Mitral Valve Insufficiency / Q000150:complications / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000662:veterinary*; D011859:Radiography