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Hemangiosarcoma of the Skin in Dogs

A hemangiosarcoma of the skin is a malignant tumor which arises from the endothelial cells. The endothelial cells make up the layer of cells collectively referred to as the endothelium, which lines the inner surface of blood vessels, including, but not limited to, the veins, arteries, and intestines. These cells line the entire circulatory system, and are responsible for the smooth flow of blood within the lumen (interior space) of all of the body's inner structures and tubular spaces.

Because this type of sarcoma grows from the blood cells, the growths themselves are filled with blood. This accounts for the dark blue or red coloring of the mass. If the growth is limited to the outer layer of skin, where it can be removed entirely, the prognosis may be guardedly optimistic, but because of the highly metastatic nature of this cancer, it is sometimes found to reach deep into the tissue, or to have arisen from a deeper, visceral location. In the latter case, the outcome is often fatal.

This type of cancer accounts for 14 percent of all hemangiosarcomas in dogs. At heightened risk are boxers, pit bulls, golden retrievers, German shepherds, and dogs between the ages of four and 15 years old.

Symptoms and Types

These masses are most commonly present on the dog’s hind limbs, prepuce, and ventral abdomen, but may appear at any place on the body. The tumors may also change in size due to bleeding inside the growth. The following are symptoms related to hermangiosarcoma in dogs:

• Solitary mass or multiple masses on the skin
• Nodules on skin are raised, firm, and dark
• Nodules are usually not ulcerative
• In subcutaneous tissue, masses are firm but soft, and fluctuate underneath
• Bruising appearance may be present on these masses

Causes

Although the cause of hemangiosarcoma of the skin is not known, it is known that particular breeds are at higher risk than others. These breeds include boxers, pit bulls, golden retrievers, German shepherds, English setters, and whippets, leading to the assumption that there is some basis in genetic predisposition. Of course, any breed can be affected, and at any age. Excessive exposure to sun, especially in light colored and short coated dogs, is also thought to predispose some dogs to this cancer.

Diagnosis

Your veterinarian will perform a thorough physical exam on your dog, taking into account the background history of symptoms and possible factors that might have led to this condition. You will need to give a thorough history of your dog's health and onset of symptoms, including any details you have about your dog's breed and familial background, the types of activities your dog takes part in, and any physical or behavioral changes that might have taken place recently.

Routine laboratory tests will include a chemical blood profile and complete blood count. The results of these tests are usually normal but may show an abnormally low number of platelets (cells involved in blood clotting). Abdominal and thoracic X-rays will be taken to determine how invasive the hemangiosarcoma is, whether there is metastasis in the lungs or any other internal organs. In some cases, the tumor may even reach to the bone. Computer tomography (CT) scan and magnetic resonance imaging (MRI) can also be used to view the extent of the disease and in planning the surgery.

A skin biopsy remains the method of choice for confirmation of diagnosis. Your veterinarian will take a sample of tissue from the mass to have it microscopically examined by a veterinary oncologist.