Fibrosarcoma of the Bone in Dogs

 

Fibrosarcoma is a result of the abnormal division of fibroblast cells – the cells that are most prevalent in the connective tissue of the body, and normally this type of tumor originates in the soft tissue. In some rare cases, however, a fibrosarcoma tumor originates in the bone, weakening the structure of the bone, and possibly leading to fractures, and even amputation of the limb. In most cases fibrosarcoma of the bone is benign and non-metastasizing, but there are cases where the tumor is malignant and metastasizes throughout the body, into the organs, lymph nodes and skin.

 

Clinically, fibrosarcoma of the bone is similar to osteosarcoma, a more common form of bone cancer. The main differences are in the make-up of the tumors. Where an osteosarcoma is made up of bone material, a fibrosarcoma is made up of fibrous collagen material. Fibrosarcoma is confirmed when a biopsy of the tumor shows no production of bone material. The rapidly dividing nature of a sarcoma is the real danger, as it invades and threatens the stability of the bone. In general, tumors of the bone are benign, and are frequently misdiagnosed as cysts and muscular problems.

 

Age, breed or gender dispositions have not been determined for this diseased condition.

 

Symptoms and Types

 

There are two main types of fibrosarcoma of the bone:

 

Central fibrosarcomas:

• Appear in the long bones, vertebral column, and mandible

 

Periosteal fibrosarcomas:

• Appear in the skull bones

 

Symptoms

• Loss of motion and inability to walk
• Mass can be palpated (examined by touch) at the affected bone
• Swelling at the site
• Swelling of the face when tumor originates in the skull bones
• Pain when area is touched
• Fractures of the bone without other evidence of trauma

 

Causes

 

The exact cause for fibrosarcoma of the bone is still unknown.

 

Diagnosis

 

You will need to give a thorough history of your dog's health, onset of symptoms, and possible incidents that might have led to this condition, such as any accidents or illnesses, and your dog's regular exercise routine. The more detail you can provide, the better equipped your veterinarian will be to diagnose the condition. Standard laboratory tests include urinalysis, a complete blood count, and a chemical blood profile.

 

The presence of higher than normal white blood cells can indicate that the body is warding off a diseased condition, and the other tests will show whether the organs are functioning well. Often, however, laboratory tests will return as normal. Because of the relative rarity of a fibrosarcoma of the bone, unless an x-ray image is taken it may be diagnosed as a cyst or a swelling in the muscle. Therefore, an x-ray examination will be an important factor in the definite diagnosis. X-rays will also help to diagnose the exact location of the primary tumor, as well as detecting whether there has been metastasis to other parts of body. A computed tomography (CT) scan is another useful diagnostic viewing tool that may help in determining the extent of problem.

 

For a more conclusive diagnosis, a biopsy of the tumor will need to be taken for analysis. A biopsy of the bone is a more invasive procedure than most, but this is the only way to confirm whether a tumor is benign or malignant. Your dog will need to be anesthetized for this procedure.

 

 

 

Treatment

 

The treatment of fibrosarcoma of the bone usually involves an aggressive surgical approach in which removal of the area around the tumor is attempted, or a piece of the affected bone is removed. In some cases, the affected limb will need to be amputated entirely. A tumor that has already metastasized to multiple sites before diagnosis carries a poor prognosis for recovery. Keep in mind that not all fibrosarcomas are alike. The tumor that is affecting your dog may not have metastasizing properties, and excision of the tumor and surrounding tissue may very well resolve the problem. In other more serious cases, there may be a recurrence at the site of the amputation.

 

Living and Management

 

After the initial treatment, a follow up checkup will be planned to regularly monitor for any re-growth of the tumor or metastasis to other areas of the body. You will need to set up a schedule to visit your veterinarian for routine progress checkups. A full recovery will be dependent on the size and location of the tumor.

 

After surgery, or while your dog is being treated for the tumor, you should expect your dog to feel sore. Your veterinarian will give you pain medication for your dog to help minimize discomfort. Use pain medications with caution; one of the most preventable accidents with pets is overdose of medication. Follow all directions carefully. You will need to limit your dog's activity while it heals, setting aside a quiet place for it to rest, away from household activity, children, and other pets. It might be practical to consider cage rest for your dog, to limit its physical activity. Your veterinarian will tell you when it is safe for your dog to take exercise again. Until then, only take your dog for short walks.

 

It is important to monitor your dog's food and water intake while it is recovering. If your dog does not feel up to eating, you may need to use a feeding tube or a high protein liquid supplement so that it is getting all of the nutrition it needs to completely recover. Your veterinarian will show you how to use the feeding tube correctly, and will assist you in setting up a feeding schedule.