Tracheobronchial Brush Cytology and Bronchoalveolar Lavage in Dogs and Cats with Chronic Cough: 45 Cases (2012–2014)

BACKGROUND: Animals with chronic cough can have normal bronchoalveolar lavage fluid cytology when small airway disease is absent. Cytology of a tracheobronchial brushing can detect inflammation in larger airways; however, evaluation of this technique has been limited in veterinary medicine. OBJECTIVE: To compare airway brush cytology to bronchoalveolar lavage fluid analysis in dogs and cats with chronic cough. ANIMALS: Forty dogs and five cats undergoing bronchoscopic investigation of chronic cough. METHODS: Prospective study. Bronchoscopy and bronchoalveolar lavage were performed followed by tracheobronchial brushing of central airways. Results of cytologic assessment of BAL fluid and brush cytology were compared for the presence or absence of inflammation and concordance of inflammatory cell type. RESULTS: Brush cytology detected central airway inflammation in 34 of 40 (85%) dogs with inflammatory BAL fluid. However, the type of inflammation reported differed in 23 of 34 dogs. In five cats with inflammation in BAL fluid, brush cytology detected inflammation in four; the type of inflammation was discordant in all cats. CONCLUSIONS AND CLINICAL RELEVANCE: Brush cytology has good agreement with BAL regarding the presence of inflammation, although the type of inflammation detected with the different sampling techniques commonly varies. Brush cytology can provide supplementary information to BAL, and additional studies will provide further information on the role of tracheobronchial brush cytology in the diagnosis and management of respiratory conditions.