Hemangiosarcoma: a (usually) silent and deadly canine cancer

November is Pet Cancer Awareness Month. Among the deadliest canine cancers is hemangiosarcoma, or cancer of the blood vessels. Hemangiosarcoma can present as skin cancer, which can be successfully treated if caught early, or as cancer of the internal organs, particularly the spleen or heart. The prognosis for splenic or cardiac hemangiosarcoma is extremely poor, even with aggressive treatment, as often the first sign of any problem is when the tumor ruptures and causes massive internal bleeding. An additional complication arises from the fact that since it is a cancer of the blood vessels, the cancer cells have generally spread to other areas of the body at the time of diagnosis. As a result, the median survival time for internal tumors after diagnosis is measured in weeks or months, even with surgery and chemotherapy. Hemangiosarcoma can occur in any breed, but there is an identified predisposition in German Shepherd Dogs, Labradors, and Golden Retrievers. Within my own circle of pet parent friends, last year we lost a Siberian husky, an Australian shepherd, a golden retriever, and my own miniature poodle, Tiny, to hemangiosarcoma.

What are the signs and symptoms to look out for? In the case of skin tumors, your veterinarian should evaluate any unusual growths on the skin and perform a biopsy if there is any suspicion of cancer. It’s a good idea to check your pet’s fur frequently, especially as he ages, for abnormal lumps or bumps. Many are benign, but only your vet and a pathologist can identify cancerous skin growths.

In the case of internal organ cancer, the signs can be much more subtle and sometimes non-existent. In the cardiac form of hemangiosarcoma, you may notice weakness, weight loss, loss of appetite, shortness of breath, or difficulty recovering from any kind of exertion. These can all be signs of simple aging, other heart or lung problems, or tumor growth. Again, a visit to your vet is for possible X-rays, ultrasound, CT scan, or other diagnostic scans to determine the cause of the problem. If not diagnosed, the heart tumor will eventually rupture and cause massive internal bleeding.

In the splenic form of hemangiosarcoma, unless the tumor is extremely large and can be felt on abdominal examination, the first warning sign could be a total collapse when the tumor ruptures. In Tiny’s case, he exhibited greater than usual “old man’s weakness” at home one night and was unable to stand up. He was seventeen at the time and had a bulging abdomen to begin with due to the loss of muscle tone associated with aging. I quickly took him to the veterinary emergency clinic (he never had his emergencies during regular vet clinic hours), where the doctor quickly touched his abdomen and removed bloody fluid. He told me about his suspicions that a splenic tumor had ruptured and recommended an ultrasound to confirm his diagnosis. The ultrasound showed a very large spleen, as well as some suspicious spots on the liver. We discussed the two options: surgery to remove the spleen and suspicious parts of its liver, or euthanasia. Given his age and all the possible complications, we made the difficult decision to say goodbye.

But, when Tiny was brought into the room for that final procedure, he had miraculously recovered from his breakdown, was very excited to see us, and started asking us to play with him. The vet suspected that the internal bleeding had stopped and that it had been re-transfused. After further discussion about the other alternatives and based on the fact that he seemed to be telling us that he was not ready to go yet, we took him home and scheduled a visit to the specialist early the next morning.

Tiny underwent a splenectomy and partial lobectomy of the liver, and came out of surgery with great success, especially given his age. We opted for a shortened, low-dose chemotherapy cycle, and for the rest of her life she took various mild medications like doxycycline and Deramaxx to help keep the cancer at bay. He also received acupuncture and Chinese herbal formulations in addition to Western medicine. Despite the six months or less that most hemangiosarcoma patients survive, Tiny lived another two and a half years until the cancer spread to his brain and mouth. When he started having trouble eating and started having seizures, it was time to help him cross the “Rainbow Bridge.” His outcome and length of survival with a good quality of life were unusually positive, but he was a fighter with a strong will to live.

Survival in hemangiosarcoma largely depends on how early it is detected and whether it is a superficial / skin lesion rather than an internal tumor. Treatment options can be limited, especially if a tumor ruptures, and diagnosis, surgery, and chemotherapy can be expensive. You know your dog better than anyone else and are in the best position to make informed decisions (with the help of your vet) about the best course of action if this deadly cancer strikes your dog.