Tracheitis in pigs
Josepha DeLay, Murray Hazlett
In recent months, we have diagnosed tracheitis more frequently in swine cases submitted to the AHL (Figs. 1-3). Influenza A virus and possibly other undetermined viruses may contribute to tracheitis, although bacterial tracheitis predominates in most cases. This may reflect secondary bacterial infection and the subacute-to-chronic stage of the disease process. Trachea is infrequently included among samples received for microbiologic testing and histopathology. Please remember to include both fresh / frozen and formalin-fixed trachea among samples submitted for respiratory disease cases. AHL
Figure 1. Mild tracheitis. Tracheal mucosal epithelium is intact and mildly hyperplastic (bracket). Neutrophils are migrating through epithelium; lymphocytes and neutrophils in underlying lamina propria-submucosa.
Figure 2. Erosive tracheitis. The mucosal epithelial layer is very thin and epithelial cells are attenuated (arrow). Lymphocytes expand lamina propria-submucosa.
Figure 3. Severe ulcerative tracheitis. Mucosal epithelium replaced by fibrin, degenerate neutrophils, and bacteria (arrow). Edema, fibrin, and hemorrhage in lamina propria-submucosa.