Diagnosis of pneumocystis pneumonia in a 2-year-old King Charles Cavalier Spaniel using the polymerase chain reaction.

A 2-year-old, female spayed, King Charles Cavalier Spaniel was presented for evaluation of dyspnea, inappetence, and lethargy. Thoracic radiographs revealed a moderate diffuse interstitial lung pattern affecting the perihilar and caudodorsal lung fields, and an echocardiogram revealed severe pulmonary hypertension. A bronchoalveolar lavage (BAL) was performed, and cytology revealed mixed inflammation with cysts and trophozoites consistent with Pneumocystis. Pneumocystis infection was later confirmed with PCR. To the author's knowledge, this report represents the first case of canine pneumocystis pneumonia diagnosed antemortem with PCR from a BAL sample. Pneumocystis represents an important, but uncommon cause of afebrile pneumonia in immunosuppressed dogs.