Prognosis for Osteosarcoma in Dogs: Life Expectancy Considerations

Osteosarcoma in dogs is a type of cancer that occurs in the limb bones and less often in the spinal bones, the skull bones and the bones of the pelvis. The skeletal system that comprises of the limb bones is known as the appendicular skeleton while the skeletal system comprising of the bones of the spine, skull and pelvis is known as the axial skeleton. Osteosarcoma is the most common type of cancer and is more common in large dogs. It’s highly metastatic and easily spreads to other parts of the body.


Osteosarcoma is a bone cancer that develops deep in the bones. The bone is destroyed from the inside out and is more painful as the cancer progresses, resulting in lameness and swelling. An affected bone is weaker than a normal bone and can fracture as a result of minor injuries. Such fractures are known as pathologic fractures and these fractures don’t heal despite being treated. Appendicular osteosarcoma is more common than axial osteosarcoma and the rate of tumor growth is more rapid in such cancers. Axial cancer is more commonly found in smaller-sized, middle-aged dogs.

Causes of Canine Osteosarcoma

Although the cause is idiopathic, it has been observed that extra weight and force placed on bones can cause this cancer. It’s frequently found near growth plates and diets that promote rapid growth in puppies are a causative factor. Osteosarcoma also occurs at fracture sites where metal pins or plates are inserted. Irritation caused by the plate or pin is thought to cause cancer in such cases. Besides this, areas that have been exposed to radiation are also prone to the cancer.

Symptoms of Canine Osteosarcoma

  • Pain in bones
  • Lameness
  • Labored breathing
  • Cough
  • Fractures in bones as a result of mild trauma 
  • Intolerance to exercise

Prognosis for Osteosarcoma in a Dog

The average life expectancy of dogs with appendicular osteosarcoma that don’t receive treatment is 2 to 4 months. A dog that has been amputated and has had chemotherapy can expect to live for 10 to 12 months.

If the cancer has metastasized to the chest, the prognosis is much poorer and young dogs with osteosarcoma have more progressive forms of the disease with a shorter survival time. If the tumor is large and if the cancer has metastasized, the prognosis is poor. High levels of alkaline phosphatase that don’t normalize 40 days after surgery are also indicators of a poor prognosis.

According to research, a median survival time of 7 months was found in dogs that had radiotherapy along with chemotherapy and a median survival time of 8 to 12 months was found in dogs that had surgery and chemotherapy. 28 percent of the dogs in the study survived for 2 years after diagnosis when treated with both chemotherapy and surgery.

The prognosis for dogs suffering from axial osteosarcoma is not bright. However, the prognosis depends on the site of the cancer, the type of surgery performed and other treatment received. Animals with lower jaw cancer that have been operated upon can live for up to 12 months with no other treatment.

The pain experienced by pets suffering from Osteosarcoma can be managed with:

  • surgery
  • chemotherapy
  • radiation
  • pain medication
  • limb sparing surgery

Not all treatment options may be suitable for your pet and you should decide which treatment plan is best suited for dog after having a good discussion with the vet.