Dirofilaria Immitis in Two Cats

Abstract

Two cats were diagnosed with Dirofilaria immitis infection in West Tottori. Case 1 had vomiting and dyspnea. Antigen testing for D. immitis yielded negative results, so the initial diagnosis in this case was pneumonia. The clinical signs resolved following administration of antibiotics. However, symptoms similar to those seen on the first visit were noted on a subsequent consultation after 348 days. On this occasion, antigen testing for D. immitis yielded positive results. Palliative therapy, including steroids, was initiated, but the cat died suddenly one week later. The initial diagnosis in Case 2 was pleural effusion secondary to heart failure. The animal was treated by another veterinary hospital, but there was no improvement. Antigen testing for D. immitis yielded positive results, and evidence of adult worms within the right atrium and right ventricle was provided by echocardiography. Following a diagnosis of caval syndrome, three female worms were removed by string brush via the left jugular vein. One day postoperatively, the clinical signs had resolved. This cat has subsequently been examined periodically and administered an appropriate prophylactic agent for D. immitis. Diagnosis of feline D. immitis infection is not straightforward. When a definitive diagnosis cannot be provided, it is important to interpret clinical findings very carefully, and to obtain informed consent for subsequent treatment, periodic reinspection, and prevention.