Primary cardiac fibrosarcoma with pulmonary metastasis in a Labrador Retriever

A 6-year-old, neutered male Labrador Retriever was diagnosed with congestive heart failure, and an echocardiogram revealed a large mass inside the pericardial sac associated with the left ventricle. At necropsy, the dog had marked ascites, mild hydrothorax, marked hydropericardium, and an 11.0 x 7.0 x 6.0 cm, tan and red, firm, well-demarcated mass attached to the left ventricular free wall. The mass was diagnosed as a fibrosarcoma based on the morphologic appearance and supportive immunohistochemical staining. To our knowledge, this is the first case report of a primary fibrosarcoma involving the left ventricular free wall myocardium, epicardium, and pericardium with a pulmonary metastasis in a dog.