Extraesophageal reflux and reflux aspiration in dogs with respiratory diseases and in healthy dogs

BACKGROUND: Salivary bile acids are used to diagnose extraesophageal reflux (EER) and to evaluate the risk of reflux aspiration that is associated with respiratory diseases in dogs. OBJECTIVES: To study total bile acid (TBA) concentrations in saliva and in bronchoalveolar lavage fluid (BALF) to investigate EER and reflux aspiration in dogs with respiratory diseases and in healthy dogs. ANIMALS: Thirty‐one West Highland White Terriers (WHWTs) with idiopathic pulmonary fibrosis (IPF), 12 dogs with inflammatory airway disease (IAD), 6 dogs with recurrent pneumonia (RP), 26 brachycephalic dogs (BD), 27 healthy WHWTs (HW), 52 healthy dogs (HD). All privately‐owned dogs. METHODS: Saliva and BALF were collected from dogs in each group. RESULTS: Salivary TBA concentrations were higher in IPF (median 0.1692 μM, interquartile range [IQR] 0.1115‐0.2925 μM, Cohen's d 3.4, 95% confidence interval [CI] 2.2‐4.0, P < .001) and BD (0.0256 μM, IQR 0.0086‐0.0417 μM, d 0.5, CI −0.1 to 1.1, P = .003) compared to HD (0 μM, IQR not quantifiable [n.q.]‐0.0131 μM). Bronchoalveolar lavage fluid TBA concentrations were higher in IPF (0.0117 μM, IQR 0.0048‐0.0361 μM, d 0.5, CI 0‐1.1, P < .001) compared to HD (0 μM, IQR n.q.‐0.0074 μM). CONCLUSION AND CLINICAL IMPORTANCE: Extraesophageal reflux and reflux aspiration occur in healthy dogs and those with respiratory diseases.