More than half of dogs over 10 years of age will develop cancer, and many of these are so severe as to be life ending. Cancer is a mass of tissue that grows when cells divide abnormally fast. This is typically from an abnormal genetic copy of a normally dividing cell. Therefore, any cell type can undergo this process and develop a ìcancerî of that tissue. When you hear a cancerís name, very often it is called by the tissue from which it originates. In past columns, Iíve discussed Lymphoma or a cancer of the lymphatic tissue and osteosarcoma or a cancer of boney tissue.This month, the topic is on another top 10 cancers in dogs ó the hemangiosarcoma. Hemangio is the medical prefix referring to blood vessels. A hemangioma or a ìstrawberry markî is sometimes seen in newborn children. This is a benign vascular tumor derived from blood vessel cells. Therefore, when you hear Hemangio you can think of blood vessels. When these cells develop a cancerous growth that divide rapidly and invade other tissues, it can become one of the most feared cancers in the dog, or a hemangiosarcoma. The median survival time after a diagnosis is made is counted in days to weeks.These cancers are most often seen either as a skin tumor, or a large growth on the dogís spleen or at the base of their heart. Risk factors include heredity as certain breeds have this type of cancer more than others; and then there is ultraviolet light exposure such as long-term exposure in lightly pigmented short-haired breeds; and the genetic predisposition for cancer development. Hemangiosarcoma usually occurs in middle-aged and geriatric dogs. Breeds that seem to have more of this type of cancer are golden retrievers, German shepherds, Labrador retrievers, English setters, boxers and Doberman pinschers.This cancer can be seen early as a very simple little ìbumpî on the skin, and then perhaps grow into a more concerning skin lump or lesion. They can become ulcerated and bleed. About 33 percent of these tumors will spread to internal organs, so early identification and removal are key.The visceral (or internal organ) form can quickly become life threatening, and it is the most common presentation of this aggressive cancer. The most affected organs are the spleen, heart and liver. Visceral hemangiosarcoma is often life-threatening since tumors tend to rupture and bleed profusely.What should you do?Any skin mass larger than a pea (1 cm) and/or any that has been present for more than one month should be evaluated by a veterinarian. The doctor should aspirate some cells from the mass(es) to determine the type of growth. No one ó not even a veterinarian ó can simply look at a skin mass and know what it is.Patients with visceral hemangiosarcoma often donít have any clinical signs until a tumor is very large in the abdomen or in the chest. It can rupture and cause serious internal bleeding. Depending on the location and severity of the bleeding, these dogs may be depressed, refuse to walk or play, develop pale (or white) gums, have trouble breathing, collapse and have a distended abdomen.Is there treatment?This all depends on the location of the tumor and how long it has been growing. When identified early, surgical removal of the dermal type can be curative. The reported median survival time (MST) for the dermal form is 780 days. The MST for the subcutaneous hemangiosarcoma is 172-307 days; and, if the tumor develops on the spleen or on the heart, the survival time is frankly only weeks to days after a diagnosis is made.Recently, some novel interventions have been reported to afford a survival benefit in dogs with specific forms of hemangiosarcoma. Antibody therapy is one of the new methods of fighting cancer in general. Researchers are looking into the treatment with antibodies to inhibit the activity of vascular endothelial growth factor or VEGF. This antibody regulates the formation of new blood vessels so it may be used to regulate the uncontrolled growth of these cells. In addition, there are immune therapies and some leading edge chemotherapies that have shown real promise.In my practice, we see this cancer at the end stage and often these dogs are very pale as they are hemorrhaging from the highly vascular tumor. It is sad to see these dogs dying from a cancer that is simply robbing them of life. I surely hope we will one day have a genetic or immune therapy that will save the lives of these dogs ó and even their human owners.
Dr. Jim Humphries is a veterinarian in Colorado Springs and serves as a visiting professor at the College of Veterinary Medicine at Texas A&M University. His specialty practice provides hospice and end-of-life care for pets. He lives in Falcon with his wife, horses and Great Danes. www.HomeWithDignity.com
