Chondrosarcoma in Cats

Chondrosarcoma is a type of bone cancer that affects connective tissue between joints and cartilage and bone tissues. This tumor commonly affects nasal passages, ribs, and sometimes limbs in cats. In the nasal passages, tumors invade cartilage, connective tissue, and nasal bones and cause problems with breathing and swallowing. Chondrosarcoma in the ribs may migrate to lung tissue nearby. Complications of chondrosarcoma tumors in the limbs occur due to fractures caused by rapidly growing tumors. Chondrosarcoma is an invasive cancer and is life-threatening if not caught early. It can metastasize to other parts of the body and early intervention by a veterinarian is required. 

Symptoms of chondrosarcoma are similar to those of other cancers, but are also a function of the area of the body damaged by the tumors. Depending on their location and type, tumors may be fast spreading or slow but are nevertheless invasive regardless of the speed with which they develop.

General symptoms of chondrosarcoma in cats are:

• Lethargy
• Intolerance to exercise
• Collapse
• Loss of appetite

If tumors are affecting a limb, symptoms include:

• Pain in the limb
• Lameness
• Swelling of limb where the tumor occurs
• Fracture in the bone from tumor growth

Chondrosarcoma in the cartilage, connective tissue, or bones in the nasal passages or throat can cause:

• Sneezing
• Breathing difficulties/noisy breathing
• Changes or loss of voice or purr
• Nosebleeds
• Nasal discharge
• Discolored mucous membranes (bluish in color)
• Difficulty swallowing
• Coughing
• Tearing of eyes
• Facial deformity
• Bad breath

Other symptoms may occur if metastasis occurs, depending on the area affected.

The cause of chondrosarcoma is not known, however, some factors have been associated with an increased incidence. Cartilaginous growths seem to be associated with a higher incidence and some chondrosarcomas appear at the site of a previous fracture which may predispose your pet to this disease. As well, as an increased incidence has been shown in urban dwelling cat populations, perhaps because they are exposed to more pollution. Viruses have been found in some of the cancerous cells affecting bone and there may be an association with viral infection. In addition, neutered cats and Siamese cats appear to be more prone to this type of cancer.

Your veterinarian will perform a physical examination on your cat to discover any growths, areas of pain or swelling and observe symptoms. Your vet will ask you about the onset and extent of symptoms observed as well as for a detailed medical history of your pet. Many other conditions can cause similar symptoms, so your veterinarian will try to rule these out based on the physical exam and the information you provide.

A urinalysis and blood count are commonly performed, however, cats with chondrosarcoma usually show normal findings in these areas. Because some chondrosarcomas are slow growing, they may be mistaken for benign tumors. A lymph node biopsy may show signs of immune system response, which can point your veterinarian to the possibility of chondrosarcoma. X-rays and CT scans may show tumors or abnormalities in bones and tissues. If your veterinarian locates a growth, a biopsy of the growth will be taken for a confirmed diagnosis of chondrosarcoma.

Because chondrosarcoma is an aggressive and malignant cancer, euthanasia may be recommended. Treatment is only possible if caught early and before the cancer has metastasized to other parts of the body.

For localized chondrosarcoma of the limbs or ribs, radiation therapy and surgery consisting of the removal of the affected limb or the rib and lung tissue nearby can be a successful treatment. If chondrosarcoma occurs in the nasal passage, radiation therapy has been effectively used to reduce tumors. The effectiveness of chemotherapy on this type of cancer is not known.

Supportive care and medications to relieve symptoms can be provided by your veterinarian.

Radiation therapy is associated with some side effects, primarily skin irritations, and you may need to take precautions against your cat scratching irritated skin and worsening the condition . Your pet will need to recover from surgery if it was performed. Cats recovering from surgery need rest and restricted movement. Pets who were treated for tumors in the nasal passages may need tube feeding until recovered. Pain medications are commonly prescribed ad should be administered as directed.