Bone Cancer (Osteosarcoma) in Dogs: Signs, Treatment and Life Expectancy

Which Dogs Get Bone Cancer?

Large and giant breeds are most at risk, including Rottweilers, Great Danes, Greyhounds, Irish Wolfhounds, Scottish Deerhounds, Leonbergers, Dobermans, German Shepherds, Golden Retrievers, Boxers and Irish Setters.^4,5 The median age at diagnosis is about 7, though young dogs can be affected too.^3,1 Smaller dogs get osteosarcoma less often, and when they do it's more likely in the skull, ribs, spine or pelvis.^8,2

Most tumors develop in the legs, and the front legs are affected about twice as often as the back legs. The most common sites are the wrist end of the radius, the shoulder end of the humerus, and the bones above and below the knee.^10,7

Signs of Osteosarcoma in Dogs

• Lameness, often mild at first, coming and going, and briefly improving with pain medicine before getting worse^2,5,1
• Swelling over the bone, which may be firm and painful^7,8,4
• Pain, sometimes shown as irritability, whimpering, restlessness at night or reluctance to exercise^2,8
• A broken bone from little or no injury (a pathologic fracture)^7,1
• Reduced appetite and weight loss^2,4
• Jaw tumors may cause swelling, drooling and trouble opening the mouth⁴

Limping is usually caused by arthritis or a strain, but persistent lameness in a large dog should be checked, especially if it isn't improving.⁶

Diagnosis

• X-rays of the leg often show a typical "moth-eaten" pattern of bone destruction and new bone growth.^7,4
• Chest X-rays or CT look for visible spread to the lungs.^7,9,2
• A needle sample or bone biopsy confirms the diagnosis. Some vets proceed straight to amputation when the age, breed, location and X-ray appearance strongly point to osteosarcoma, then examine the removed bone.^2,5
• Blood tests, including alkaline phosphatase (ALP); a high ALP level is linked to a poorer outlook.⁷

Treatment Options

• Amputation is the standard way to remove the tumor, and it removes the source of the bone pain.^7,8,4 Most dogs walk on their own within 12 to 24 hours and adapt well to life on three legs, usually within about a month. Your vet will check that your dog's other legs and joints can cope.^1,2,11
• Chemotherapy after surgery is nearly always recommended because the cancer has usually already spread microscopically.⁴ Carboplatin is the most common drug, typically given every 3 weeks for four to six treatments. Dogs tolerate chemotherapy much better than people; estimates of how many need a hospital stay for side effects range from under 5% to about 15%, depending on the drug.^2,1,4 In one trial, carboplatin alone kept dogs disease-free longer than alternating carboplatin with doxorubicin.¹²
• Limb-sparing surgery is an option for some tumors at the wrist end of the radius, but complications such as infection are common.^2,1
• Stereotactic radiation uses a few high doses to destroy the tumor while keeping the leg, though the weakened bone can still break.^2,13
• Palliative care for dogs that can't have or don't want surgery: pain medicines, palliative radiation (which helps about 75% of dogs for an average of 2 to 4 months) and bisphosphonate drugs that slow bone destruction.^2,7

Osteosarcoma Life Expectancy

These are typical median survival times from published sources. Individual dogs can do better or worse, and your oncologist can estimate your dog's outlook.

• No treatment: about 1 to 2 months, usually because of pain or fracture⁷
• Amputation alone: about 3 to 6 months^7,3,8,5
• Amputation plus chemotherapy: about 9 to 12 months, and roughly 20% to 25% of dogs live longer than two years^7,2,3,5
• If spread is already found at diagnosis: one older report gives a median of about 2½ months¹⁰

Most dogs eventually die from spread of the cancer to the lungs.^7,8 Fewer than 25% of dogs with osteosarcoma of the leg are cured.¹

Does Neutering Affect Bone Cancer Risk?

A study of Rottweilers found that dogs neutered before 1 year old had a higher rate of bone sarcoma than intact dogs.¹⁴ Other studies weren't able to look at osteosarcoma on its own, and their cancer findings varied widely by breed.^15,16 If you have a large or giant breed, discuss the timing of spaying or neutering with your vet.¹⁷

Quality of Life and When to Say Goodbye

Bone cancer is painful, so good pain control is essential.⁴ For dogs on palliative care alone, pain medicine often stops working after weeks to a few months.⁵ Signs it may be time to consider euthanasia include pain that can't be controlled, a broken bone, trouble breathing (which can mean spread to the lungs), and a dog that no longer eats or enjoys life.⁵ A quality-of-life scale can help you and your vet decide.¹⁸

Frequently Asked Questions

How long does a dog have to live with osteosarcoma?

It depends on treatment. Typical medians are about 1 to 2 months without treatment, 3 to 6 months with amputation alone, and 9 to 12 months with amputation and chemotherapy, with about 1 in 5 dogs living longer than two years.

What are the first signs of osteosarcoma in dogs?

Usually a limp that comes and goes or doesn't fully go away, sometimes with a firm, painful swelling on the leg. It often improves briefly with pain medicine before getting worse.

Is it worth treating osteosarcoma in dogs?

Many families find it is. Amputation removes the pain, most dogs adapt quickly to three legs, and chemotherapy can extend good-quality life. Palliative care is a reasonable choice too. Discuss your dog's age, health and your goals with your vet.

Is my dog in pain with bone cancer?

Bone cancer is painful. Limping, whimpering, restlessness at night and irritability can be signs. Your vet can provide pain relief, and amputation or radiation can relieve pain directly.

What can be mistaken for osteosarcoma?

Arthritis and muscle or ligament injuries are much more common causes of limping. X-rays and sometimes a biopsy are needed to tell them apart, which is why persistent lameness in a large dog should be checked.

How do dogs cope after leg amputation?

Most dogs walk within a day of surgery and adapt to three legs within about a month, including large dogs. Many return to most of their usual activities. Your vet will check that the other legs and joints can cope first.