The Truth About Mast Cell Tumor Dog Life Expectancy

As a dog owner, one of your biggest fears is probably a cancer diagnosis. Whether you’re human or canine, the diagnosis is frightening.   While mast cell tumor dog life expectancy depends on the stage and grade of the tumor found, there are treatment options.


There’s Never an Easy Answer to Mast Cell Tumor Dog Life Expectancy.

The only one who can inform you of your dog’s prognosis is the veterinarian. He/she will be able to tell you which stage your dog is in, treatment options, and survival rates.

  • Mast cells are skin tumors that can be found on any part of a dog including the abdomen and perineum (the area between the dog’s genitals)
  • Mast cells come from bone marrow then settle into the connective tissues of the dog’s body.



DISCLAIMER: I want you to know that I’m not a veterinarian. The articles posted on this site have been researched and reported to the best of my ability.  You must speak to a licensed veterinarian for all medical concerns. 

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You didn’t cause the mast cell tumor in your dog!

That type of thinking creates unnecessary guilt.  Researchers haven’t been able to identify a single risk factor, although the tumors tend to present in larger breed dogs and older dogs (7 to 9 years of age, approximately).


The following breeds are thought to have a higher incidence of mast cell tumor diagnoses, with Boxers rating the highest.

  • Boxers *highest rate
  • Boston Terriers
  • Labrador Retrievers
  • Beagles
  • Schnauzers
  • Bulldogs
  • Pugs
  • Bullmastiffs
  • Cocker Spaniels
  • Bull Terriers
  • Staffordshire Terriers
  • Fox Terriers


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What is the life expectancy of a dog with a mast cell tumor?

Once a diagnosis has been confirmed, there are a number of things the veterinarian needs to do to determine the grade and stage of the tumor. These two things play a defining factor in your dog’s life expectancy.

The best-case scenario is when the tumor is found early, can be surgically removed and hasn’t spread.

  • Biopsy

 A piece of the tissue is drawn out for accurate diagnosis.

  • Blood Tests

The veterinarian will have blood tests ordered to help determine the staging of the disease.

  • Abdominal Ultrasound

The veterinarian may request an abdominal ultrasound. This is not a painful procedure for your dog.  High-frequency sound waves are transmitted, reflected, or absorbed by tissue.  This creates an echo that sends an image back to the technician.  Once all of the test results have returned, the veterinarian will be able to determine the grade and stage of the tumor.

Grade I:     Non-malignant and has not spread to other parts of the body.

Grade II:   Mast cell tumors are slightly deeper below the skin into the subcutaneous tissues and may be in a prime spot to start spreading.

Grade III:   At this point, mast cell tumors are deep into the tissues and are spreading.


Mast Cell Tumor Dog Life Expectancy

Dog and cat playing together on the grass at sunset








The next thing to discuss is the “staging” of the tumor. This will identify the number of tumors, where they are, and what need to happen to get the best prognosis.

Stage 0:  One tumor in the skin incompletely removed, with no lymph node involvement.

Stage I:  There is only one tumor that has not spread to the lump nodes.

Stage II:  One tumor in the skin that involves the lymph nodes.

Stage III:  Multiple large, deep skin tumors, with or without lymph  node involvement


A dog will live approximately 2 – 3 months with untreated mast cell tumors that are already widespread through the body. With chemotherapy, the dog could live up to 12 months.


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It’s not always easy to notice dog tumors in the very early stages.  You might notice an unusual lump while grooming your dog. If you do find a lump, it’s important to know that most lumps and bumps turn out to be benign (non-cancerous) fluid-filled sacs. Spend quality-time giving your dog a massage, carefully and gently inspecting the dog for any unusual lumps.

We know our dogs like the backs of our hands and if your instinct is telling you something isn’t right – whether you have visual evidence or not – book an appointment with the veterinarian.

If your dog begins sneezing over a period of time, gagging, or suddenly vomiting with no apparent cause, make an appointment with the veterinarian.

NOTE: Mast cell tumors can vary in size from day to day because of the level of inflammation in the skin. 


Will My Dog Need Surgery?

In order to get the best prognosis, the tumor will be surgically removed.  Surgery will also involve removing a wide area of tissue around the tumor to make sure they remove all of the cancerous cells.

Catching mast cell tumors before they have a chance to spread offers your dog the best outcome. Dogs that come in having already reached the stage of weight loss, black feces, and vomiting might be in the later stages of the disease with a poor outcome expected.




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