Fibrosarcoma in Cats and Dogs Causes, Symptoms, and Treatment Options for Fibrosarcoma

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Fibrosarcoma is a form of cancer that is most commonly found in the skin and soft tissue of dogs and cats. Find out more here in order to better understand this particular form of cancer and what options are available.

Fibrosarcoma ... It even sounds unpleasant, doesn’t it? With the root ‘sarcoma’ you know it’s a cancer, but what exactly is fibrosarcoma?

Fibrosarcoma is a cancer that appears in the skin and soft connective tissues of both cats and dogs. Fibrosarcoma in cats is often found between the shoulder blades, on the back of the neck, and on the chest. Fibrosarcoma in dogs is often found in the mouth, particularly the jaw, and on the limbs. In rare cases though, the cancer can be found in the bones of both animals.

The tumors vary in growth rate between cats and dogs and from breed to breed. Prognosis varies as well depending on the location and size of the tumor, as well as the age and overall health of the animal.

Causes of Fibrosarcoma

While we know that fibrosarcoma is a cancer that originates in the soft tissue, no one knows for sure what exactly causes the fibroblast cells of this tissue to divide so abnormally and quickly. Here are the theories.

In cats, some researchers have linked fibrosarcoma to recombinant forms of the feline leukemia virus, especially in young cats, as well as cats older than 5 years of age who exhibit multiple tumors. Other researchers have turned their attention to vaccinations, stressing that the tumors commonly appear at the injection site -- the shoulders and neck. However, traces of virus particles from the vaccinations have not been found in the tumors.

A subtype of fibrosarcoma, feline sarcoid, is thought to be caused by a papilloma virus, which is responsible for wart growth.

In dogs, the theories are few and far between, but researchers have found fibrosarcoma to be more common in larger breeds of dog, especially those who are 10 years of age and older. However, serious cases with poor prognosis have been seen in dogs younger than 1 year.

Fibrosarcoma Symptoms

The most common and apparent symptom of fibrosarcoma in cats and dogs is a lump, which at times may be accompanied by ulceration and bleeding. Other common symptoms include swelling of the affected area and pain when the area is touched. You may find that your pet becomes less social, refuses to be touched, and experiences a loss of appetite due to the resulting pain. If the tumor appears on the legs, related symptoms include loss of motion and an inability to walk.

When in the bone, fractures may occur even if there has not been an incident of physical trauma.

Fibrosarcoma Diagnosis

Fibrosarcoma in both cats and dogs is commonly spotted during a physical examination. If your veterinarian comes across a lump he or she believes to be a tumor, they will review your pet’s health history and ask questions regarding onset of symptoms, as well as any out of the ordinary incidents, such as accidents or illnesses. They’ll then call for laboratory tests including a urinalysis and blood work. If symptoms point to possible fibrosarcoma of the bone, x-rays are administered and occasionally a CT scan. A biopsy of the tumor is then taken to determine if it is benign or malignant.

Fibrosarcoma Treatments

Since fibrosarcoma does not respond well to radiotherapy or chemotherapy, surgical removal of a tumor is often recommended. During removal, the veterinarian typically extracts excess tissue around the tumor to be certain it is completely removed.

Until the procedure is performed you will need to focus on everyday treatment of the existing tumor. This includes preventing your pet from rubbing, scratching, licking or biting the tumor, as well as keeping the area clean, especially if the tumor has become ulcerated.

Post surgery, your pet will need a lot of rest and some special care:

  • If possible, set up a special spot in a quiet, temperature-controlled area of your home.
  • Your pet will also be in a lot of discomfort, so pain medication may be prescribed.
  • Be sure to follow all directions to avoid a possible overdose.
  • The resulting pain may also affect your pet’s eating habits, causing them to eat less.
  • Monitoring their water and food intake can help avoid dehydration or malnourishment during the healing process.

If your pet isn’t eating, the vet may recommend specific foods and nutritional supplements.
You’ll want to keep your pet from rubbing, scratching, licking, or biting the incision site.
Of course, keep the area clean to prevent infection.

If the fibrosarcoma is found within the bone, the surgical approach is typically more aggressive, and removing part of or the entire bone may be required. Post-surgery treatment will vary.

Follow up visits to the vet to regularly monitor for any re-growth of the tumor or spread of the fibrosarcoma are necessary, but the good news is a full recovery is possible. 

More on Cancer

Bone Cancer in Dogs and Cats
3 Ways to Save on Dog Chemo and Cancer Drugs
Nutrition for Dealing with Cancer in Dogs and Cats

This information is for informational purposes only and is not meant as a substitute for the professional advice of, or diagnosis or treatment by, your veterinarian with respect to your pet. It has, however, been verified by a licensed veterinarian for accuracy.

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