Hemangiosarcoma in Dogs
What is Hemangiosarcoma?
Hemangiosarcoma is the most common primary tumor of the spleen in dogs. Less commonly it originates in the heart or subcutaneous tissues. Hemangiosarcoma leads to the formation of abnormal blood vessels which can rupture and bleed. It also commonly spreads to other places in the body (called metastasis).
Diagnostic tests are recommended to determine which sites in the body are involved. These tests include:
- Complete blood count (CBC)
- Serum biochemistry panel
- Urinalysis (U/A)
- Thoracic radiographs
- Abdominal sonogram
- Cardiac evaluation (echocardiogram)
Treatment of hemangiosarcoma is aimed at both removing the primary tumor with surgery and using systemic medication (chemotherapy) in an effort to delay or prevent metastasis. Doxorubicin is the drug of choice. It is given at 3-week intervals for a total of 4-6 treatments. There are also reports of a combination protocol consisting of vincristine + doxorubicin + cyclophosphamide (VAC). There is a biologic rationale for combination therapy over single-agent therapy, although the benefit of VAC over doxorubicin alone remains unclear for hemangiosarcoma (reported studies have included different populations of dogs, for example). Regardless, we recommend that the initial treatment be given with doxorubicin alone and if this is well tolerated, then consideration be given to adding the other two drugs. Also, due to the potential for cardiotoxicity with doxorubicin, we recommend follow-up cardiac evaluation, consisting of an echocardiogram and ECG, prior to the 4th treatment.
Chemotherapy drugs work by targeting fast-growing cells and cancer cells divide faster and abnormally compared to normal cells. Because of this, chemotherapy preferentially destroys cancer and spares normal tissues. There is the potential for some normal tissues with rapid growth rates (intestinal lining, bone marrow, hair cells) to be transiently damaged by chemotherapy. However, our goal in treating cancer in animals is quality of life, so the dosages are lower than those used in people, and we do not normally see significant toxicity with chemotherapy. There is always some risk when a drug is given for the first time, and the oncologist will discuss what types of side effects may develop and what you should watch for. If the pet has no problems the first time they receive a drug, they should have no problems with subsequent treatments of that drug. If the pet experiences any side effects, we address them as needed and lower the dosage of the causative drug for future treatments to prevent recurrent problems.
While the quality of life for dogs following surgery is generally very good, it is unfortunately not of long duration. Survival times following surgery alone for splenic hemangiosarcoma are approximately 2-3 months. With the addition of chemotherapy, survival times extend to approximately 5-7 months.
Following completion of chemotherapy, or if chemotherapy is not pursued, metronomic therapy may be considered. Metronomic chemotherapy involves the administration of chronic oral low-dose chemotherapy (cyclophosphamide) in conjunction with other medications (carprofen or deracoxib and doxycycline). It is believed that this treatment approach may inhibit angiogenesis (new blood vessel growth) and thereby inhibit tumor growth.
- Hammer AS, Couto CG, Filppi J, et.al. Efficacy and toxicity of VAC chemotherapy (vincristine, doxorubicin, and cyclophosphamide) in dogs with hemangiosarcoma. J Vet Intern Med ;1991;5:160-166.
- Sorenmo KU, Jeglum KA, Helfand SC. Chemotherapy of canine hemangiosarcoma with doxorubicin and cyclophosphamide. J Vet Intern Med 1993;7:370-376.
- Ogilvie GK, Powers BE, Mallinckrodt CH, et.al. Surgery and doxorubicin in dogs with hemangiosarcoma. J Vet Intern Med 1996;10:379-384.