Case report 775. Canine osteosarcoma with associated avascular necrosis and sequestrum formation.

A young dog was found to have an osteosarcoma of the proximal femur containing a radiologically evident sequestrum of dead bone. Although the tumor was extensive, the plain films were most remarkable for the presence of a sequestrum. MR scans revealed the extent of the lesion, with low signal throughout the lesion consistent with the heavily calcified tumor and central avascular bone. At the 1-year follow-up, lung metastases had developed, but the dog appeared well.