Osteosarcomas are highly aggressive tumors, characterized by local invasion/destruction and distant metastasis (spread to other organs).
Osteosarcoma commonly affects the appendicular skeleton (limbs) of large to giant breed dogs, but can also occur in the axial skeleton (skull, ribs, vertebrae, pelvis), which is a more common primary site in smaller dogs. Other bone tumors include chondrosarcoma, fibrosarcoma, hemangiosarcoma, liposarcoma, multiple myeloma, and metastatic bone tumors. The biological behavior, prognosis, and treatment of these tumors depends on tumor type, primary site (location), and extent of disease (stage). Therefore, various diagnostic tests such as radiographs (X-rays), bloodwork, and a biopsy are required to determine the most appropriate treatment.
The signs associated with a bone tumor may be nonspecific and depend on the primary site.
Tumors in the limbs often cause various degrees of lameness and pain, and a firm swelling may become evident as the tumor size increases. The pain can cause other problems such as irritability, aggression, loss of appetite, weight loss, whimpering, crying, sleeplessness, and reluctance to exercise. Tumors in non-weight-bearing bones may initially appear as a solid, firm mass. Other clinical signs may vary, depending on the primary site and involvement of underlying structures.