Glossary

Osteosarcoma

The most common bone cancer in dogs, an aggressive tumor that mainly affects large and giant breeds, often in a front leg.

Also called: bone cancer in dogs, canine bone cancer, osteogenic sarcoma

Osteosarcoma is a malignant tumor that grows from bone-forming cells. It makes up most bone cancers in dogs and tends to strike large and giant breeds in middle age or later, including the Greyhound, Rottweiler and Great Dane. It most often involves the long bones of the legs, especially near the shoulder and wrist or the knee.

The classic signs are lameness that does not go away, a firm swelling on a leg and pain. Because they resemble a sprain or arthritis, some dogs are first given rest for the wrong reason.

An X-ray often shows bone damage, and a biopsy confirms the cancer. Osteosarcoma spreads readily, often to the lungs, so staging tests matter. Any persistent limp in a large dog deserves a prompt veterinary exam.

Last reviewed November 8, 2026

In the index now

Related terms

X-ray An imaging test that uses a small amount of radiation to show a dog's bones, chest and belly organs. Biopsy The removal of a small piece of tissue, or a sample of cells, for examination under a microscope to find out what a lump or abnormal tissue is. Osteoarthritis A long-term, painful wearing down of joint cartilage that causes stiffness and reluctance to move, common in older and overweight dogs.