PNEUMOCYSTIS PNEUMONIA IN A DOG

Pneumonia due to Pneumocystis carinii was diagnosed in a 17-month-old neutered female Cavalier King Charles Spaniel with a four-week history of progressive dyspnoea. Radiographic and echocardiographic findings indicated primary pneumonopathy with increased pulmonary vascular resi stance resulting in cor pulmonale with tricuspid insufficiency. The an imal had a mild anaemia and moderate leucocytosis characterised by neu trophilia without left shift, lymphocytosis, monocytosis and absolute eosinopenia. Results from a transtracheal aspirate were inconclusive. At necropsy, all lung lobes were firm, solid and red-brown with 1-3mm irregular grey-white spots. The bronchial lymph nodes were enlarged an d moist but other lymph nodes and the spleen were small. Impression sm ears of the lungs revealed alveolar macrophages, neutrophils, and nume rous P. carinii trophozoites and nucleated sporozoites within cysts. H istopathalogically, the lungs showed a mixed pattern of bronchopneumon ia and chronic interstitial pneumonitis due to P. carinii. Bronchial, mesenteric and superficial cervical lymph nodes, and spleen showed lym phoid depletion. It was considered that immunodeficiency had predispos ed the dog to the infection but further investigation to confirm this was not undertaken.