Mast Cell Tumor Dog Symptoms, Causes, Treatments and More!

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vet shaving around dog mast cell tumor on golden retriever

Unfortunately, dog cancer is a thing. The disease doesn’t spare our furry companions. In fact, mast cell tumor dog cancer is pretty common. It adds up to about 20 percent of all skin tumors in dogs. But it doesn’t have to be a death sentence. If Fido is diagnosed early, there are plenty of treatment and therapy options, including surgical intervention, for them.

It’s crucial that you know the symptoms so you can act fast. Keep reading to learn more about this topic and how you can help your furry friend.

What Is a Dog Mast Cell Tumor aka Mastocytoma?

All dogs have mast cells. They’re a normal type of blood cell involved in beating allergens and inflammation. But sometimes, those cells get out of wack. That’s when they become cancerous cells and we need to deal with them.

When these badly behaved mast cells appear in the skin, you can see that something’s wrong. When they multiply, they form lumps, which you can feel with your hand. These can appear anywhere on the skin, for instance, in the abdominal area or in the mucous membranes.

In short, you can find these wacky cells as cutaneous or subcutaneous tumors. That is to say, you can find mast cell tumor dog growth pretty much anywhere on your dog’s body.

Blood or Skin Cancer in Dogs: A Closer Look at Mast Cells

Mast cell tumors usually lead to skin cancer. But that’s not all. Sometimes, if the cells travel through the blood vessels, they can affect internal organs as well. For instance, they can lodge themselves in your pup’s gastrointestinal tract or liver.

vet performing mast cell tumor dog surgery

3 Causes of Mast Cell Tumors in Dogs

As is the case for most forms of cancer, scientists aren’t 100% sure about what causes it. Your dog’s veterinarian oncologist may have a clue, though.

Genetic Propensity

Doctors know genes have some role in who gets cancer and who doesn’t. This applies to all kinds of cancer, from liver to skin cancers.

Recently, we’ve learned that brachycephalic breeds are more likely to get mast cell tumor dog growths. In layman’s terms, that’s flat-faced breeds (such as Boston Terriers, Boxers, Pugs, and so on). But keep in mind any pup can get diagnosed with it during their lifetime.


There could also be some links between mast cell tumor dog growths and age. The older the dog, the more likely it is for them to get this type of skin cancer.


We don’t know for sure yet, but there may be environmental factors at play as well. For instance, excessive exposure to UV rays could make the mast cells go awry.

Lumps on Dogs and More: Diagnosis of a Mast Cell Tumor in Dogs

You don’t wake up one day and decide to do surgery on your dog. There are steps to take before it gets that serious. For starters, you’ll need to identify an abnormal growth of cells on Fido.

Then, the vet will step in and do a biopsy. Using a fine-needle aspiration technique, they’ll collect some of the cells. The excised mast cells go to a lab for testing. Only if the results come back positive for cancerous cells will your vet do surgery on Fido. This is also when you’ll learn of other treatment options.

sign of skin cancer in dogs

3 Signs and Symptoms to Look Out For!

Be on the lookout for any mast cell tumor dog symptoms. Catching them early could save your puppy’s life.

  1. Abnormal cutaneous growth. Run your hands down Fido’s body. Do you feel any weird lumps or nodules?
  2. New lesions on your dog’s skin. They’ll look different from when your dog gets into a scuffle with another pup. Are the lesions swollen? Is there ulcerated tissue?
  3. Sore spots on your dog’s skin. Some dogs feel the mast cell disease-ridden areas of their skin sore. Does your pup wince when you try to touch the lesions?

Treatment: How Can These Dog Tumors Be Treated?

If you’ve noticed any of these symptoms on your four-legged friend, don’t panic. The same can be said if your pup’s biopsy results come back positive. Fortunately, there are many treatment options for them. It’s not a death sentence by any means.

Right now, the main treatment avenue is surgery. Your dog’s oncologist will remove the mast cell tumor dog lumps. They could prescribe Fido a few meds (such as prednisone) to make sure all the cancerous cells are gone. If you’ve caught it early, that’s pretty much it.

Sometimes, it’s not that simple. The pocket of bad mast cells could have already spread to other organs. If that’s the case, Fido will have a poor prognosis. Yet, there are still ways to ensure Fido will get better soon. They can go through chemotherapy (with Vinblastine or Lomustine, for instance). This only applies to grade III mast cell tumor dog growths. You’ll know if this is your pup’s situation when the biopsy results come back.

We’re sure there will be more effective treatment options in the future. Once gene-editing is a thing, vets can correct the c-kit mutation, which is probably responsible for this type of cancer.

Prognosis: The Mast Cell Tumor Dog Life Expectancy

Every case is different, so prognostic factors vary. Some dogs live many years with mast cell cancer, even if it’s never treated. Some get cured in the blink of an eye, while others don’t live very long because of metastasis in their internal organs. It all depends on how advanced the cancer is and how well Fido responds to treatment. Talk to your vet, they’ll be able to give you a more informed opinion.

sleeping labrador with mast cell tumor in dogs

When to Take Your Dog for Testing

When you spot Fido’s abnormal cutaneous changes, it’s wise to visit a vet. They’ll be able to do a biopsy and test the tissue for cancer. Remember, the faster you act, the more effective the surgical procedures will be. Don’t lose hope. The odds and your veterinary oncologist’s skills are on Fido’s side.

Common Questions on Mast Cell Tumor in Dogs

How common are canine mast cell tumors?

Are mast cell tumors tied to genetics?

Is there a cure for these dog tumors?

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