EFFECT OF PRIOR LAVAGE ON BRONCHOALVEOLAR LAVAGE FLUID CELL-POPULATION OF LAVAGED AND UNLAVAGED LUNG SEGMENTS IN HORSES

Bronchoalveolar lavage (BAL) was performed on 16 horses to determine w hether it caused local or diffuse inflammation in the lungs. In 7 hors es, BAL was performed in both lungs twice, 48 hours apart. Although to tal cell. counts of the BAL samples did not change significantly, ther e were increased numbers and percentage of neutrophils in the second l avage fluid samples. In 5 horses, BAL was performed in 1 lung and repe ated 48 hours later in the same lung and in the corresponding airway i n the contralateral lung. The absolute cell count and percentage of ne utrophils were significantly (P = < 0.05) increased in the second samp le from the lung that was lavaged twice. In 4 horses, BAL was performe d in 1 lung and 48 hours later, repeated in an adjacent airway to the first BAL site, and in the corresponding airway in the contralateral l ung. Significant differences were not detected in the total or differe ntial cell counts of the BAL fluid recovered at any time, except for a n increase in neutrophil percentage in the second sample in the contra lateral lung. The increased neutrophil percentage values were within t he range of normal for healthy horses. Results of the study suggested that, in horses, BAL induces a localized pulmonary neutrophil influx t hat persists at least 48 hours and is characterized by a relative and absolute increase in the number of neutrophils in the lavage fluids.