Abstract
A 7-month-old, male jaguar presented with dyspnea and leukocytosis unresponsive to antibiotic therapy. Radiographs revealed unilateral pulmonary consolidation. An exploratory thoracotomy was performed, and the left lung, which contained a large multilobular mass with extensive fibrosis and numerous caseonecrotic foci, was removed. Microscopically, eosinophilic granulomatous inflammation surrounded broad (4.4–8.3 μm) rarely septate hyphae. A diagnosis of Pythium insidiosum infection was confirmed by immunohistochemistry, immunoblot serology, culture, and polymerase chain reaction. Dyspnea recurred despite treatment, and the animal succumbed 3 weeks after surgery. Necropsy findings indicated that death resulted from occlusion of the right main stem bronchus by a fungal granuloma. The oomycete P. insidiosum typically causes granulomatous disease of the skin or gastrointestinal tract in animals and arteritis, keratitis, or cellulitis in humans. Infection is uncommon in felines, and pulmonary involvement is rare. This report details the first case of P. insidiosum infection in an exotic felid and provides the first description of primary pulmonary pythiosis in any species.