What is osteosarcoma in dogs and cats?

Grace_in_flowers What is Osteosarcoma?

It's an aggressive malignant bone tumor that affects about 8,000 dogs in the US per year. It is more common in dogs than cats, and more common on larger dogs than smaller dogs. It also is usually less aggressive in cats if they do get it. Lucky cats.

There are two types of osteosarcoma:

Appendicular Osteosarcoma

    • accounts for 75%-85% of osteosarcomas
    • occurs in the limbs of large breed dogs such as Labrador Retrievers, Golden Retrievers, Rottweilers, Irish Wolfhounds, Saint Bernards, and Greyhounds.
    • average life expectancy without treatment is 4-6 months;
    • bone cancer can happen at most ages but tends to happen more in dogs 6 years old or older. It is more aggressive with a shorter life expectancy in younger dogs

Axial Osteosarcoma

    • this occurs in flat bones (skull, ribs, vertebrae, pelvis) but most commonly the jaw
    • it is more common in smaller dogs
    • a worse prognosis and shorter lifespan than appendicular osteosarcoma

What are the symptoms?

Osteosarcoma originates within the bone and migrates outward, which creates an explosion effect. Tumorous bone is very fragile and breaks easily (your vet would refer to as a pathologic fracture).

If your dog has this cancer, you will likely notice lameness and followed by a swelling in the leg, which gradually becomes extremely painful (signs: weight loss, aggression, loss of appetite, whimpering, sleeplessness, irritation and a reluctance to exercise.)

Diagnosis and Treatment

Your vet will usually spot a tumor by x-ray and blood work, and will treat the cancer by amputating the affected limb. Amputation not only removes the affected limb but removes the pain, radically improving the quality of your pet's life. Amputation is usually followed by chemotherapy to slow the cancer from spreading to other organs (metastacizing), particularly the lungs, which is the leading cause of death.

The most common chemotherapy agents used are:

There are other treatments in select cases such as:

  • Radiation therapy for pain relief
  • Limb saving surgery, where the bone containing the tumor is removed and replaced by a donor bone

As with any of your pet’s health conditions, if you are worried about your pet, talk to your vet.

Related posts:
toe tumors;
my cat or dog is limping;
and a beautiful story of dog friendship and caring in Grace's story and Grace's eulogy.
And finally, Hope for Hounds raising funds to fight Osteosarcoma over at the Embrace Pet Community blog