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Mast Cell Tumor Dog Life Expectancy


The minute you hear the word “cancer” or “tumor”, the first thing you want to know is the truth about mast cell tumor dog life expectancy. That’s normal. It’s also normal to have a ton of questions and to be a little afraid.

Life expectancy has a lot to do with how early the dog tumor was found and removed.  When dog tumors are caught early and surgically removed, your dog could have many more years to enjoy with you.

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

The options you choose depend on a few things, for example:

Your financial situation

Whether or not you have pet insurance

Whether the mast cell tumor has moved into the lymph nodes or beyond

The grade and stage of the tumor

There’s No 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. He or she can provide treatment options and survival rates. 

There have been cases where mast cell tumors have been removed with clean margins (no cancer cells left behind) and it’s important to remember that an article like this speaks in general terms. Your dog is unique and will have specific needs.

What Exactly ARE Mast Cell Dog Tumors?

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)

These cancerous tumors originate in bone marrow and then settle into the connective tissues of the dog’s body.

Immune Defense Function

Immune defense function is helped by mast cells which release histamines (the things responsible for creating allergic reactions, inflammation, and itchiness)

According to the Drake Center for Veterinary Care, “Mast cell tumors are especially common in dogs, accounting for approximately one skin tumor in every five dogs.”

Mast cell tumors commonly turn up on the skin, although they can actually occur wherever you find mast cells. That means, anywhere there is connective tissue within the body. I’m 

It’s estimated that HALF of all mast cell tumors are benign

This is very good news because it means that, in many cases, surgery takes care of the problem.  Getting a clean surgical margin is the key to reducing the possibility of a recurrence.

The trick is for surgeons to get the whole tumor in addition to a wide margin of tissue around the tumor.  They do this in case there are cancer cells that have extended a bit beyond the tumor itself.

Breeds Susceptible to Mast Cell Tumors:

Boxers *highest rate

Boston Terriers

Labrador Retrievers






Cocker Spaniels

Bull Terriers

Staffordshire Terriers

Fox Terriers

Symptoms Associated with Mast Cell Tumors

It’s common for older dogs to develop lumps and bumps, most of them benign. However, if you’re concerned about mast cell tumor dog life expectancy, it helps to understand a few things including symptoms to watch for.

Obviously, the first thing you’ve noticed is a lump. Mast cell  dog tumors are typically found on or just beneath the skin.

The problem with mast cell tumors is that they can take on a number of different appearances.

Sometimes there is no fur on the lump.

In advanced or more aggressive forms of mast cell tumors, your dog might be vomiting, unable to eat, and have signs of blood (black, tarry appearance) in the stool.

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

The Key to Long Mast Cell Tumor Dog Life Expectancy

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.  Only a veterinarian/surgeon who knows your dog and your dog’s medical history can give you an accurate prognosis.

Diagnostic tests will likely include some, or all, of the following:


A piece of the tissue is drawn out with a very fine needle and that tissue is examined under a microscope.

Blood Tests

The veterinarian will likely order a basic panel of blood tests. These blood tests help to determine kidney and liver function, whether the dog is anemic and whether the cells are circulating in the blood.  

Blood tests may not provide a clear indicator of mast cell tumors, but the information obtained is necessary in case surgery is in the dog’s future.

Lymph Node Examination

The veterinarian might feel for enlarged lymph nodes.  He/she is most likely to find enlarged lymph nodes close to the mast cell tumor site. 

It’s important for the doctor to know how many (if any) are affected by the tumor. It’s important to know this because the spleen stores the white blood cells necessary to fight viruses and infections.

Abdominal Ultrasound

Ultrasounds use sound waves to create images of organs within the body. A veterinarian may order an ultrasound to see if the mast cell tumor(s) have affected the spleen.

Bone Marrow Aspiration

This sounds pretty invasive to me. I would hazard a guess that veterinarians wouldn’t order this as a first-line diagnostic.

My guess is that a bone marrow aspiration would be ordered if there is a suspicion the tumor has metastasized to other organs or bone. 

A bone marrow aspiration would be another way of determining the grade and stage of the tumor.  See the grading process below.

Grading Process to Determine Mast Cell Tumor Dog Life Expectancy

Grade I:    

Non-malignant and has not spread to other parts of the body. This type has the greatest chance of survival, assuming that the entire tumor is successfully removed.  In grade 1 mast cell tumors, the tumor is found just under the skin.  It could be any size.

Grade II:  

Mast cell tumors that fall into the grade II category are also found under the skin. In this case, the tumor’s position is deeper and more likely to spread.  It might not have spread yet, however. This grade of mast cell tumor could be malignant.

Grade III:

This is not the grade you want your dog to get.  The tumor is deep within the tissues. This is much more aggressive and will require a lot more treatment including surgery, radiation therapy, and chemotherapy.  Note: The veterinarian/surgeon will determine the best treatment options.

Mast cells originate in bone marrow, as I mentioned at the top of the post.  Metastatic tumors can affect the lymph nodes and can show up as bone cancer.

Staging Process to Determine Mast Cell Tumor Dog Life Expectancy

Stage 0: 

One tumor in the skin with no lymph nodes involved.

Stage I: 

Similar to stage 0, there’s only one mast cell tumor and it has not spread.

Stage II: 

Stage II is getting a little more serious. In this case, the mast cell tumor does involve the lymph nodes.  The veterinarian will need to determine how many lymph nodes are affected and where.

Stage III: 

Multiple large, deep skin tumors, with or without lymph  node involvement.  At this stage, the prognosis is not wonderful. This is where some really tough decisions have to be made.  You can spend a lot of money and put your dog through extensive surgery, chemotherapy, and/or radiation, without the promise of a significant increase in lifespan.

Treatment Options that Affect Mast Cell Tumor Dog Life Expectancy

Surgery can cure your dog of mast cell carcinoma. In fact, if surgery is performed when the dog’s tumor is at stage 0 – grade 1, and a wide surgical margin is removed from the site, your dog may be completely cured.

It’s important that surgical excision include a fair amount of tissue bordering the cancer cells just in case any of the cells decided to drift.

Awkward Spaces for Some Mast Cell Tumors

Mast cell tumor dog life expectancy can be estimated in years when all cancer has been removed. 

Sometimes, however, the dog tumor appear in places that are tricky to get to. In that case, where the surgeon might not be able to get a wide enough margin, chemotherapy and radiation (either together or separately) might be suggested.

In fact, if the tumor is large and in a difficult place, the surgeon may suggest chemotherapy BEFORE surgery.

The hope is for the chemotherapy to reduce the size of the tumor. A smaller tumor might make it easier to get a wide surgical margin.

When Cancer Cells are Left Behind

If the surgery wasn’t able to remove all of the cancer cells, radiation therapy and chemotherapy combined might help shrink the tumor to assist in further surgery.

In cases where the tumor is too aggressive and has already begun to spread, chemotherapy and radiation might be suggested as a way to halt the malignancy, if only for a short remission

Supportive Medications for Mast Cell Tumors

There are a number of supportive therapies used in dogs with mast cell tumors including the following:


This steriod can kill cancer cells. It aids in decreasing inflammation in the body as well.  Side-effects of Prednisone could include increased thirst, increased hunger, nausea, vomiting, diarrhea, gastrointestinal irritation and possibly bleeding.


Name brands like Pepcid are often used to ease any side-effects related to the Prednisone.

It is important to recognize that most dogs can survive for a long time with mast cell cancer and can be cured. However, dogs with more aggressive mast cell tumors that have spread to the organs do not have a good long-term prognosis.

Mast Cell Tumor Dog Diets

We love our dogs and we will do whatever it takes to get them back on the road to good health. We want our dogs in our lives for as long as possible.  For that reason, dog owners are taking a hard look at canine diet choices.

Of course, some dogs also have a variety of allergies that lower their immune functioning.  

There seems to be a belief that a chronically lowered immune system can spawn nasty things like mast cell tumors in dogs.  Some veterinarians believe that a suppressed immune system could bring out cancer that was already there.  It’s not clear whether drugs that suppress the immune system actually cause cancer in dogs.

The All Raw Diet

This is by far the fastest growing trend right now with dog owners testing butcher-store raw, prepackaged raw meals, and straight off the farm carcass.

While it doesn’t seem to be popular among physicians and people who work for the Food & Drug Agency, it’s not slowing down the trend.  Is it good for your dog? I don’t know.

For more information on raw food diets, visit Raw Feeding Advice & Support forum on facebook.  Just do a search for “raw diet” forums and you’ll have your pick. 

2. Vegan Dog Food Diets are a Growing Trend

Most importantly, you don’t want to jump into any sudden diet change when the dog is already under duress.  Recovering from surgery could be considered under “duress”, or undue stress.

There’s nothing that says you have to go from Kibble one day to totally vegan the next. 

When switching your dog’s diet, don’t forget that there are many foods (including raw potatoes) that are considered toxic for dogs.

Dogs need Protein & Carbs

Dogs need adequate protein and carbohydrates for optimum health, so you want to really consider whether a vegan diet is going to offer that.

If you can be assured that your dog will get a good, balanced diet, than go for it. I always recommend that dog owners consult with a veterinarian, veterinarian technician, or dietician to make sure any nutritional-gaps are covered.

Bland Food Diet

Your dog probably won’t be very hungry immediately after surgery, but as he/she fights their way back to recovery, it’s a good idea not to make any drastic changes.

For the first few months after surgery, the veterinarian may suggest keeping the food bland or keeping on your dog’s current diet.

Many people in these specific dog diet facebook forums highly recommend a bland diet of boiled chicken.

It’s important to remember that one diet isn’t going to radically change mast cell tumor dog life expectancy. It could, however, make your dog healthier overall and boost the immune system. Doing this will certainly help in the recovery process.

 Allergen-Specific Mast Cell Tumor Dog Diets

The thing with allergies is that you really can’t feed or treat a dog based on symptoms alone. To avoid wasting a lot of time and money, it’s best to have a sound understanding of exactly what your dog is allergic too.

The last thing you want to do post mast cell tumor surgery is to feed your dog anything that might encourage the release of histamine within the body.

Mast Cell Tumor – Dog Drugs

This next section focuses on commonly used drugs to fight mast cell dog tumors.

One common fear is that mast cell tumor drugs will diminish their quality of life.  If you’ve had friends endure chemotherapy, you might wonder if it is worth it putting your dog through it.

Many dogs with mast cell tumors do not need chemotherapy!  In fact, most mast cell tumors are cured by surgery. The drugs that are used to treat them include many that are probably familiar to you.

Mast cell tumor dog drugs include:




Kinase inhibitors.


Prednisone is one of the most commonly used medications in the treatment of mast cell tumors. It can be used before and after surgery and is sometimes combined with other therapies including radiation and chemotherapy.

Prednisone is classed as a corticosteroid.  It reduces  inflammation and prevents the diseased mast cells from spreading. It is usually given as an oral tablet. Your veterinarian may use other injectable steroids at the time of surgery. Prednisone also has the positive side effect of increasing the appetite, which is very helpful in cases where a dog doesn’t feel like eating!

Other Common Side Effects of Prednisone include:

Increased thirst and urination

Excessive panting



Liver damage (increased liver enzymes)

Behavioral changes.

Your dog may be depressed or hyperactive while on this medication. These effects usually subside as the dose is tapered down.

Avoid giving aspirin or other anti-inflammatory drugs like  Rimadyl (carprofen) or Metacam (meloxicam while your dog is on oral steroids.  They can cause ulcers. Prednisone is prescribed at a high dose and reduced gradually during treatment.

Never stop using an oral steroid without tapering the dose first.  


Like steroids, antihistamines are a common component of MCT treatment. Your veterinarian may have you start giving oral Benadryl (diphenhydramine) prior to surgery, and will certainly use an injectable antihistamine at the time of surgery.

Some veterinarians recommend Benadryl because of its safety and lack of side effects.  Benadryl can be used long-term.


Mast cells and MCTs contain a lot of histamines, along with other chemicals that have differing effects on the body.

This histamine release is one reason that MCTs tend to rapidly change size from day to day.

Mast cell dog tumors release large amounts of histamines and other chemicals when poked, rubbed, or surgically removed. Histamine then moves into the bloodstream and surrounding tissue.

Histamine increases the risk of the mast cell spreading to other parts of the body.  Inflammation and welts are commonly seen near the tumor or in other locations. The histamines also cause the area to itch, similar to a mosquito bite.

Histamines can lead to ulcers of the digestive tract.

The combined effect of the histamines and the other chemicals released by the MCT can cause fluid to leak from the blood vessels into the surrounding tissues (edema), and reduce the blood’s ability to clot.

They can also cause dilation of the blood vessels and a lowering of your dog’s blood pressure. Using Benadryl will help prevent this cascade from getting started, and reduce the discomfort associated with having a MCT.

The most common side effect of Benadryl is drowsiness or sedation. Most dogs tolerate it quite well.


Pepcid (famotidine), Prilosec OTC (omeprazole) and Zantac (ranitidine) are oral antacids that are often used to treat the symptoms of a MCT. These antacids counteract the effect of the histamine release and reduce damage caused by excessive stomach acid.

Antacids protect the digestive tract from the effects of  prednisone and other medications. These are inexpensive, over-the-counter medications considered safe for long term use.

Your veterinarian will advise you on what dose is appropriate for your dog.

Chemotherapy and Mast Cell Tumors

Chemotherapy is defined as a drug that either directly kills cancer cells, or prevents cancer cells from dividing.  The National Canine Cancer Foundation is a great source of information.

Prednisone can be considered a form of chemotherapy, even though it has many other uses in both human and veterinary medicine.

Veterinarians have a different goal; they aim to relieve symptoms of the tumor and preserve the dog’s quality of life for as long as possible. This means that the drugs are used at a lower, less toxic dose than in humans.

When is Chemotherapy Recommended for Mast Cell Tumors?

Surgery alone is considered “curative” for most MCTs in dogs.

Your veterinarian will send the tissue to a lab for testing  after removal. The results of these tests will help your veterinarian determine if further treatments are needed. Laboratories use several different methods to grade and stage MCTs, so your dog’s results may be different from what we outline below.

Chemotherapy is usually considered if:

Testing shows a high grade tumor (some stage II, all stage III)

The tumor has spread to other parts of the body (metastasis)

The tumor has spread to a lymph node (metastasis)

The tumor is on a part of the body where it can’t be removed (nonresectable)

The dog has had multiple MCTs in a short amount of time

The removed tumor or biopsy is C-Kit positive

The veterinarian team will closely monitor your dog for side-effects.

Blood work, urinalysis and possibly fecal testing may need to be done frequently. These tests are necessary to be sure your dog is tolerating the medications and not experiencing any dangerous side effects.

Chemotherapy Toxicity

Chemotherapy drugs can be toxic to humans and other animals.  Wear gloves when handling to prevent accidental exposure.

Women who are, or may become, pregnant are at higher risk.Your veterinarian suggest specific precautions when cleaning up after your dog and disposing of their feces.

Chemotherapy for a MCT will not “cure” your dog. But it may relieve their discomfort and give you more time with them.

Every dog is different, and your dog’s prognosis will depend on his/her specific situation. However, many dogs who receive chemotherapy for MCTs live for several years beyond their initial diagnosis

Mast Cell Tumor Dog Drugs – Chemotherapy

There are many different drugs used as chemotherapy, and new drugs are being approved every year. The following drugs are the most commonly used chemotherapy drugs to treat MCTs in dogs; however, your veterinarian may recommend a different protocol based on your dog’s specific diagnosis and their personal experience.


Vinblastine is an injectable chemotherapy drug that is derived from the periwinkle plant. It works by binding to the proteins of dividing cells, preventing their division and killing them.

Since cancer cells rapidly divide, they are the prime targets of vinblastine. However, this drug works on all rapidly dividing cells in the dog’s body, including hair and intestinal cells.

One protocol calls for the vinblastine to be given via IV injection (into the vein) once a week for 8 weeks by the veterinarian, with the prednisone given at home daily.

Side effects of Vinblastine

Side effects can include fur loss, nausea, vomiting, diarrhea, constipation, jaw pain and irritation of the mouth. Some dogs can be sensitive or allergic to it.

Since it can suppress the immune system, dogs with active infections, leukemia, or low white blood cell counts should not take vinblastine. It is also not appropriate for dogs with liver disease.

Some medications should not be given with vinblastine, so be sure your veterinarian knows all of the drugs your dog is taking.

Lomustine (CCNU)

Like vinblastine, lomustine targets rapidly dividing cells, and it specifically disrupts the cell’s DNA and RNA replication.

This disruption both damages the cell, leading to its death, and prevents the cell from dividing. As with other chemotherapies, this drug can impact any rapidly dividing cells in your dog’s body. Fur loss and an upset stomach are common side effects.

Lomustine is given as an oral tablet and can be taken alone or with prednisone.   Lomustine is considere less potent than vinblastin. It may be used in cases where a more intensive protocol isn’t required.

Side effects of Lomustine include:

Appetite loss



Corneal changes

Oral irritation

Liver & kidney damage (less frequently)

Serious Side Effects

Bone marrow suppression is the most serious side effect. It can lead to anemia and other problems with your dog’s blood.


Chlorambucil binds the cell’s DNA and is often used to treat cancer of the immune system.  It works by binding to the cell’s DNA, preventing the cell from  replicating.

This drug suppresses the body’s ability to produce antibodies. It is an oral tablet that can be given daily or a few times a week, depending on the specific protocol your veterinarian is using. It is often used with other medications, particularly prednisone.

It is usually well tolerated dogs, and many veterinarians consider it a relatively safe form of chemotherapy.

Side effects include:



Bone marrow suppression

Loss of fur or slowed regrowth of fur.

Seizures are a rarer side effect, and some dogs may experience liver damage while taking it.

Toceranib Phosphate (Palladia)

This drug specifically targets MCTs in dogs. It is a tyrosine kinase inhibitor (TKI).  It works by directly killing the cancer cells and reducing the blood flow to the tumor.

This drug is particularly effective when the tumor has a genetic mutation called a C-Kit. Your veterinarian will have the lab test the removed tumor or biopsy sample for this mutation.
 The most common side effects are loss of appetite and diarrhea Nausea, vomiting, weight loss and bloody stools can also occur.

Watch out for these side effects!

Stop giving Toceranib and call your vet immediately if your dog: refuses to eat, is vomiting or has frequent diarrhea, has a black, tarry looking or bloody stool, is vomiting blood or has unexplained bruising or bleeding.

Alternatives to Chemotherapy

Many holistic and naturopathic veterinarians have developed non-drug treatments and therapies to manage MCTs that have metastasized or are not able to be removed through surgery.

These treatments can include a dietary change (particularly a raw or home cooked diet), acupuncture and massage to improve your dog’s blood circulation.  Various herbal or homeopathic remedies are also used.

Ideally you should find a veterinarian who can work as a team with your primary veterinarian to craft the best treatment regime for your dog’s MCT.

Holistic and naturopathic remedies may help with the side effects of surgery or conventional MCT treatments.

MCTs are the most common form of skin cancer in dogs, and 80% of MCTs can be adequately cured or controlled through surgery and radiation therapy. Even if your veterinarian recommends chemotherapy, your dog has a good chance of having a high quality of life for a while long time.


Jen Clifford

Lisa Theriault

What do you feed your dog and is it making any health impact that you can see?  email me directly at: [email protected]

I know that worrying about mast cell tumor dog life expectancy has been getting you down.  Remember that surgery is designed to remove the tumor along with a tissue border that could contain runaway cancer cells. 

Thank you for taking the time to read this post.  I hope you got some useful info from it! 

Please take a minute to share!

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