Objective: To classify histologic type and morphology of primary lung tumors in cats, to describe clinical findings in these cats, and to determine whether clinical findings were associated with histologic type or morphology.
Design: Retrospective study.
Animals: 86 cats with histologically confirmed primary lung tumors.
Procedure: Medical records for cats treated between 1979 and 1994 at any of 14 participating veterinary referral hospitals were reviewed.
Results: Weight loss, lethargy, and dyspnea were the most common clinical signs. Solitary or multiple pulmonary masses were seen on radiographs from 53 of 79 cats; effusion was seen on radiographs from the other 26. In 45 cats, tumors involved a single lung lobe. Caudal lung lobes were more commonly affected than were cranial lung lobes. Sixty-five cats had metastases. Tumors were classified as bronchial (n = 65), bronchiolar-alveolar (9), or other (12) and as poorly differentiated (59), moderately differentiated (20), or well differentiated (7). Breed, age, sex, weight, clinical signs, duration of clinical signs, and radiographic findings were not associated with histologic type or morphology.
Clinical implications: To identify possible occult primary lung tumors, thoracic radiography should be performed on cats with clinical signs of long duration, including weight loss, lethargy, and dyspnea.