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Hemangiosarcoma: Aggressive Cancer in Dogs

Posted November 23, 2015 in Dog Diseases & Conditions A-Z

AJ Debiasse, a technician in Stroudsburg, PA, contributed to this article.

Hemangiosarcoma is an aggressive type of cancer that can affect organs where blood vessels are present. Unfortunately, this means that any part of your pet’s body can be affected, since blood vessels are everywhere.

Signs of hemangiosarcoma in dogs
Even though hemangiosarcoma can occasionally develop in the skin, it’s most common in the internal organs, such as the spleen or the liver. Because of this, most of our pets often don't show signs until their condition is advanced or sometimes critical. Signs usually occur after a tumor has developed in an internal organ and has ruptured, causing internal bleeding. The loss of blood or anemia (a low red blood cell count) causes:

Depending on the situation, it can also cause extra heart beats.

Is my dog at risk for hemangiosarcoma?
All pets can be affected by hemangiosarcoma, but large breed dogs have the highest occurrence. They tend to be adults or seniors. The cause is unknown, but may have a genetic origin.
Sad Woman with Sad Dog
Diagnosing hemangiosarcoma
The diagnosis of hemangiosarcoma usually starts with a physical exam. The skin form can usually be felt by palpating (or feeling) a lump in the skin. In the case of a mass in the belly, your veterinarian may notice pale gums, swelling of the belly and may be able to obtain a sample from the abdomen. Chest X-rays are recommended to help assess the severity and determine if there is spreading to the lungs. Abdominal ultrasound can be helpful. Full blood work is also recommended.

Treating hemangiosarcoma
Depending on the location, the tumor, the entire organ (e.g. the spleen) or part of the organ (e.g. part of the liver) can be removed. Postop chemotherapy is often recommended to increase survival time.

Removal of hemangiosarcoma is a major surgery, so your dog will need to rest strictly. An Elizabethan collar (plastic cone) will prevent your dog from injuring the incision. Antibiotics and pain medications are usually administered for at least 7 days. A diet change may be recommended.

It is extremely rare to cure hemangiosarcoma. The average survival time with surgery alone, if internal organs are involved, is 3 to 6 months. If the spleen is involved and it has not ruptured, the outcome is better. If at the time of surgery, there is no visible metastasis ( spreading of cancer) and the patient follows up with chemotherapy, we hope for a mean survival time of one year.

Nobody will force you to choose chemo, but you need to be aware that without it, the survival time is greatly decreased.

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Dr. Phil Zeltzman is a board-certified veterinary surgeon and author. His traveling practice takes him all over Eastern Pennsylvania and Western New Jersey. You can visit his website at, and follow him at