A 15-year-old male terrier dog with symptoms of lethargy and severe abdominal distension was referred to the polyclinic hospital of the Ferdowsi University of Mashhad, Mashhad, Iran. In addition to numbness and abdominal distension, the dog also had anorexia and severe weakness and some skin masses were observed. Due to the enlarged abdomen, splenomegaly was diagnosed in ultrasonography. Fine needle aspiration was performed on the liver and skin mass and then, neoplastic lesions were reported based on cytology. On the necropsy, two masses were found on the liver and shoulder skin. These masses were well-encapsulated, soft and multi-lobulated. Samples taken from the liver and skin were prepared by Hematoxylin and Eosin staining and then, two different immunohistochemical markers were used to confirm the initial diagnosis. Histopathological examination of these two well-encapsulated, soft and multi-lobulated masses on the liver and skin showed lipid content and liposarcoma was indicated. Immunohistochemical staining using two markers, S100 and MDM2, made a definitive diagnosis and confirmed the diagnosis.