Cytological Findings in Bronchoalveolar Lavage Fluid of Foals With Pneumonia Caused by Rhodococcus equi and Other Bacteria.

The distinction between lower respiratory tract infections caused by Rhodococcus equi and those caused by other pathogens is difficult. The aim of this retrospective study was to describe cytological findings in bronchoalveolar lavage fluid (BALF) of foals with pneumonia caused by R. equi or other bacteria. Nineteen foals aged from 3 weeks to 6 months with evidence of respiratory disease between 2015 and 2016 were selected from the database of the Veterinary Teaching Hospital "Mario Modenato" of the University of Pisa. Eight foals of 19 (42.1%) had R. equi pneumonia, whereas 11 of 19 (57.9%) had another bacterial pneumonia. R. equi –positive foals had statistically significant higher total nucleated cell count (P =.02) and neutrophils percentage (P =.002) than R. equi –negative ones. Macrophages proportion (P =.01) was lower in R. equi –positive than in R. equi –negative foals. Bronchoalveolar lavage is a quite easy procedure that can be performed in the field with minimal equipment required. Here we reported significant differences in the cellular composition of BALF that can be used to differentiate foals with R. equi bronchopneumonia from those with other bacterial pneumonias, whereas waiting for culture results. • Differentiating between Rhodococcus equi and other bacterial pneumonia is difficult. • Bronchoalveolar lavage fluid (BALF) culture for R. equi pneumonia is time-consuming. • Cytology of BALF can identify foals with R. equi from other bacterial pneumonias. • Bronchoalveolar lavage fluid in foals with R. equi pneumonia can be used while waiting for culture result. [ABSTRACT FROM AUTHOR]