What It Is:
Osteosarcoma is a malignant bone cancer that develops from the cells responsible for forming and maintaining bone. It is most commonly found in the limbs, but it can also appear in the skull, spine, pelvis, or ribs. Although more common in dogs, osteosarcoma does occur in cats, usually in middle aged to older cats.
Unlike dogs, cats with osteosarcoma have a lower risk of metastasis and may have a better prognosis with early detection and treatment.
🐾 Common Symptoms
Symptoms vary based on the tumor’s location, but may include:
- Lameness or limping
- Swelling over a bone or joint
- Pain when the area is touched
- Reduced activity or reluctance to jump or climb
- Loss of appetite
- Weight loss
- Behavioral changes due to chronic pain
- Neurological signs if the tumor is on the spine or skull
In some cases, the tumor may weaken the bone and cause a pathologic fracture.
🦠 Causes and Risk Factors
The exact cause of osteosarcoma is unknown, but contributing factors may include:
- Genetics or breed predisposition
- Previous trauma or fractures
- Chronic inflammation or bone infections
- Radiation exposure in rare cases
There is no known way to prevent osteosarcoma. It is a spontaneous cancer that can develop in otherwise healthy cats.
🔍 Diagnosis
Osteosarcoma is usually suspected based on physical signs and imaging, then confirmed with tissue testing.
Diagnostic steps include:
- X rays to detect bone destruction or abnormal growth
- CT scan or MRI to evaluate the tumor’s extent
- Fine needle aspirate or biopsy to confirm the diagnosis
- Bloodwork and urinalysis to assess overall health
- Chest X rays to check for lung metastasis
- Bone scan in advanced cases or for surgical planning
Other bone tumors and infections must be ruled out before a final diagnosis is made.
💊 Treatment
Treatment depends on the tumor’s location and the cat’s overall condition. Options may include:
- Surgical removal of the tumor, often through limb amputation if the leg is involved
- Wide excision of skull or rib tumors when possible
- Pain management with medications such as gabapentin, NSAIDs, or opioids
- Chemotherapy, though it is less commonly used in cats due to lower metastasis risk
- Radiation therapy in select cases
- Palliative care when surgery is not an option
Most cats recover well from amputation and can live a normal life with three legs.
🩺 Prognosis
The prognosis varies based on the tumor’s location, completeness of removal, and presence of metastasis:
- Limb osteosarcoma has a fair to good prognosis after surgery, with survival ranging from six months to two years or more
- Axial tumors (in the skull or spine) are harder to remove and have a more guarded prognosis
- Metastasis is rare in cats, which improves long term outcomes compared to dogs
Early diagnosis and treatment significantly improve quality of life.
💡 Cat Owner Note
Hearing the word cancer is scary, especially when it affects the bones. But osteosarcoma in cats behaves differently than it does in dogs, and in many cases, surgery can give your cat a second chance at comfort and mobility. If your cat is limping or has a lump on a bone, don’t wait. A vet visit could make all the difference.
❓ Frequently Asked Questions About Osteosarcoma in Cats
Is osteosarcoma painful for cats?
Yes. It causes inflammation and bone destruction, which can be very painful without treatment.
Can cats live after amputation?
Yes. Most cats adapt very well to life on three legs and resume normal activities after recovery.
Does osteosarcoma spread in cats?
It can, but it spreads much less often in cats than in dogs.
How is osteosarcoma treated?
Surgery is the most effective treatment. Pain management and supportive care are also essential.
Can osteosarcoma be cured?
It can be controlled or removed in many cases, especially if caught early. Some cats live more than two years post surgery.
What is the difference between osteosarcoma and other bone lumps?
X rays and biopsy are needed to distinguish osteosarcoma from other bone conditions like abscesses or benign tumors.