Pulmonary pythiosis in a canine patient.

A Staffordshire terrier presented for evaluation of a chronic, nonproductive cough that was unresponsive to antibiotic therapy. A large mass identified in the pulmonary hilum was most consistent with tracheobronchial lymphadenopathy on radiographic and computed tomography (CT) images. Bronchoscopy confirmed a mass compressing the dorsal portion of the intrathoracic trachea. Bronchoscopic biopsies of the tracheal mass revealed necrosuppurative and eosinophilic inflammation with intralesional Pythium insidiousum hyphae. Pythiosis should be included as a differential diagnosis for tracheobronchial lymphadenopathy and bronchopneumopathy in dogs, especially when the patient is from or has visited a region endemic for Pythium insidiosum.