Hemangiosarcoma (HSA) in Dogs


Overview of Canine Hemangiosarcoma 

Hemangiosarcoma is a malignant cancer of the cells that form blood vessels. Because these tumors start in blood vessels, they are frequently filled with blood. Consequently, when a blood-filled tumor ruptures, it can cause problems with internal or external bleeding.  In dogs, hemangiosarcoma is considered to be a very aggressive tumor and can spread rapidly to other organs. Hemangiosarcoma is commonly abbreviated as “HSA”.

Hemangiosarcoma is more common in dogs than in cats. It usually occurs in middle-aged to older dogs 9 to 11 years of age, and German shepherds appear to be predisposed to developing this cancer.

The most common primary location of this cancer in dogs is the spleen. Other primary locations include the heart, liver, skin, and bone; however, it can start in any location where blood vessels are present. These tumors usually spread to the lungs, liver, spleen and heart.

Signs of this disease are usually the result of the tumor rupturing, which causes bleeding. This may occur without any warning, and the symptoms will depend upon where the tumor is located.

  • When the tumor is located in the spleen or liver, the signs are usually due to rupture of the tumor and subsequent bleeding into the abdomen. This causes anemia, weakness and if the bleeding is severe, collapse. The gums may appear to be pale or white. In relatively few animals the diagnosis is made before the tumor ruptures.
  • When this type of tumor occurs in the heart, it can cause symptoms, such as weakness, collapse, difficulty breathing, exercise intolerance and fluid build-up in the abdomen. This is usually due to the development of fluid around the heart, called pericardial effusion. A thin sack, called the pericardium, normally surrounds the heart. In pericardial effusion the sack fills up with fluid and prevents the heart from beating effectively. With hemangiosarcoma, the pericardium fills up with blood due to rupture of the tumor.
  • When the tumor occurs in the skin, a mass or lump can usually be felt in or under the skin. The mass may become ulcerated and bleed. When the tumor occurs in a bone, it can cause pain and discomfort. In some locations, such as a rib, the tumor can be felt as a firm swelling in the bone.
  • What to Watch For

    Signs of hemangiosarcoma in dogs may include:

  • Anemia, weakness and collapse
  • Pale or white gums
  • Difficulty breathing
  • Exercise intolerance
  • Fluid build-up of the abdomen
  • Mass or lump under the skin
  • Swelling in the bone
  • Pain in the bones

    Diagnosis of Hemangiosarcoma (HSA) in Dogs

    Diagnostic tests that may be needed to recognize hemangiosarcoma and to direct treatment include:

  • Complete blood count (CBC) including platelet numbers
  • Clotting tests
  • Serum chemistry panel and urinalysis
  • Abdominal radiographs (X-rays) and/or ultrasound
  • Abdominal tap
  • Chest X-rays
  • Ultrasound of the heart
  • Electrocardiogram (EKG)
  • Pericardial tap
  • Biopsy
  • Treatment of Hemangiosarcoma (HSA) in Dogs

    The treatment and prognosis depends upon the location of the tumor. When the tumor occurs in an internal organ such as the spleen or heart, the chances of long-term survival are poor. Treatment is more successful when this cancer occurs in the skin. Exposure to the sun may play a role in the development of this type of skin cancer. Dogs with poorly-pigmented skin and sparse hair coats, such as the whippet, saluki, bloodhound and English pointer, are more likely to develop this form of hemangiosarcoma. There is no known cause of hemangiosarcoma in other locations. In humans, exposure to certain chemicals such as vinyl chloride has been implicated as a cause.

    Treatment for hemangiosarcoma in dogs may include the following:

  • Stabilization
  • Intravenous fluids
  • Blood transfusion
  • Pericardial tap
  • Surgery
  • Chemotherapy
  • Radiation therapy
  • Home Care and Prevention

    Seek veterinary attention promptly if your dog develops pale gums, signs of weakness or collapse. Have any new lumps on your pet evaluated by your veterinarian.

    Minimize your dog’s exposure to the sun, especially dogs that are poorly pigmented and have a sparse hair coat.

    In-depth Information on Hemangiosarcoma (HSA) in Dogs

    Hemangiosarcoma must be differentiated from other diseases that might cause similar clinical signs. For example, diseases of the heart such as an irregular heart rhythm can cause pets to show signs of weakness or collapse. There are several other malignant tumors that can appear as a mass in the spleen including:

  • Fibrosarcomas
  • Malignant fibrous histiocytomas
  • Undifferentiated sarcomas
  • Osteosarcomas

    These tumors can also rupture leading to bleeding from the spleen and the development of anemia. Some systemic cancers may involve the spleen either in addition to other sites or as the primary site. The two most common cancers where this occurs are lymphosarcoma and mast cell tumor. Although not common, other tumors can spread or metastasize to the spleen causing similar signs as hemangiosarcoma.

    Other diseases that can cause similar signs include:

  • Hemangioma, which is the benign counterpart of hemangiosarcoma. This tumor can cause the same clinical signs as hemangiosarcoma but does not spread to other areas of the body. This tumor type is rare.
  • Splenic torsion. The spleen can become twisted, which can lead to enlargement of the spleen and possible rupture.
  • Hematoma of the spleen. A blood clot can form in the spleen causing anemia and/or a mass in the spleen. Although generally there is a history of trauma, this can also occur without any known injury.
  • Aortic body tumor, which is the most common other tumor of the heart. This can occur in the same location as hemangiosarcoma and cause similar signs. Ultrasound of the heart may not be able to differentiate between hemangiosarcoma and other tumor types such as an aortic body tumor.
  • Idiopathic pericardial effusion. This condition in dogs causes fluid build-up around the heart. The cause is unknown but it can be managed by periodic removal of the fluid or surgery. Other types of tumors can also cause pericardial effusion.
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