Hemangiosarcoma is a type of cancer that begins in the cells that line blood vessels. Tumors usually develop in the spleen, heart, or liver, although they can also been found in the skin, bone, kidney, brain, and other locations. Hemangiosarcoma is almost always malignant, and tends to develop slowly, but spread rapidly, so that clinical signs are often not noticeable until the tumors have metastasized and/or ruptured, causing acute shock and collapse.
Causes of Hemangiosarcoma
Dermal hemangiosarcoma (tumors of the skin) are often caused by sun exposure. The other forms of hemangiosarcoma do not have a known cause, although there seems to be a genetic link in many breeds.
Hemangiosarcoma is more common in dogs than in other species. Studies have already shown that there are certain breeds that are at higher risk for developing hemangiosarcoma. However, it can affect any dog, purebred or mixed breed alike. Hemangiosarcoma is currently a fatal disease.
Symptoms of Hemangiosarcoma
Clinical signs of hemangiosarcoma include loss of appetite, arrhythmias, weight loss, weakness, lethargy, collapse, pale mucous membranes, and/or sudden death. The most severe signs are caused from acute blood loss. These can vary from an enlarged abdomen due to hemorrhage to bleeding into the lungs or the pleural space (outside the lungs) that compromises breathing, to bleeding into the heart sac that prevents the heart from beating normally. Metastasis is most commonly to the liver, stomach lining, lungs, or brain.
There is presently no readily available, effective test for early diagnosis of hemangiosarcoma. Careful analysis of blood samples by experienced pathologists may hint at the presence of chronic hemorrhage and blood vessel abnormalities that are suggestive of hemangiosarcoma. However, this method is neither sensitive nor specific to confirm the diagnosis. Non-invasive imaging methods are useful aids to diagnose the disease. In particular, ultrasound is moderately specific, but it is not sensitive, and the tumor must be large enough to be grossly visible. In addition, biopsies are required for confirmation of imaging results. Repeated biopsies of tissues where the tumors may arise (without other evidence for the presence of a tumor) are of little use to provide early diagnosis, and considering the fact that there is some risk to these procedures, such an approach is practically and ethically unacceptable.
The first line of treatment, whenever possible, is removal of the tumor with the affected organ, such as with a splenectomy. The standard of care includes chemotherapy as a follow-up to surgery. Unfortunately, visceral hemangiosarcoma (the type that occurs in organs other than the skin) is most often fatal even with treatment, usually within weeks to months. However, approximately 10% to 15% of dogs have excellent response to treatment with durable remission and extended survival. We do not know why some tumors respond so well while most fail. Hemangiosarcomas of the skin may be successfully treated if the tumor hasn't metastasized to other internal organs.
Care for Dogs with Hemangiosarcoma
If tumors are found early, life can be prolonged. Additionally, treatment for the bleeding disorders and aggressive supportive care also prolong the life of patients with hemangiosarcoma.
The AKC Canine Health Foundation and Hemangiosarcoma
Fifteen grants to study hemangiosarcoma have been funded by CHF to the tune of $1.3 million. These studies are looking for genetic predisposition, advanced methods of diagnosis, and treatment.