Reflux aspiration in lungs of dogs with respiratory disease and in healthy West Highland White Terriers

Background: Gastroesophageal reflux and microaspiration (MA) of gastric juice are associated with various human respiratory diseases but not in dogs. Objective: To detect the presence of bile acids in bronchoalveolar lavage fluid (BALF) of dogs with various respiratory diseases. Animals: Twenty-seven West Highland White Terriers (WHWTs) with canine idiopathic pulmonary fibrosis (CIPF), 11 dogs with bacterial pneumonia (BP), 13 with chronic bronchitis (CB), 9 with eosinophilic bronchopneumopathy (EBP), 19 with laryngeal dysfunction (LD), 8 Irish Wolfhounds (IWHs) with previous BPs, 13 healthy WHWTs, all privately owned dogs, and 6 healthy research colony Beagles. Methods: Prospective cross-sectional observational study with convenience sampling of dogs. Bile acids were measured by mass spectrometry in BALF samples. Total bile acid (TBA) concentration was calculated as a sum of 17 different bile acids. Results: Concentrations of TBA were above the limit of quantification in 78% of CIPF, 45% of BP, 62% of CB, 44% of EBP, 68% of LD, and 13% of IWH dogs. In healthy dogs, bile acids were detected less commonly in Beagles (0/6) than in healthy WHWTs (10/13). Concentrations of TBA were significantly higher in CIPF (median 0.013 μM, range not quantifiable [n.q.]-0.14 μM, P <.001), healthy WHWTs (0.0052 μM, n.q.-1.2 μM, P =.003), LD (0.010 μM, n.q.-2.3 μM, P =.015), and CB (0.0078 μM, n.q.-0.073 μM, P =.018) groups compared to Beagles (0 μM, n.q.). Conclusion and Clinical Importance: These results suggest that MA occurs in various respiratory diseases of dogs and also in healthy WHWTs.