Primary pulmonary osteosarcoma treated by thoracoscopy-assisted lung resection in a dog.

A 6-year-old female, intact boxer presented with acute respiratory distress due to a mass in the left cranial thorax. The tumor, which originated in the left lung and was shown by histology to be an osteosarcoma, was removed by lateral thoracotomy. The dog died from unrelated disease 7 mo later and no tumor was evident at necropsy.