Mast Cell Disease in Dogs

Mast cell disease is a type of cancer that affects dogs and other animals. It produces skin tumors, also known as mast cell tumors, and it accounts for 20 percent of skin tumors in dogs. If you can identify early signs of mast cell disease in your dog and seek treatment, some types of tumors can be removed before further problems occur.

  1. Definition

    • Mast cells are a part of the immune system of the body. They normally occur in the skin and other tissues of dogs, such as the respiratory tract and intestines. When parasites or other intruders invade the body, the immune system releases mast cells to attack them. Mast cells release toxins to get rid of the invading parasites. Though the cells are helpful, in some cases they start to rapidly multiply and release toxins into a dog's system even though there no parasite threats exist. This rapid growth creates the appearance of tumors on a dog's body.

    Symptoms

    • The appearance of tumors is an indication of mast cell disease. Mast cell tumors can appear anywhere on a dog's body, but they mostly appear on the trunk and limbs. The tumors have a variety of shapes, and they can be bumpy, smooth and even ulcerated. They may start off looking like a small bump or pimple. You may notice several other signs such as bleeding from the bump, and that the bump is getting larger. Also watch for systemic signs such as vomiting, blood in the stool and abnormalities in blood clotting.

    Diagnosis

    • To determine whether your dog's tumor is caused by the onset of mast cell disease, a vet must perform a biopsy. A biopsy involves collecting cells from the tumor using a needle and examining the cells under a microscope. The results will determine whether the cells are cancerous, and what further steps should be taken.

    Stages

    • Mass cell disease has five stages. Each stage determines how severe and advanced the cancer is in the dog's body, and what it will take to treat the cancer. The lower the stage, the better prognosis.

      In Stage 0, there is no lymph node involvement and one tumor is present that is partially removed.
      In Stage 1, no cancer is in the lymph nodes, and one tumor exists that is completely removed.
      In Stage 2, one tumor is in the skin and has spread to the lymph nodes.
      In Stage 3, there are multiple, deep skin tumors with or without spreading to the lymph nodes.
      In Stage 4, one or more tumors are present with metastasis in the skin, and lymph nodes are involved.

    Treatment

    • The treatment of mast cell disease includes surgery, radiation therapy and/or chemotherapy. Treatment for each dog will differ. How much the tumor has spread and the malignancy of the tumor will determine which combination of treatments is best. Surgical removal is the preferred treatment in most cases, especially for dogs with Stage 1 and Stage 2 mast cell disease. In some cases surgical removal may not be an option. Accordingly, radiation treatment is used instead. Radiation is most useful when tumors have not spread throughout the body. If the mast cell tumors have spread, chemotherapy in combination with surgery and radiation is the next option.

    New Developments

    • Palladia is a new drug used for dogs with mast cell disease. It is an orally administered prescription drug that works best with Stage 2 to Stage 3 mast cell cancer. Palladia works in two ways: it attacks and kills the cells responsible for the tumor, and it cuts off the blood supply to the tumor. There are strict regulations and guidelines for using this drug, so, it should only be administered to dogs that are under a veterinarian's care.