Mast Cell Tumor Dog Diagnosis

A mast cell tumor in a dog is a common dog cancer that usually occurs in the skin. They can spread easily to other parts of the body, including the:

  • liver
  • spleen
  • bone marrow
  • lymph nodes

Vets don't really understand what causes mast cell tumors. Here's what you should know about the symptoms and diagnosis of this common dog cancer.

Symptoms of Mast Cell Tumors in Dogs

Mast cell tumors in dogs generally develop on the skin. They occur when mast cells, a type of cell responsible for regulating inflammation and the repair of damaged tissues, mutate and grow out of control. Mast cell tumors make up about 20% of all dog skin tumors. Mast cell tumors can occur in dogs of any age, breed or gender, but they're most common in dogs older than eight years of age.

If your dog develops mast cell tumors, you'll notice rounded lumps on his skin. Your dog may lose his appetite and he may begin vomiting. Mast cells can spread easily to the digestive tract, causing internal bleeding and black, tarry stools. Your dog could experience pain in the abdomen.

Diagnosing Mast Cell Tumors in Dogs

Your vet will need a complete medical history and a thorough physical exam in order to make a diagnosis of mast cell tumors. He'll use a fine needle aspiration to remove tissues from your dog's lymph nodes, and from his tumors, in order to perform diagnostic biopsies. Blood tests and biochemistry profiles can help your vet determine if your dog's immune system is reacting to the presence of cancer. In some dogs with mast cell tumors, mast cells can be found circulating in the blood.

Your vet may take ultrasounds and X-rays to evaluate the extent of damage to internal organs such as the kidneys and liver. If your vet suspects that your dog's mast cell disease has spread throughout his body, then biopsies of the spleen, liver, bone marrow and other organs might be necessary. Your vet may even remove entire skin tumors for examination in the lab.

Treating Mast Cell Tumors in Dogs

If your dog's mast cell tumors have not yet spread to other parts of his body, then surgical removal of the tumors could be the only treatment he'll need. Your vet may choose to use radiation therapy to halt or reverse the growth of inoperable skin tumors. Chemotherapy can be of benefit to dogs whose mast cell tumors have already spread throughout the body.

Vets don't know what causes mast cell tumors, so it's difficult to prevent this disease. Early detection is key to helping your dog recover from mast cell tumors. If you notice any lumps, bumps or growths on your dog's skin, skin veterinary care immediately. Most dog skin tumors aren't cancerous, but if your dog does develop a cancerous skin tumor, his chances of surviving the disease will be much higher if you seek treatment before the disease has a chance to spread.