Osteosarcoma at the site of a cortical bone allograft in a dog.

An osteosarcoma developed in the proximal femur of a 9-year-old female Great Dane. The femur had been fractured 5 years previously and was stabilized with plate fixation with the incorporation of a frozen cortical bone allograft. The dog recovered without complications after the surgery and had normal use of the leg before the osteosarcoma developed. The tumor had metastasized to the lungs, spleen, and ipsilateral popliteal lymph node.