Bronchoalveolar lavage fluid (BALF) collection is an important diagnostic tool for cats with respiratory disease, especially lower respiratory tract disease. The accurate cytological evaluation of BALF is a useful means of differentiating disease processes. The procedure can also be used as a means to monitor the progression of disease or the response to therapy. The effects of storage on BALF values of total nucleated cell counts (TNCC) and differential cell counts (DCC), cell morphology and cytological diagnosis were evaluated. Samples from 45 research cats with neutrophilic, eosinophilic, and mixed inflammation and healthy controls were utilized for the study. The BALF samples were evaluated at 1 hour, or stored at 4 C° or room temperature for 24 hours, or 4 C° or room temperature for 48 hours. Storage of feline BALF at various time and temperature conditions alters TNCC and DCC, cellular morphology, and cytological diagnosis. There was a significant decrease in BALF TNCC in samples stored at room temperature for 48 hours. There was also an increase in the percentage of BALF eosinophils following storage at room temperature for 24 and 48 hours. The authors noted that it is important to remember that the relative increase in percentage of eosinophils is the result in a decrease in other cell lines due to cellular apoptosis accelerated with the storage at room temperature. Following storage, there was a misclassification of the cytological analysis of BALF from inflammatory airway disease to non-inflammatory in 9-18% of the samples. Many BALF samples (31-57%) had a change in cytological diagnosis following storage, similarly rising along with the increase in storage time and temperature. Ideally, analysis of feline BALF should be performed promptly after collection. [VT]
Nafe L, Declue AE, Lee-Fowler TM, et al. Evaluation of biomarkers in bronchoalveolar lavage fluid for discrimination between asthma and chronic bronchitis in cats. Am J Vet Res 2010;71:583-591.