Bone Cancer in Dogs: Cause, Symptom and Treatment

An osteosarcoma is a form of bone cancer that mainly affects large dogs with long bones. Very painful, it manifests at the beginning by a simple intermittent lameness, but it must be quickly diagnosed and treated in order to avoid the expansion of the bone cancer in dogs and the formation of metastases. Find out the causes, symptoms and possible treatments if the disease is detected.

What is osteosarcoma in dogs?

Osteosarcoma is a primary bone tumor in dogs. It is the most common form of bone cancer in dogs, with almost 80% of bone cancers.

Osteosarcoma is a malignant tumor that affects the vast majority of large dog breeds. Some are also predisposed, such as the Irish Setter, the Borzoi (Russian Greyhound), the Scottish Deerhound, the German Shepherd, Saint Bernard, the Doberman, the Rottweiler, the Great Dane, the Irish Wolfhound, the Golden Retriever, and the Greyhound.

Generally, the disease affects dogs 10 years of age or older, but it can also affect some young dogs 18 to 24 months of age.

Generally, osteosarcoma is located at the end of the longest bones:

  • on the front legs, it is mainly located in the upper part (called proximal) of the humerus and in the lower part (called distal) of the radius,
  • on the hind legs, it is located in particular in the upper part (called proximal) of the tibia and in the lower part (called distal) of the femur.

However, certain cancers can form in organs such as the liver, lungs, spleen, digestive tract, intestines, breast tissue, reproductive system or even the eyes; they are then called extraskeletal.

What are the symptoms of osteosarcoma?

When a dog develops osteosarcoma, certain symptoms appear. The first and most common of these is lameness. It appears suddenly, then manifests itself intermittently for several days or weeks. Over the weeks, it becomes stronger and it evolves to get worse and become permanent. Lameness may be due to pain or a fracture that forms on the affected bone weakened by the tumor.

Lameness cannot be relieved durably and effectively by painkillers. It persists and the animal expresses discomfort because the pain is very pronounced with this type of cancer.

Other more general signs can be seen in dogs with osteosarcoma:

  • swelling of the bone: it is common to also see swelling in the limb that limps. This swelling is linked to a swelling of the tissue located near the bone affected by the tumor.
  • a drop in general shape: the dog loses weight, his muscles melt, he seems tired and he loses his appetite.
  • digestive disorders: the dog can manifest diarrhea and vomiting.
  • the more the disease progresses, the more the dog weakens and he can develop respiratory problems.

The diagnosis of bone cancer in dogs

When the first symptoms are noticed, it is advisable to consult the veterinarian quickly.

The specialist will start by performing a bone x-ray, the first examination that diagnoses this type of cancer. The x-ray allows him to observe the appearance of the dog’s bones, to note a fracture and to suspect osteosarcoma, or on the contrary to dismiss it. Depending on the profile of your animal (its age, breed, etc.) and the symptoms it develops, this first examination is sometimes enough to confirm that it is indeed osteosarcoma and that it is advisable to place a suitable treatment.

A bone affected by osteosarcoma manifests a loss of normal trabecular appearance. The periosteum, which is the membrane that envelops it, reacts strongly and the bone proliferates abnormally. Finally, lesions are seen at the ends of the affected bone.

If the doubt remains or if the veterinarian wishes to confirm the diagnosis, he can perform a bone biopsy. To do this, he punctures the bone marrow and analyzes the cells in the laboratory. This is a so-called histological analysis.

As a follow-up, the veterinarian can carry out an extension assessment, which is to say a scanner or an X-ray which will make it possible to detect the possible presence of metastases in the organism of the animal. However, it is not always possible to confirm the presence of metastases with this type of image. As nearly 90% of osteosarcomas metastasized at the time of diagnosis, it is common for veterinarians to establish treatment on the assumption that this is the case.

How to treat osteosarcoma in dogs?

It is possible to treat osteosarcoma in dogs, provided that they act quickly, as soon as the first symptoms appear.


The first treatment to consider is surgery. The veterinarian performs an amputation to remove all of the affected bone tumor in dogs. Amputation is not enough to cure cancer or increase the life expectancy of the animal. On the other hand, it brings comfort to the dog by eliminating the pain and it avoids the risk of proliferation of cancer.

Amputation is an operation well tolerated by dogs that adapt very quickly to their new condition. However, be aware that some dogs cannot be amputated, because they are too weak, too old, overweight, because the cancer is too widespread or because they have already had a limb amputated. Thus, before any surgical intervention, it is necessary to carry out a preoperative evaluation.

When amputation is performed, it is accompanied by chemotherapy in order to attack cancer more effectively.

Unfortunately, it is rare for an animal to survive osteosarcoma, because in 90% of cases, the diagnosis is made too late and metastases have developed. It is usually the related complications that lead to the death of the animal.

Some factors are important, including the age of the dog. Indeed, an animal from 8 to 10 years old will be more resistant than a young puppy or an old and fragile dog. The severity also depends on the size and location of the bone tumor in dogs.

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