Joint Cancer (Synovial Sarcoma) in Dogs

Joint cancer causes pain and swelling of the affected limb, which can eventually affect your dog’s ability to walk. You may also be able to see or feel a lump in the area where the tumor is located. Since cancer symptoms can be varied, joint cancer can be hard to diagnose. Prompt and aggressive treatment are vital to eradicating a possible tumor.

Joint cancer is a connective tissue and joint disease that is not often seen in dogs. This form of cancer can be very aggressive and usually spreads fast, so prompt treatment is essential for your dog’s health.

The symptoms of joint cancer will vary depending on the joint(s) that are affected. Most of the time you will notice your dog having trouble walking and not playing as much as usual.

• Limping
• Swelling
• Pain
• Ulcerated sore in affected area
• Fever
• Loss of appetite
• Losing weight
• Difficulty breathing if cancer spreads to the lungs

There is no known cause of joint cancer, but it is found most often in large types of dogs. The reason is unknown, but the most common dogs affected are Golden Retrievers, Saint Bernards, Irish Setters, Great Danes, Boxers, Rottweilers, and German Shepherds. Although this cancer can affect any joint in your dog’s body, the common areas are the joints that carry the most weight, such as the elbow, shoulder, and hip. Research has found that this cancer often presents in or near a bone that has been previously fractured, but there is not enough evidence to support this as of yet.

Your veterinarian will need to know what symptoms you have noticed and when you first noticed them. He will do a physical examination and he may be able to feel the tumor during the exam. He will order a CBC and blood chemistry panel, digital radiographs (x-rays) of the affected area.

 A biopsy is necessary to determine if it is cancer. This can be done by withdrawing a sample of tissue from the tumor and the surrounding lymph nodes with a syringe. This tissue will be microscopically checked for cancer cells.

 If he thinks the cancer has metastasized, he will order x-rays of your dog’s entire body and possibly an MRI and ultrasound to find where it has spread. It is important to know how far the cancer has progressed before deciding on the right treatment protocol.

If the cancer is just in one joint of the hip, elbow, or ankle, the vet will probably want to amputate to prevent the cancer from spreading. Even after the amputation, it is possible the cancer will represent in other joints so the veterinarian will have you see an oncologist about preventive treatment.

 The oncologist will examine your dog and your dog’s x-rays before starting any kind of treatment. This usually includes several rounds of radiation and possible chemo treatments to slow the progression of the disease.  

The prognosis for joint cancer is not good at this time with the two-year survival rate less than 50% in cancer that has spread to other areas of the body. Chemo and radiation can slow the progression and make your dog more comfortable, but many owners choose euthanasia within 6 to 12 months. There are many clinical trials for cancer in dogs that can prolong his life. If you are interested, ask your veterinarian or oncologist for more details and a recommendation.