An Overview of Osteosarcoma in Dogs

Osteosarcoma is the most common bone tumor cancer found in both dogs and man with approximately 10,000 new cases diagnosed in the United States each year for dogs and 2,000 for humans.

More Likely in Large Breeds

Primarily affecting middle-aged large and giant purebred dogs, osteosarcoma is a highly aggressive and painful cancer. Dogs weighing over 80 pounds are 60 times more likely to develop an osteosacoma than dogs weighing 75 pounds. It is also more common in males.

Though osteosarcoma type cancer accounts for only 5% of all canine bone cancer tumors, it accounts for 80-90% of malignancies involving the bone. Often it requires amputation of the affected limb together with chemotherapy to provide temporary relief from this very aggressive disease.

Common Sites

Though osteosarcoma can affect the bones of the spine, ribs or skull, it is most prevalent to the bones of the limbs (appendicular osteosarcoma) away from the elbow and close to the knee or in the "wrist" or shoulder, accounting for 75 to 80% of the cases. As the dog bone tumor progresses, there is more pain and swelling causing dog lameness, often the first symptom a dog owner notices.

Originating deep with the bone, osteosarcoma becomes progressively more painful as the tumor grows outward, destroying bone from the inside out and replacing it with tumorous bone. Since tumorous bone is weaker than normal bone, minor injuries can actually cause bone fractures. These pathologic fractures will not heal so "casting" the break or performing any surgical procedures will not work.

Treatment of Oteosarcoma

A physical examination, blood work, X-rays of the bone and lungs, and a biopsy is needed to indicate whether osteosarcoma is present. The X-ray of the lung is necessary in determining whether the cancer has spread (metasasis). Approximately 90% of all new diagnoses have already spread to the lymph nodes or the lungs, resulting in the dog coughing or gagging.

Usually the only treatment available is the amputation of the affected limb; however, limb-sparing procedures may be an option in a few cases. Limb-sparing procedures remove the primary tumor, which not only is a source of pain but also the source of spreading the disease. Recovery from surgery and the adaptation to life as an amputee is generally quick. Radiation therapy to control pain is sometimes necessary.

The tumorous bone can also be replaced by a bone graft from a bone bank or with a "re-growing bone" technique called "bone transport osteogenesis". The joint nearest the tumor is fused and cannot be flexed. Limb-sparing procedures can only be done on the lowest parts of the leg when no more than 50% of the bone is involved and when no muscles are involved. Complications, such as bone implant rejection and fractures, are still possible.


Chemotherapy is usually begun after amputation. This is to relieve pain and reduce the possibility of the spread of the tumor. Carboplatin and cisplatin are the most successful drugs available with carboplatin the more expensive but safer one to use. Sometimes doxorubicin is combined with cisplatin. Each medication has its own advantages and disadvantages. Pain relief is found with tramadol, gabapentin, amantidne or non-steroidal anti-inflammatory (NSAID) medications, such as rimadyl, deramaxx, etogesic or metacam, or in combination.

Unfortunately median survival rates vary but are often less than one year; however, some survivors live a year or longer.