Hemangiosarcoma in Cats and Dogs
What are hemangiosarcomas?
Hemangiosarcoma (also known as hemangioendothelioma or angiosarcoma) is a malignant soft tissue sarcoma cancer that
arises out of blood vessels. It may be present as a single tumor or as multiple tumors, and often ruptures and bleeds. It
occurs more frequently in dogs compared to other species and is mostly seen in middle-aged to older animals. German
Shepherds, Golden retrievers, and Labrador retrievers appear to be at higher risk.

How common are hemangiosarcomas in cats and dogs?
Hemangiosarcoma (HSA) represents about 5% of all non-skin malignant cancers in dogs, 2.3-3.6% of skin tumors in dogs,
45-51% of
spleen cancers in dogs and 2% of all cancers in cats. The most common organ that develops
hemangiosarcoma in the dog is the spleen (for more details, please see the
Spleen Hemangiosarcoma section) but other
sites have been reported such as the heart (for more details, please see the
Heart Hemangiosarcoma section), skin, liver,
lung, kidneys, mouth, muscle, bone, bladder, uterus. In the cat, hemangiosarcoma has been reported equally in the skin,
spleen, liver, and intestine, and less frequently in the heart, chest cavity, and nasal cavity. Skin hemangiosarcoma has a
tendency to develop in dog's light-haired or poorly pigmented skin.

What are the symptoms of hemangiosarcomas in cats and dogs?
The symptoms will vary depending on the tumor's location. They can range from nonspecific signs to abdominal swelling to
acute death due to bleeding. Common symptoms for hemangiosarcoma (HSA) of internal organs include sudden weakness
or collapse, but can also be vague such as chronic weakness, lack of appetite or weight loss. Dogs with
hemangiosarcoma typically show signs of exercise intolerance and shortness of breath. More advanced skin
hemangiosarcomas can have a bruised appearance and can, therefore, be mistaken for a bruise.

How is the diagnosis made?
The tests used to diagnose hemangiosarcomas include blood and serum biochemistry tests, blood clotting test, ultrasound
and other
imaging studies if necessary. Blood tests of pets with HSA will often reveal deficiency of red blood cells. As is the
case with all types of cancers, the definitive diagnosis of hemangiosarcoma requires

Does cancer cause pain in pets?
Pain is common in pets with cancer, with some tumors causing more pain than others. In addition to pain caused by the
actual tumors, pets will also experience pain associated with cancer treatments such as surgery, radiation therapy or
chemotherapy. Untreated pain decreases the pet's quality of life, and prolongs recovery from the illness, treatment or
injury. It is, therefore, essential that veterinary teams that are taking care of pets with cancer should also play a vital role in
educating pet owners about recognizing and managing pain in their pets. The best way to manage cancer pain in pets is to
prevent it, a term referred to as preemptive pain management. This strategy anticipates pain ahead of time and
administers pain medication before the pet actually experiences pain, thus ensuring the pet's maximum comfort.

To learn more about which tumors are likely to cause a lot of pain, how to recognize pain in pets with cancer and what
cancer pain management options are available for your pet, please visit the
Cancer Pain Management section.

How important is nutritional support for pets with cancer?
Cancer cachexia (a term referring to progressive severe weight loss) is frequently observed in pets with cancer. Pets with
cancer lose weight partly because of lack of appetite and partly because of cancer-induced altered metabolism. Some of
the causes for decreased appetite are related to the cancer itself (for example, tumors may physically interfere with food
chewing, swallowing, and digestion process) and some may be related to the side effects of cancer treatment (for example,
some chemotherapy drugs cause nausea and vomiting, and radiation therapy can cause mouth inflammation).

Proper nutrition while undergoing cancer treatment is essential to maintain your pet's strength, improve survival times,
quality of life and maximize response to therapy. Adequate nutritional support was shown to decrease the duration of
hospitalization, reduce post-surgery complications and enhance the healing process. Additionally, pets with cancer need to
be fed diets specifically designed to provide maximum benefit and nutritional support for the patient. To learn more, please
visit the
Cancer Nutrition section.

What are the treatment options and prognosis for hemangiosarcomas in cats and dogs?
To learn more about specific treatment options and prognosis of specific hemangiosarcomas, please click on the following
Spleen hemangiosarcoma
Heart hemangiosarcoma

How do I find a qualified veterinary oncologist?
To locate a qualified veterinary oncologist worldwide who can discuss with you appropriate cancer treatment plan for your
pet's cancer condition, please visit the "
Locate a veterinary oncologist" section.  

Are there any clinical trials investigating new treatments for hemangiosarcoma in cats and dogs?
There are several available clinical trials (partially or fully funded by the institutions) investigating new treatments for
spleen hemangiosarcomas in dogs. To learn more about these clinical trials, please visit
Clinical Trials for Spleen
Hemangiosarcoma section.

Additionally, there are several clinical trials available for cats and dogs with any tumor type for which your pet may qualify.
To learn more these trials (which are partially or fully funded by the institutions), please visit the
Dog Clinical Trials (any
tumor type) or Cat Clinical Trials (any tumor type) section.  

To learn more about veterinary clinical trials in general, please visit the
Pet Clinical Trials section.

Additional online resources about hemangiosarcoma in pets:

  • www.veg.uga.edu/vpp/cler/frankhauser/index.php
  • Withrow Stephen J, and David M. Vail. Small Animal Clinical Oncology. St Louis: Saunders Elsevier, 2007.
  • Morrison Wallace B. Cancer in Dogs and Cats: Medical and Surgical Management. Baltimore: Williams&Wilkins, 1998.
© 2007 Pet Cancer Center. ALL RIGHTS RESERVED.
Last updated 2/19/2017
Comprehensive guide to cancer diagnosis and treatment in cats and dogs