Hemangiosarcoma is an aggressive cancer that arises from the blood vessels. The cancer can occur anywhere in the body, but there are several locations that are more common. Early and aggressive treatment can lengthen the dog's life, but this cancer is often metastatic and complete remission is rare.

Which dogs are at risk for developing hemangiosarcomas?

Hemangiosarcomas can occur in any dog regardless of breed, age, or sex. Hemangiosarcomas are rare in the cat and human. There are several breeds of dogs that seem to be at a greater risk for hemangiosarcoma and they include German Shepherds, Golden Retrievers, Boxers, and English Setters.

We do not currently understand why dogs develop hemangiosarcomas. Because of the increased incidence in several breeds, a genetic link appears to be one of several likely causes. Hemangiosarcoma is rarely found in humans, so less research has been done, and the amount of information about the cause of this tumor is somewhat limited.

What are the symptoms of hemangiosarcoma?

Hemangiosarcomas can occur anywhere on or in the body, but primarily are present in the spleen, liver, heart, and skin. The skin form of hemangiosarcoma has a better prognosis and recovery rate than the internal forms. The skin form is occasionally present in cats and can sometimes be associated with sun damage on light-skinned/haired animals. The internal form is usually diagnosed by the palpation of a large mass in the abdomen or with symptoms of sudden blood loss. The sudden blood loss results from the rupture of the fragile tumor and a resulting loss of blood into the abdomen. The symptoms would include weakness or collapse and pale mucous membranes. Occasionally, dogs will have symptoms of chronic blood loss, which include pale gums, slow capillary refill time (CRT), irregular heart rate, and generalized weakness.

How is hemangiosarcoma diagnosed?

Once a tumor is suspected, abdominal and chest x-rays are often performed to determine the extent of organ involvement and whether or not metastasis is present. Hemangiosarcoma is an aggressive tumor and metastases are often present at the time of initial diagnosis. A biopsy or positive identification of a removed tumor by a veterinary pathologist is usually recommended.

What is the treatment for hemangiosarcoma?

Hemangiosarcoma is primarily treated with a combination of surgery and chemotherapy. Surgical removal alone is often not very rewarding. Because of the high risk of metastasis, the average survival time without chemotherapy is one to two months, with less than 10% of the dogs living a year. With surgical removal and accompanying chemotherapy, the average survival time increases to 5 to 7 months. However, 90% of these dogs still do not survive more than a year after initial treatment. Success rates can improve depending on location and early intervention.

Skin-based hemangiosarcomas appear less likely to be metastatic when initially diagnosed and treatment is more often successful. Surgical removal of the skin-based tumors can be curative, however, chemotherapy is often recommended in addition to surgery. Because of the aggressive nature of hemangiosarcomas and the rapidly changing chemotherapy drugs, I recommend that all owners of dogs with hemangiosarcomas seek out treatment or advice from a veterinary oncologist.

Conclusion

In summary, hemangiosarcoma is a somewhat common tumor in dogs. It can be found in any dog, but has some definite breed predilections. Most of the tumors are metastatic and aggressive and have a guarded outcome. With early detection and treatment with surgery and chemotherapy, survival times and quality of life can be improved.