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Canine hemangiosarcoma is a highly malignant, rapidly spreading cancer of the cells that line the blood vessels. As the cancer grows, because it involves the blood vessels, it disrupts blood supply to involved tissue and causes bleeding. Bleeding can be insidious (without symptoms) and chronic for a period of time, or can be sudden and massive resulting in rapid death. Any age or breed of dog can have hemangiosarcoma but it is most common in middle age or older dogs and in large breeds. It is, interestingly, extremely rare in humans and in cats.
There are three basic forms of hemangiosarcoma and signs and symptoms are related to the form:
Hemangiosarcoma grows rapidly but is painless as it grows and spreads. Eventually there is internal bleeding which can be intermittent and cause brief episodes of pain and/or swelling, and sometimes anemia with paleness of mucous membranes. The dog may recover from these for periods of time. During these times, if the blood loss is great enough, the dog may show signs of fatigue or weakness. And during these times, even though the dog may seem to improve, the cancer is aggressively spreading and metastasizing to other areas of the body. There may be disruptions of organ function such as abnormal heart rhythms, loss of appetite, weight loss, or clotting disorders. Eventually there is rupture of a large tumor, resulting in severe hemorrhage, collapse, shock and even death. By the time of diagnosis, the cancer has almost always spread to the point of being incurable.
The cause of canine hemangiosarcoma is not known but is believed to be, at least in part, genetic because it is so common in dogs and in certain breeds of dog, but not in other animals. Environmental factors also play a role.
Specific risk factors are not known. Sun exposure can contribute to the development of dermal hemangiosarcoma in light colored dogs with thin coats. Studies are underway to attempt to identify risk factors in high risk breeds.
Diagnosis is difficult and often occurs too late. Examination of a dog may show signs of anemia or fluid collection in the abdomen. Your vet will most likely perform routine lab tests and tests to look for abnormal clotting, and may aspirate fluid from the abdomen to see if there is blood. X-rays may be helpful in determining the extent of involvement, and ultrasound may be useful to determine heart and/or spleen involvement. Biopsies may be helpful and may provide a definitive diagnosis, but are also potentially dangerous as they may precipitate bleeding.
Note: Treatment of animals should only be performed by a licensed veterinarian. Veterinarians should consult the current literature and current pharmacological formularies before initiating any treatment protocol.
Treatment depends on the location of the tumor. Dermal tumors are most successfully treated as they often can be completely removed through surgery and treated with radiation therapy. Visceral involvement is much more difficult to treat and is rarely curative because of the high rate of metastasis. Surgery and chemotherapy are used but typically extend life only a few months at best.
Hemangiosarcoma. Modiano Lab at the University of Minnesota
Hemangiosarcoma at Wikipedia
Hemangiosarcoma at caninecancer.com