What You Need to Know About Osteosarcoma in Dogs

Another name for bone cancer, osteosarcoma is the most common form of cancer in dogs – and the most aggressive. Here’s what you need to know about osteosarcoma.

One of the most common causes of death in dogs is cancer, affecting roughly 50% of dogs over the age of 10. Cancer comes in many forms and, according to the American Animal Hospital Association, osteosarcoma is one of the most common. Osteosarcoma is simply another name for bone cancer and an aggressive one at that. Keep reading to learn more about osteosarcoma in dogs including what it is, the symptoms, and treatment options.

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Understanding Osteosarcoma in Dogs

Though osteosarcoma can affect any dog, it is most commonly seen in dogs over 8 years of age and dogs that weigh more than 90 pounds. Some of the breeds most at-risk for osteosarcoma include Great Danes, Doberman Pinschers, Saint Bernards, Rottweilers, Golden Retrievers, and German Shepherds. Some factors that can increase a dog’s risk for developing this type of bone cancer include:

• Rapid growth rate in large- and giant-breed puppies
• Repaired fractures with metallic implants
• Gender (males have a risk 20% to 50% higher than females)
• Early age spaying or neutering
• Trauma to the bone, particularly blunt bone injury

In the early stages of the disease, symptoms are often mild and easy to confuse with other conditions. Many dogs present with swelling, intermittent lameness, and bone or joint pain. As the condition progresses, the dog may become lethargic and may lose his appetite.

Related: What is Digital Squamous Cell Carcinoma in Dogs?

The longer the cancer develops in the bone, the weaker the bone becomes and the risk for facture increases exponentially. The location of the tumor itself may also produce specific symptoms. For example, when the tumor forms in the dog’s jaw, he may have trouble chewing or opening his mouth. The pain increases as the tumor grows as well, and lameness usually develops within 1 to 3 months of onset.

How is it Diagnosed and Treated?

The primary diagnostic tests for osteosarcoma include x-rays and histopathology. In an x-ray, bones that are affected by osteosarcoma will have an obvious moth-eaten appearance and a bone biopsy will be taken to confirm the diagnosis. Unfortunately, by the time the dog displays symptoms severe enough to warrant testing, the cancer has probably progressed to the point where the dog’s prognosis is poor. Though some dogs survive 5 to 6 years after diagnosis, a survival time of 1 year is only achieved in about 50% of dogs who are treated for osteosarcoma.

Depending where the tumor is located and how much damage it has done, treatment options may include surgery or chemotherapy. Surgery may involve removal of the tumor alone or it could be a complete amputation of the limb. Chemotherapy is only administered in cases where the tumor has been removed – it is completely ineffective in dogs who are not good candidates for surgery. Radiation therapy is usually reserved as a palliative treatment to reduce pain and discomfort.

Osteosarcoma is a very aggressive disease, so you should never ignore the warning signs. If you have a large or giant-breed dog, particularly one that is getting older, and he starts to develop signs of bone or joint pain or swelling, it is always best to have it checked out rather than take the risk.