Storage alters feline bronchoalveolar lavage fluid cytological analysis

Bronchoalveolar lavage fluid (BALF) collection is a valuable respiratory diagnostic procedure in cats. This study evaluated effects of BALF storage on total nucleated cell counts (TNCCs) and differential cell counts (DCC), cell morphology, and cytological diagnosis. Forty-five research cats with neutrophilic, eosinophilic, and mixed inflammation, and healthy controls were enrolled. BALF samples were processed within 1 h (baseline) or stored at 4°C (4C24) or room temperature (RT24) for 24 h, or 4°C (4C48) or room temperature (RT48) for 48 h before processing. Stored BALF at RT48 had decreased TNCC compared to baseline. The RT24 and RT48 samples had greater eosinophil % and the RT24, 4C48, and RT48 samples had decreased neutrophil % compared with baseline. Cellular morphology deteriorated in all stored samples. Storage resulted in a change in cytological diagnosis in up to 57% of stored samples. We conclude that cytological analysis of BALF in cats should be performed promptly for optimal results.