Canine axial skeletal osteosarcoma. A retrospective study of 116 cases (1986 to 1989).

Axial skeletal osteosarcomas were evaluated retrospectively in 116 dogs. Thirty-one tumors occurred in the mandible, 26 in the maxilla, 17 in the spine, 14 in the cranium, 12 in the ribs, 10 in the nasal cavity and paranasal sinuses, and 6 in the pelvis. Medium-sized and large dogs were most commonly affected. Females outnumbered males 2.1:1, but this varied with tumor location. The mean age was 8.7 years. Osteosarcomas of the rib occurred in significantly younger dogs (mean age, 5.4 years) than osteosarcomas at any other axial skeletal site. Pulmonary metastasis was diagnosed radiographically in 11.1% of the dogs. The median survival for dogs treated surgically was 22 weeks, the 1-year survival was 26.3%, and the 2-year survival was 18.4%. The tumor recurrence rate was 66.7%. Most dogs (79.6%) died or were euthanatized for problems associated with the primary tumor.