Fibrosarcoma (FSA) in Dogs (Bone)

Overview of Canine Bone Fibrosarcoma

Fibrosarcoma, commonly abbreviated as FSA, is a type of cancer that arises from the fibrous connective tissues of the skull, spine, pelvis and ribs but can arise from any bone that can occur in dogs. This cancer is a part of a group of tumors that would be termed non-osteosarcomas of bone and can sometimes be very difficult to distinguish from the far more common osteosarcoma.

The cause of fibrosarcoma is largely unknown. It is a rare tumor in comparison to osteosarcoma. This cancer is seen most commonly in older male dogs, except for a certain variety that is seen in the mouths of younger dogs. Most commonly, it effects the bones of the spine, pelvis and skull but can less commonly effect the legs.

What to Watch For

Symptoms of bone cancer in dogs may include:

Diagnosis of Fibrosarcoma of the Bone in Dogs

Treatment of Fibrosarcoma of the Bone in Dogs

Home Care

Your veterinarian will likely prescribe pain medications to assure your dog’s comfort, prior to definitive diagnosis and/or in the aftercare period from surgery.

You should limit activity of your dog to prevent further pain and to prevent what is called a pathologic fracture, which is an abnormal breaking of the bone due to weakening by cancer, prior to definitive therapy. Your pet should not run, jump or play during this time and you should watch him carefully or help him when climbing stairs or getting in and out of the car.

Any unexplained bump, lameness or problems with your pet’s mouth should be promptly evaluated by your veterinarian. Most forms of lameness are likely to be associated with arthritis or injury to ligaments and tendons. Likewise, most problems with your pet’s mouth are related to tooth decay and gum disease rather than cancer. But if your dog is not getting better with rest, anti-inflammatory drugs or treatment of bad teeth, than radiographs of the affected body part should be taken to rule-out bone cancer.

If fibrosarcoma occurs in an area of the body that can be completely removed with surgery, the prognosis can be good for 1 to 2 years or more, as it is a type of cancer that rarely spreads.

In-depth Information on Canine Bone Fibrosarcoma

Fibrosarcoma is an uncommon type of cancer to affect the bone. They arise as masses in the mouth more commonly than in the legs. They are often very difficult to distinguish from the more common bone cancer osteosarcoma when small biopsy samples are evaluated. Understandably, this is an important distinction as treatment and prognosis vary drastically for these two cancers. It often requires a larger sample of the tumor to be submitted for a pathologist to make this determination.

Very rarely a bone cancer could be due to the metastasis (spread) of cancer from a primary cancer elsewhere in your pet. The most common types of cancer that spread to bone are mammary gland cancer, prostate cancer, urinary bladder cancer, multiple myeloma and lymphosarcoma. These cancers tend to have a distinctively different appearance on X-rays that tips off their presence but still require a biopsy to definitively diagnose them. It is important to distinguish this latter group of metastatic cancers to bone, as the approach to treatment is much different and involves finding out where the primary cancer is in the body.

In-depth Information on Diagnosis

Your veterinarian will perform a complete medical history and a thorough physical examination. Medical tests are needed to establish the diagnosis, exclude other diseases, and determine the impact of fibrosarcoma on your dog.

In-depth Information on Therapy

Follow-up Care for Dogs with Bone Fibrosarcoma

Optimal treatment of your dog requires a combination of home and professional veterinary care. Follow-up can be critical, especially if your pet does not rapidly improve. Administer all prescribed medications as directed. Alert your veterinarian if you are experiencing problems treating your dog.

Your veterinarian should prescribe pain medications to assure your dog’s comfort either prior to definitive diagnosis and/or in the aftercare period from surgery as discussed above. This can be through the use of pills or narcotic pain patches placed on the skin that release a constant level of pain medications across the skin.

You should limit activity of your dog to prevent further pain and to prevent a pathologic fracture prior to definitive therapy. Your pet should not run, jump or play during this time and you should watch carefully or give assistance when they are climbing stairs, or getting in and out of the car.