Bone Cancer in Dogs

Like in people, not all dog cancers are the same. The soft, fatty tumors that can develop on your older dog’s skin are often benign and pose no harm to your pup’s quality of life. But tumors that form internally may be harmful, painful, and can spread to other parts of the body. Bone cancer is one such type of malignant cancer.

Cancer occurs when cell proliferation goes unchecked. Abnormal cells accumulate and form tumors depending on the organ from which they originate. In the case of bone cancer, cells within the bone can grow out of control and form large, painful lesions.

Osteosarcoma is the most common type of bone cancer. It accounts for 95% of all cases and comes from the types of cells that are responsible for building up and breaking down bones. Osteosarcoma primarily affects long bones like those in the forelimbs and hindlimbs but can grow in other places like the hips.

There are environmental and inherited factors responsible for its development, and large breeds like Great Danes, Golden Retrievers, Labrador Retrievers, and Rottweilers have an increased risk for it. Osteosarcomas have a high risk of spreading to other internal organs, especially by the time it has been diagnosed via x-rays and biopsies.

The second most common type of bone cancer is chondrosarcoma. This bone tumor affects flat bones such as those around the nose, skull, and ribs. It originates from the cells that create cartilage in the joint spaces. It is less likely to metastasize to other parts of the body, but it is still locally aggressive and can tremendously painful.

Fibrosarcomas and hemangiosarcomas are some other types of cancer. Both are primarily soft tissue tumors, originating from connective tissue and blood vessels, respectively. But in rare cases, fibrosarcomas and hemangiosarcomas can originate from the bone.

If your canine companion develops bone cancer, he may start out limping as if he sprained his leg. It is common for veterinarians to prescribe an anti-inflammatory at first, but if the limping persists, your pup’s illness might not be as simple as a sprain.

When bony tumors become larger, they can cause noticeable firm swelling that pushes the skin upward. For example, you might notice a large bump near your dog’s shoulder or his wrist. The swelling itself can be extremely painful and cause continued limping despite use of pain medications.

Bone cancers tend to eat away at the healthy bone, and this makes the bone susceptible to fractures. Pain from thesepathologic fractures can be so severe that your dog may appear lethargic, and he might not want to walk or eat or drink.

Most veterinary cancer specialists agree that it is good practice to check your dog for lumps or bumps at least once a week. If you find a new bump, make a note of its size and location. Then, make an appointment with your veterinarian to get it checked out.

For suspected bone cancers, x-rays are necessary to evaluate the affected bone. Tumors will appear as moth-eaten and sometimes very large bony lesions. In severe cases, bony tumors can cause fractures which can also be confirmed via x-ray.

Fine needle aspirate testing can often be performed to test the tumor. This is achieved via a needle and syringe. Cells are collected from the tumor and evaluated by a pathologist. If the cell sample is not sufficient for a definitive diagnosis, a biopsy sample is necessary.

Bone tumors are so aggressive because of their potential to spread to other body parts, even well beyond the site where they develop, and they can be far-reaching by the time you’ve confirmed it via testing. Surgery is necessary in order to remove the tumor. Not only does this eliminate the chances of further cancer spread, but it also greatly mitigates the bone pain that they experience. Treatment is then followed up with chemotherapy and certain kinds of radiation therapy.

If surgical removal is not possible due to the tumor location, chemotherapy alone may help. However, it does not provide as long of a median survival time as surgery with chemo. The former offers four to six months while the latter offers 12 to 18 months.

Multi-modal pain management is often necessary to help dogs with bone pain. Non-steroidal anti-inflammatories, opioids, and nerve pain medications like gabapentin can provide some relief.

Bone cancer is one of the most severe forms of cancer. Not only can it be very painful to deal with, but it can also rapidly spread to other parts of the body. Early diagnosis is key to helping your pup feel better faster, so be sure to contact your veterinarian if your dog is ever limping or showing signs of pain.

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