Feline Osteosarcoma

"Feline osteosarcoma (OS) is the most common primary bone tumor in cats. It can occur at any age and is seen more often in hind legs. Symptoms include problems you would expect when something is causing pain in the legs such as a limp. Treatment involves surgery, chemotherapy and radiation."

Osteosarcoma is a kind of bone cancer. It most commonly affects the long bones. Cancer may arise in the bones (primary osteosarcoma), or it may spread there from other locations (secondary osteosarcoma). It mainly affects older cats (ten years of age or up).

Osteosarcoma in cats is fairly rare. It is a fast-growing cancer, though, so if your cat shows symptoms of the condition, she needs to see a vet right away.

Feline Osteosarcoma Symptoms

Symptoms of osteosarcoma include limping and pain when walking. Cat owners often mistake the symptoms for signs of arthritis. By the time symptoms are visible, the cancer is often already fairly progressed, so it is important to get your cat to the vet right away if you notice her having difficulty getting around.

Feline Osteosarcoma Diagnosis

When you take your cat to the vet, she vet will examined thoroughly. Tests to expect include x-rays. A tumor will show up on the film. In order to confirm the diagnosis, a biopsy will be necessary. In this test, a small piece of the affected bone is surgically removed and examined for cancer.

Your vet will also take x-rays of your cat’s chest and abdomen to see if the cancer has spread to other organs, such as the liver or lungs. This is important as it may affect treatment.

Feline Osteosarcoma Treatment

With treatment, the median survival rate for cats with osteosarcoma is two years.

The most effective treatment for osteosarcoma in cats is excision (surgery). The affected area of the bone is removed. This may require amputating a limb, and cats generally cope well with amputation. In some cases, a technique called limb sparing may be used. In this procedure, the affected piece of the bone is removed and an allograft (a graft of tissue from a donor of the same species) is then inserted.

Radiation is often used as well in the treatment of osteosarcoma, particularly when limb-sparing procedures are used. It may also be used to treat cancer that cannot be completely excised.

Chemotherapy is generally used when cancer has spread to other organs, such as the liver or lungs. It may also be used to prevent cancer from spreading. There is some debate among veterinarians regarding the effectiveness of chemotherapy in cats after a limb has been removed. Caution should be used as cats are sensitive to the chemotherapy drug cisplatin. It can cause fluid accumulation in the lungs (pulmonary edema) which could threaten your cat's life. Other cancer agents that have shown some success in dogs include doxorubicin, liposome encapsulated muramyl tripeptides (liposome/MTP) and carboplatin.

Your cat can also be treated with pain medication to keep her comfortable. If she experiences side effects like nausea from chemotherapy, she can be treated with medication for that. Let your vet know if your cat appears uncomfortable. Cats tend to tolerate chemotherapy well.


Feline Osteosarcoma
Heldman, E., Anderson, M., Wagner-Mann, C.

Osteosarcoma Diagnosis and Treatment
Lorica, N.

Primary and Secondary Bone Tumors in the Cat 
M.H. Goldschmidt and D.E. Thrall


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