Hemangiosarcoma, or mast cell tumors, are among the most common tumors in dogs, but also among the most treatable. They might also be called mastocytomas.

The information you’re about to read applies to all forms of mast cell tumors. And the good news is that research shows that some 80% of dogs affected can be put into remission through modern treatment.

The mast cell cancer patient is generally an older, large breed dog. The first symptoms are usually one or more tumors on or underneath the dog’s skin. The visible tumors are the most treatable, but tumors can appear anywhere and the deeper they are, the more difficult they are to treat. Tumors can vary in size from day to day.

If your dog has exhibited loss of appetite, vomiting; sometimes bloody, diarrhea, abdominal pain, dark or black feces, itchiness, lethargy, anorexia, irregular heart rhythm and blood pressure, coughing, labored breathing, bleeding disorders, delayed wound healing, or enlarged lymph nodes -- these are symptoms of the more serious, metastasized mast cell tumors.

The prognosis depends on the stage and grade of the tumors. Skin tumors are generally very curable and after being removed, about half never reoccur. Other types such as groin, bone, and oral tumors are more difficult to cure. However, modern treatment, along with support of the pet’s immune system, has been shown to increase odds of remission dramatically. In many cases, this combination has produced long-term positive outcomes. Dogs that are otherwise healthy have a good chance to survive.

Your dog's diagnosis.

Your dog is depending on you. Once you’re beyond the initial shock of the diagnosis, it’s essential to act fast in turning this disease around. The quicker you start treatment, the more positive the outcome. The cancer can spread quickly though blood vessels, causing tumors almost anywhere in the body.

There are three basic forms of Hemangiosarcoma: dermal (skin), hypodermal (underneath the skin), and visceral (splenic or cardiac).

The dermal variety appear as dark skin lesions that may be raised and often appear on areas like the abdomen. These are the most curable because they’re easily spotted and have the best chance of being surgically removed. Still, 30% of dogs with dermal Hemangiosarcoma develop metastatic disease, so it’s important to treat the disease immediately.

Hypodermal, or under the skin, Hemangiosarcoma can occur anywhere on the body. The tumors may take the form of a soft or a firm mass. Sixty percent of dogs with this version of Hemangiosarcoma develop metastatic disease.

As you might surmise, visceral Hemangiosarcoma is the most virulent. Its blood blister-like formations are fragile and can bleed, disrupting normal organ function. Common symptoms are lethargy, loss of appetite, weight loss, difficulty breathing, pallor, or abdominal fluid. Regardless of where it originates, Visceral Hemangiosarcoma can spread quickly.

In the heart, bleeding can occur into the pericardium (the sac around the heart) and prevent the organ from working properly. Blood must be drained or the pressure will stop the heart from pumping. These tumors near the heart may be removed surgically if they’re identified while still small.

Surgery is typically followed by chemotherapy to prevent metastasis, and dogs treated with chemotherapy tend to live longer than dogs that are not.

It’s important to follow up surgery and chemotherapy with immune enhancement because the first two alone don’t address the underlying cause of the cancer: immune dysfunction.

But until the immune recognition response is triggered, your dog can’t overcome the cancer and recover fully.

Research into the combination of immune modulation therapy and conventional therapy has shown that ultimately it’s the patient's own immune system that overcomes the cancer.