WHAT IS CANINE HEMANGIOSARCOMA?
Canine hemangiosarcoma or HSA, is a cancer that develops in the cells that form blood vessels (endothelial cells). Interestingly, dogs are the species that are the most diagnosed with this type of cancer. It is estimated that as many as two million dogs get this cancer. Most will unfortunately die from HSA, as the disease is usually incurable. There is one form of HSA that is generally less aggressive, and that is cutaneous melanoma. The cause has been attributed to exposure to the sun, and is generally treatable with surgery.
Dogs are usually middle-aged and older when they develop the disease, and some breeds are known to be predisposed to HSA. German Shepherds, Golden Retrievers, Portuguese Water Dogs, and Skye Terriers are four of them. That being said, any breed and sex can develop HSA.
THE CAUSES OF CANINE HEMANGIOSARCOMA
Much more research is needed for this type of canine cancer. Sun exposure and genetics appear to result in an increased risk of developing this tumor. The exact cause is unknown.
SYMPTOMS OF CANINE HEMANGIOSARCOMA
The biggest problem with this disease is that the symptoms can mimic a benign tumor such as a hematoma, or an inability to clot blood, such as seen when a dog ingests rat poison. Quite often you do not even know the tumors are present until a bigger problem presents itself, such as blood loss from a ruptured spleen or liver. They are frequently painless as well, which makes detection of an issue difficult.
Clinical signs that the family might notice include pale gums, rapid breathing, an acute weight gain due to fluid, often blood, in the abdomen, extreme fatigue or lethargy, and eventual collapse. These tumors can grow and then rupture. Since the tumors develop in the cells that form blood vessels, the ruptures cause acute bleeding. That brings on the symptoms mentioned above here. While blood is not seen outside of the dogs’ body, a sick dog is losing blood internally.
DETECTION AND STAGING
The staging generally consist of a minimum of blood work, three-view chest X-rays, abdominal and heart ultrasound, and urinalysis. There may be other tests ordered, or the animal may arrive in a state of shock due to internal bleeding, necessitating immediate supportive care prior to surgery; IV fluids, pressure wraps to help stop bleeding, and blood pressure checks, for example.
Surgery is usually recommended, mainly because there is really no other way to see for sure if a mass is malignant or not. It is also the only way to stop a patients internal bleeding. This not only can save the dogs’ life at this particular time, but a tissue sample can be taken to confirm a diagnosis of HSA.
Hemagiosarcomas can occur anywhere in the body and may present as a mass on sites such as the spleen, liver, muscle, heart, under the skin, on the tongue and on the skin. Surgery is the single most effective treatment for patients with hemangiosarcomas. Unfortunately, for most patients, it is not possible to determine the cause of the bleeding until the mass is evaluated by a pathologist after it was removed. For example, for dogs with a mass on the spleen, 2/3rds of them are malignant, one third is not. Of the two thirds of the dogs with a malignant splenic mass, two thirds of them have hemangiosarcoma. To make things more difficult, not all hemangiosarcomas are the same; some are low grade with a more favorable prognosis, whereas others are intermediate and high grade hemangiosarcomas. The high grade tumors are generally quite aggressive.
Thus, even though surgery may be essential to save the dogs’ life in a crisis, it is rarely the only answer. Since hemangiosarcoma is a very aggressive disease, the life expectancy after surgery may be a few weeks to a few months. Chemotherapy is generally recommended after surgery, since this cancer metastasizes early and quickly. Doxorubicin based chemotherapy is used most commonly.
The average survival time for dogs with a malignant hemangiosarcoma after both surgery and chemotherapy may be only six to eight months. A great deal of research is underway to find new treatments for this very aggressive disease.