Hemangiosarcoma by Anita R. Weidinger, D.V.M. Cancers are named for the cell type that they originate from; therefore, hemangiosarcoma is a malignant cancer that comes from hemangio meaning blood vessels or blood and sarcoma meaning malignant cancer of the supporting structures of the body. This type of cancer tries to build blood vessels in a haphazard fashion which essentially makes blood blisters and disrupts normal organ function. These blood blisters also rupture easily causing bleeding from the cancer sites. This is a very common form of cancer in dogs and most often affects older, large breed dogs. More male dogs than female dogs are affected and the two most represented breeds are the golden retriever and the german shepherd. This type of cancer could be called the silent killer since it usually doesn't show itself until it is advanced. If these dogs show any early signs, they include a decreased appetite, weight loss, weakness, pale gums, vomiting, and possibly abdominal distention. Most of the time these dogs don't show any signs until the cancer has really taken over and they are bleeding from the blood blisters. The most common organs affected with hemangiosarcoma are the heart and the spleen, both very vascular organs. If the spleen is affected, the spleen enlarges with these lumpy blood blisters which bleed easily. Usually by the time this is diagnosed, the cancer has spread to the liver and other sites in the abdomen and possibly to the chest. Sometimes early in the growth of the cancer, the enlarged spleen can be felt and diagnosed before much bleeding has occurred. When the heart is affected, bleeding occurs into the pericardium (the sac around the heart). This creates so much pressure on the heart that it can't work properly. If the blood is not drained off quickly, the heart stops. As you can understand, this is a very difficult cancer to diagnose at a time when surgical removal of the cancer will really help the patient long term. Fifty percent of these patients have already had the cancer spread to the rest of the bodies at the time they are diagnosed. Besides the heart and the spleen, this cancer can be in the mouth and in the bone. It can spread secondarily to the liver, kidney, other areas in the abdomen, and to the lungs. Unfortunately, the most common way these patients can be presented to a veterinarian is when they collapse either from acute anemia or from heart failure. That's why it's known as the silent killer.   Return to Support Corner