Although it’s more common in older dogs and larger breeds, bone cancer can strike dogs of any age and size.
The most common and aggressive form is osteosarcoma. Osteosarcomas account for more than 80 percent of bone tumors in dogs. The tumors usually occur in the long bones of the limbs, although they can affect any bones in the dog’s body.
Osteosarcomas are hard, bony tumors. The tumors are likely to metastasize (that is, spread to other organs in the body). One of the most common causes of death from bone cancer is metastases to the dog’s lungs.
Besides osteosarcoma, other forms of cancer that affect the bones are chondrosarcoma, which originates in cartilage; fibrosarcoma, which affects fibrous connective tissue; and synovial cell carcinoma, which originates in joint tissues.