Paraneoplastic hypertrophic osteopathy in a Great Dane with rib sarcoma

An 8-year-old female-spayed Great Dane was referred for further investigation of a 1-month history of stiff gait, pain on palpation of the limbs, weight loss and pyrexia. Investigations revealed a generalized soft tissue swelling along the long axis of the forelimbs and to a smaller extent on the hindlimbs. CT identified a mixed osteolytic and osteoproliferative mass originating from the second right rib. CT also showed characteristic features of hypertrophic osteopathy along the forelimbs and proximal hindlimbs. Cytology of the rib mass was consistent with an aggressive sarcoma. To the authors' knowledge, this is only the second documented case of hypertrophic osteopathy associated with rib sarcoma without evidence of lung metastasis.