Cytology of tracheobronchial aspirates in horses. Vet Pathol

Abstruct. Tracheobronchial aspirates were obtained from 27 normal horses and from 57 horses with respiratory disease. Aspirates from normal horses contained mainly ciliated columnar epithelial cells, mononuclear cells, a few neutrophils and mucus. Aspirates from horses with acute suppurative bronchopneumonias or chronic bronchiolitis had predomi-nantly neutrophils and usually large amounts of mucus; in severe suppurative inflammatory diseases, many of the cells were degenerated, and there were coils of fibrinous material resembling Curschmann’s spirals. Eosinophils were rarely found, even from horses with histories suggestive of allergic respiratory disease. Aspirates from horses with epistaxis frequently had macrophages with intracytoplasmic green globules (hemosiderin). Tracheo-bronchial aspirates occasionally revealed subclinical lung disease. Four horses with no clinical signs of lung disease and lungs that were unremarkable on percussion and normal on auscultation had aspirates suggestive of inflammation; histologic examination con-firmed bronchiolitis. Tracheobronchial aspirates are frequently used in diagnosis of pulmonary disease, especially neoplasia in man. Unlike man the horse rarely develops neoplasms of the respiratory tract, but aspirates are useful for understand-ing the type of reaction occurring in the airways and lung; they can also reveal subclinical pulmonary disease. The cell types in aspirates from normal horses and from those with certain respiratory diseases are described and their significance discussed. Materials and Methods Tracheobronchial aspirates were obtained from 27 horses free from respiratory disease; one sample was taken from an anesthetized horse, seven from horses immediately after death, and 19 from horses immediately before they were killed. Horses were regarded a