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Osteosarcoma in Dogs

dog being treated in veterinary hospital


Osteosarcoma is a type of cancer in dogs. It strikes the bone but can affect other areas as well. If your dog has been diagnosed with this condition or you simply want to be informed, here is more about osteosarcoma in dogs. What it is, why it happens, how it is diagnosed and treated, and what you can do to make your dog more comfortable.

What is Osteosarcoma?

According to VCA Hospitals:

Osteosarcoma is a malignant tumor of the bone. This cancer has the same appearance as human pediatric osteosarcoma. Osteosarcomas are tumors that arise from the abnormal production of cells that create and break down bone (called osteoblasts and osteoclasts, respectively). The long bones (arms and legs) are the most commonly affected, though bones such as the jaw, hips, or pelvis may also be affected. Osteosarcoma can also affect non-bony tissues, including the mammary glands, spleen, liver, and kidneys. This is called extraskeletal osteosarcoma.

This cancer usually affects the leg bone and it seems to happen in dogs that are either older or at least middle-aged. Yet, it can happen at any age.

Veterinary Partners states:

Osteosarcoma can develop in any bone but the limbs account for 75-85 percent of affected bones. Osteosarcoma of the limbs is called appendicular osteosarcoma. It develops deep within the bone and becomes progressively more painful as it grows outward and the bone is destroyed from the inside out.

Why Do Dogs Get Osteosarcoma?

There is not a specific or single cause for this type of cancer – much like many types of cancer, even in humans. There may be risk factors such as the fact that it seems to happen to larger breed dogs than smaller dogs. There are also those breeds that seem to be predisposed to osteosarcoma. These include:

In some cases, dogs that have had a blunt bone injury seem to have increased numbers of osteosarcoma but those numbers are slight.

What Are the Symptoms?

There are a few symptoms to be aware of that include limping, lethargy, loss of appetite, or swelling. The main symptom is pain. This is a condition that causes a lot of pain in dogs and causes inflammation that is hot to the touch.

How Is It Diagnosed?

There are a few tests that help diagnose osteosarcoma in dogs. The main one is x-rays. The other tests include biopsies, CAT scans, bone scans, and blood tests.X-rays help locate lytic lesions which are areas that the cancer has eaten away. It is easy to know which limb on the dog to look at since as mentioned, this will be a tender area.

These may be expensive without pet insurance, which is why it is a good idea to have this as a backup plan if you have a dog.

If an x-ray does show that it may be osteosarcoma, the vet may need to do further testing such as a fine needle aspiration. What he will do is take a sample of the cells directly from the area using a syringe that is attached to a small needle. Then he can send it to the lab to be inspected under a microscope.

What is the Prognosis?

Unfortunately, the prognosis for this disease is not always a good one. What happens in almost 100 percent of cases is that the disease metastasizes. What this means in layman’s terms is that the cancer cells spread elsewhere. They may not even be able to be seen but they are affecting various parts of the dog.

There is what is known as staging and what this is is more tests like urinalysis, other x-rays, and blood tests. In some cases, an abdominal ultrasound is needed. Lymph nodes are also checked to see if there is swelling or that they are enlarged, which also indicates spreading.

If the cancer has not spread, there are options to localize it. This means that the limb may be removed with amputation. It may be upsetting or difficult for the dog owner but most dogs do quite well after an amputation and it can save their life. If it is safe to do so, surgery is an option as well.


After any surgical procedures, chemotherapy is recommended to keep the cancer controlled and in some cases, radiation therapy is also recommended. Just like in people, these are some of the ways osteosarcoma is treated in dogs.

The most important thing after making a decision on treatment is pain control. Since this is a painful cancer it is imperative to ensure that your dog has access to medication that helps relieve the pain. This can be discussed with your vet to find out the suggested regimen for your dog’s care.

Treatment may include surgical amputation, chemotherapy and radiotherapy.

Cost to Treat: $5,000 to $20,000

Making Important Decisions

Your dog having cancer is never easy, especially an aggressive kind like osteosarcoma. It is important to look at the best options for your dog’s well-being. Your vet can help you make the right decisions but it will all depend on the severity of the cancer. In some cases, it may be best to make the decision no one wants to make. If the cancer has not spread far and there is hope for a normal life, then veterinary care can help extend your dog’s like and keep him happy and healthy.

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