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Featuring Demian Dressler, DVM and Sue Ettinger, DVM, Dip. ACVIM (Oncology), authors of The Dog Cancer Survival Guide

Food and Nutrition for Dogs with Mast Cell Tumors

Updated: August 24th, 2023


Dr. Dressler’s Dog Cancer Diet is appropriate for most dogs, but dogs with mast cell tumors need a few modifications. Read this if your dog needs a low-histamine diet.

We know that good nutrition is the foundation of health. The Dog Cancer Survival Guide devotes an entire chapter to a real food diet for our dogs battling cancer, advising both on the foods to give, and those to avoid.

Dogs with Mast Cell Tumors MAY Need a Low-Histamine Diet

While every cancer journey is a tough one, the diagnosis of Mast Cell Tumor (MCT) presents a bigger challenge when it comes to feeding.

In some (not all!) mast cell cancers, large amounts of histamine are released in the body, causing irritation and itching. In addition to itchies on the skin, the irritation can also be found in the gut.

That can cause nausea, vomiting, and diarrhea.

Antihistamines May Help (and Are Often Prescribed)

Most MCT treatment protocols include an antihistamine to help block histamine receptors.

So why look at diet, if you are giving an antihistamine?

Well, some foods have high histamine levels that can irritate the tummy tissues. Others may trigger the release of histamines in the body.

If your dog is itchy and/or having GI issues, making some of the modifications listed below might help.

The Dog Cancer Diet Is Fantastic for Mast Cell Tumors … With a Few Modifications

Even some of the healthiest, highest recommended foods Dr. Dressler recommends in his diet may not be appropriate for a dog with MCT.

If your dog is itchy and scratchy, Dr. Dressler’s post on Diets for Dogs with Mast Cell Tumors addresses this cause and effect in more depth.

Dr. Dressler has also provided insights for and reviewed this article, as well. The guidelines below will help you to modify his diet for your dog.

But first, let’s review when histamine is a problem … and when it is not.


Histamine … Is It a Problem for Your Dog?

First, it’s important to know that just because your dog has MCT doesn’t mean your dog is automatically having a problem with histamine levels.

Not all dogs with MCT have histamine problems!

Histamine is an important part of the body’s normal functioning. It’s made in several ways. It doesn’t just come from the diet.

That’s important to keep in mind. Changing the diet won’t necessarily eliminate histamine. It will just keep you from adding MORE histamine.

Put another way, if you have a sunburn, you don’t go out in the sun and try to get a tan, right? You avoid the sun until your burn has healed.

Same thing here. If your dog is in histamine overload, you avoid high histamine foods until those levels go down.

Signs Your Dog Is In Histamine Overload

So how do you know if your dog is in histamine overload, and you should change the diet?

If your dog is currently vomiting, itching, feeling sick, having reduced appetite, or swelling (welts) … histamine is probably in overload.

Signs Your Dog Is NOT In Histamine Overload

If your dog seems calm, isn’t itchy and scratchy, is eating and eliminating normally, has normal skin tone, and is basically acting fine … she is likely not in histamine overload.

Also, if there are no or few Mast Cell Tumors … for example if you’ve surgically removed them all … he’s almost certainly not in histamine overload.

Reducing dietary histamine is not necessary if your dog is not in histamine overload.

Why? Well, MOST of the ingredients in Dr. Dressler’s dog cancer diet are already on the low-histamine list. It’s already a pretty low-histamine diet as it is …

… and there are only a couple of ingredients that are high in histamine. And those are important sources of some vitamins and minerals … so if you don’t have to eliminate them, it’s way easier.

Balancing Act: Mast Cell Tumor Dogs May Go In and Out of Histamine Overload

In a way, histamine manages water flow in the body. When it is released, the area will swell, bringing immune activity.

For example, histamine is one of the things that causes a bug bite to swell up. It’s helping to heal. When it’s no longer needed, the body stops manufacturing it. The tissues stop swelling.

Mast cells that have tumors in them do not always manufacture and release more histamine. Sometimes, they don’t do that at all.

Sometimes they do, but then the antihistamine you give helps them to stop.

So this is not an all or nothing situation. You may not have to deal with histamine overload at all. Or you may have to deal with it for a couple weeks, and then stop.

How to Decide Whether to Use a Low Histamine Diet for Dogs with Mast Cell Tumors

So … it’s pretty simple.

If your dog has high histamine symptoms, reduce histamine in food. Again, you won’t be treating the problem … you just won’t be adding more histamine unnecessarily.

If your dog stops having symptoms (or if your dog never has any symptoms), you can resume a normal dog cancer diet. Again, dietary histamine is not likely going to trigger a problem if one doesn’t already exist.

The histamine problems in mast cell tumor dogs are coming from the cancer, not from the diet … reducing histamine in the diet is about reducing unnecessary excess, not about treating the cancer.

So you may only need to modify your dog’s diet for a little while. Once symptoms stop, and your dog is feeling better for a few days or a week, try adding one item back in and see how she does. If she tolerates it, you can continue feeding those few higher-histamine items.

If you see itching, or tummy upset start up again, you can remove those higher-histamine items again.

Rarely, a dog needs to have a low-histamine diet on a regular basis. In those cases, you’ll see itching and other symptoms start up as soon as you stop a low-histamine diet. In those cases, you want to keep a low-histamine diet for as long as necessary to keep your dog comfortable.

Like most things, this is all about balance and is not a yes/no/black/white topic.

The bottom line: Follow the symptoms, and feed accordingly.

Low Histamine Dietary Guidelines for Dogs with Mast Cell Tumors

It’s surprising just how tough it has been to find more thorough information on what foods to give a dog with MCT.

I honestly don’t know whether this is because no one wants to publish a recommended list, or no one has thought of it yet. But I know the need is there because our readers are asking for it.

Must-Understand Concepts for a Low Histamine Dog Cancer Diet

With Dr. Dressler’s expert input and my own background with animal nutrition, I’m going to give you a list of foods to avoid (and to choose).

As long as you promise to note the following:

  • Follow the recommended proportions/amounts in Dr. Dressler’s diet. Don’t go overboard on any ingredient in the yes list below. Five pounds of Brussels sprouts at a time is not good … even though they are on the “ok” list.
  • This list comes from human-food resources. The lists below were compiled by researching several human-food resources for histamine-restricted diets. Then, we screened those lists against the highest recommended foods for dogs with cancer. Why? Because dogs and humans share many similarities physiologically, and dogs are the preferred test subjects for human cancer research. What helps us in our diet usually helps them in their diet when it comes to cancer. Some of these sources are The Histamine and Tyramine Restricted Diet, and The Histamine Restricted Diet.
  • No list will ever be perfect or apply to every dog. This list contains foods that are generally safe and liked by dogs in general. That said, YOUR dog may not like some of these foods. Your dog may not be able to digest some of them well. Every dog is different, and what works for most may not work for your dog, and vice versa.
  • You will find conflicting information online. It would be great if every article you read agreed with every post, comment, or tweet. And it would be really great if every thing you read online agreed with what your veterinarian recommends. Well, that’s not real life. As you research histamine and mast cell tumors, you may find a list that recommends against one or more of the items below. You may find lists that contain other foods. You can find anything on the internet if you try hard enough. We researched low-histamine foods and high-histamine foods and then screened them against the dog cancer diet. These lists are not like other lists.
  • Don’t drive yourself (and your dog) crazy about histamine. Remember that it’s nearly impossible to eliminate everything that may trigger histamine. What we are trying to do here is reduce histamine load by not adding it via the diet. This is better than ignoring the problem, but it’s not addressing every histamine problem. Give yourself a break if your dog is still uncomfortable even if you change the food. Mast cell tumors are not fun.

The Definite ‘No’ List: High Histamine Foods to Avoid

Here is a list of foods or ingredients that should be completely avoided if possible if your dog is in histamine overload. A few of these are included in Dr. Dressler’s dog cancer diet, so I have listed modifications below. Otherwise, avoid:

All Fermented Foods
All Processed Foods
All Leftovers
All Fish**
All Berries***
All Stone Fruits (ex: Apricots)
All Cheese
Citrus Fruits
Yeast products like Bread
Cottage Cheese*
Walnuts and Pecans
Processed Oils with BHA/BHT
Anything Pickled
Anything with Vinegar

*Cottage cheese is included in Dr. Dressler’s dog cancer diet for its food-based calcium content. And, because dogs love it. If you are avoiding cottage cheese to reduce histamine, make sure you give chicken or turkey necks as outlined in the diet … or give a calcium supplement, or ground-up and boiled eggshells.

**Fish is on the list of proteins you could give in Dr. Dressler’s diet, and he also recommends giving sardines as treats. While your dog is avoiding histamine, do not use fish as your protein, and avoid sardines. (Sorry, puppy, I know they are delicious.)

***Berries that are dark and deeply colored, like raspberries, blueberries, and blackberries, are included in the diet as “optional healthy toppings.” While your dog is in histamine overload, don’t add them.

The Recommended ‘Yes’ List: Low Histamine Foods to Include

I hope you’ll be pleasantly surprised with this list. Most of these foods are already included in the dog cancer diet!

When you are reducing histamine, focus on using the following low-histamine foods:

Chicken Breasts
Lean Beef (trim off any fat)
Turkey Breasts
Chicken or Turkey Necks
Mung Beans
Organic, Rolled Oats (not instant)
Brown Rice (not instant)
Cooked Cabbage
Brussels Sprouts
Butternut Squash
Red and Yellow Bell Peppers
Pure Peanut Butter
Fresh Garlic Cloves (in small amounts of course)
Fresh Ginger
Coconut Oil
Krill Oil/Extra Virgin Olive Oil
Flaxseed/Linseed Oil

Now, if you look at that list, you will see about 90% of the foods listed in the dog cancer diet there. So, see? Most of the diet is good for cancer AND low in histamine.

As always, the better quality, organic meats are always better to serve, if possible. And please check out the cooking guidelines below as well.


Low Histamine Commercial Dog Food … ???

Unfortunately, even among the best-quality commercial dog foods, we have yet to find one that matches these recommendations.

So if your dog is showing symptoms of histamine overload, cooking for him or her is your best bet.

However, there are some really great foods available these days for when your dog is no longer in histamine overload. We have listed many in the Dog Cancer Shop and Dog Cancer Shop UK.

If a commercial food ever does come on the market that is of high quality and would be appropriate for dogs with histamine overload, we’ll update this article.

Special Cooking Considerations for a Low Histamine Diet

There are a couple of things to keep in mind as you cook for your dog. Histamines can be generated by the cooking process, for example.

Use Low Temperatures, and Don’t OverCook!

Histamine levels rise as meat cooks. And they continue to rise after meat is removed from the heat.

So, always cook your meat at low temperatures (below 300 degrees Fahrenheit).

And don’t overcook your meat.

For example, I’ve found the best way to cook chicken and turkey is to simmer the breasts in a large pot of water.

You get more meat for your money and you have a great broth too. Note: bone broth is high in histamines, but meat broth is not.

Freeze Meat, Don’t Refrigerate It

Histamines can continue to develop in the refrigerator, so refrigerating your cooked meat is not as good as freezing it. (Refrigerating cooked vegetables and grains is less troublesome.)

I freeze cooked meat immediately in meal-sized portions.

And don’t throw out that broth — it can be frozen in ice cube trays for treats. Or, you could use small containers that yield frozen brothcicles to melt down later for your dog’s delight. Freeze in containers up to a cup in size.

No Leftovers for a Low Histamine Diet

Leftovers are on the “no” list above, but it’s worth discussing this a little.

Many of us cook the dog cancer diet in a big batch and refrigerate it for a few days.

But if your dog has mast cell tumors, and you need a low-histamine diet, you might consider freezing every day’s portion individually.

That’s because histamines rise in food as they sit in the fridge.

Leftovers have higher histamines than fresh cooked foods. When you freeze the fresh-cooked food, you avoid excess histamine accumulation.

Again, vegetable and grain leftovers also develop histamines as they sit. But they do it more slowly than meat.

It really depends upon your own kitchen habits, but it may be most convenient to cook a big batch of food and then freeze it in portions. That way you know you are avoiding excess histamines that might develop in the fridge.

Are Fish & Krill Oil Supplements Safe for a Low Histamine Dog Cancer Diet?

If fish is high in histamines, is there cause for concern if you give your dog a fish oil supplement?

Possibly … although the processing of the fish to get its oil alters the original material, and likely removes any problematic metabolites that cause histamine reactions.

If you want to be very safe and make a conservative choice, avoid fish oil if your dog is in histamine overload.

What about krill oil?

In general, Dr. Dressler recommends krill oil over fish oil supplements for many reasons which he explains in the book. We have found that Mercola Krill Oil and Jarrow Formula Krill Oil report that any histamine is “below detectable levels” which is about as good as it can get.

Generally, the benefits of giving a high-quality krill oil for its anti-cancer properties outweigh the infinitesimal amount of histamine which may be present.

Krill oil (and fish oil) are important supplements in full spectrum cancer care. Giving krill oil, especially, is almost certainly better than avoiding it for the infintesimal level of histamines it may contain.

Both of these oils are available through the Dog Cancer Shop.


A Labor of Love for Your Dog with Mast Cell Tumors

All of this sounds like a lot of work, I know. But once you’re in the swing you can actually make your doggie food preparation a lot of fun.

When you have your ingredients, a little organization and an hour of time are all you need to prepare a week of food for your dog.

While your meat is cooking you can prepare a pot of organic, rolled oats or brown rice, and lightly cook the vegetables.

Store the meat portions in one container, oat/rice in another, and the various vegetables in a third.

Freeze the meat, refrigerate the others.

When food time nears you can select from each to make a delicious meal. Either thaw to room temperature if you have the time or warm in a microwave. Remember not to overheat.

I’ll bet your dog will be gazing wide-eyed until you put that bowl down.

I hope this helps those of you out there who were shaking your head in frustration. Take a deep breath, sit down with your dog and make that shopping list. You’re doing great!

Happy Tails!


Leave a Comment

  1. Leanne on February 14, 2023 at 8:02 pm

    My dog has a history of grade II MCTS. Removed 3 years ago, one without clean margins in his knee. This last 6 months 3 new growths have appeared. One in his chest, one tip of his tail and most recently one behind his ear which doubled in size fast. All ( except the ear one ) tested “ inconclusive “. I had an appointment to get the new ear one tested but Sunday he tore it up completely. Nightmare. Horrific and terrible endless bleeding a deep hole there. Sutures placed. I’m not sure if I should be giving the Benadryl round the clock. He is already extremely tired and no interest, but he eats. The Benadryl just makes him so tired. Since he disrupted aggregated the tumor I thought I needed to give it. He has off and on morning sickness since prior to the surgery 3 years ago and pukes bile. I feed home cooked defatted drained pork & hamburger, cooked broccoli, cauliflower, butternut squash & brussel sprouts. He is allergic to all birds poultry eggs all grains. I requested an appointment for removal of the tumor. I don’t want anymore FNAs done. I can’t determine if I should continue Benadryl after reading your information. I want to do what’s best of course. He seems very very tired. He quit drinking water on his own at least a year ago they think it could be due to traumatic event as it began after an unexplained puking episode for 12 hours. Because he had quit drinking water for 17 days after his MCT surgery 3 years ago but resumed. He is 10 1/2 years old and an extremely emotional dog. I’m lost as to what I should be doing right at this time. He tore it up 2 days ago and still has sutures.

  2. Debra Kendrick on November 13, 2022 at 6:04 am

    Is there a commercial food, not kibble, that is good for Mct dogs ? I am feeding him Orijen fish for kibble.

    • Molly Jacobson on November 16, 2022 at 3:26 pm

      Hi Debra, there is no commercial food that follows Dr. D’s guidelines. If you want to do a low-histamine diet with your dog, definitely look at another source of protein, since fish is on the “no” list above!

  3. Marie on July 28, 2022 at 11:19 am

    I am trying to manage my dog’s diet now that she was diagnosed with a mast cell tumor and put on benadryl. I am so glad that I found your article because I just purchased cottage cheese, yogurt and eggs for my dog and these are on the no list! I have eliminated carbohydrates from her diet because I read that cancer thrives on sugar. I was wondering about oatmeal and brown rice? Are these considered carbs because these are on the yes list. Also, can dogs digest flaxseed oil? Thank you for the article.

    • Molly Jacobson on July 29, 2022 at 10:23 am

      Oatmeal and brown rice are included in Dr. Dressler’s diet because they are complex carbs that do not spike blood sugar, and provide great energy, AND have anti-cancer benefits of their own. The “cancer thrives on sugar” line is an over-simplification of a much more complex discussion, which is why this whole subject gets really confusing, right? Flaxseed oil is not a high priority in Dr. Dressler’s approach but I believe it is digestible in general.

  4. Karen on April 5, 2022 at 2:18 pm

    If we remove cottage cheese from the diet, is more lean protein required?

    I find the diet confusing. In Dr Dresslers book he says “some ingredients should be cooked before weighed”. But he doesn’t say which ones!

    • Molly Jacobson on April 20, 2022 at 9:55 am

      Thanks for your feedback — we’ll be sure to look closely at the diet chapter in a future update to the book. The amounts listed in the ingredients list are all pre-cooking measurements.

  5. Allen Kollecker on February 22, 2022 at 3:48 pm

    Thank you for the excellent info! Well presented.
    Cheers from myself & Penny

  6. Marsha West on February 19, 2022 at 3:00 pm

    My vet told me do not heat in microwave. Can you speak to that? Also. I thought garlic was toxic to dogs yet you say give it to them. I’m confused

  7. Leanne on January 15, 2022 at 8:12 am

    My dog stopped drinking water a couple days after I eliminated dry kibble and started the anti cancer diet. Day 5 and so far refuses water. He looks at it like it’s sick. Backs away. He eats fine. I do add water to his food ( but his food is a soft diet now with removing kibble. No teeth mouth issue yet ). May have a new mast cell tumor in his upper chest wall. We are on a waiting list for 2nd apt to biopsy this newer lump. He had grade ii MTCs removed 2 years ago.

    • Molly Jacobson on January 15, 2022 at 12:49 pm

      Hi Leanne, it’s not unusual for dogs to adjust their intake of water based on their diet. The dog cancer diet has a LOT more water in it naturally than kibble does, so unless your dog seems dehydrated, I would just assume that it’s because he doesn’t need as much. My dog has been fed exclusively homecooked or dehydrated food for thirteen years, and the only time she drinks water is immediately after a walk or a particularly intense play session. A few months ago I had to use a medication that caused dehydration for a short time, and I was shocked at how much water she drank on it! If you are concerned, ask your veterinarian, of course. Glad to hear he’s doing well overall!

  8. Suzanne Babcock on November 20, 2021 at 10:37 am

    So happy to have found this info and article as we begin our journey for a corgi x Trixi has just been diagnosed with lymphoma at 4 yrs old. I’m horrified that we could loose her so going to use cannabidoids and essential oils to help her survive as long as we can.

  9. Catherine Michaels on November 15, 2021 at 2:28 pm

    We are feeding mast cell tumor boxer Rex raw fermented pork with goat milk from Answers company. He is 10 years old diagnosed mast cell tumor stage IV and given 4 months to live 10/20 after surgery for large mass removal. 1 year later he is still taking walks chasing a squirrel or some deer and wagging his tale The tumors are like polka dots now all over exterior coat And they bleed and it’s no fun.
    Pork is not on NO list or YES list. My questions is Pork horribley wrong? The company calls it a neutral meat Please inform me when time allows. Our dog at age 10 has never eaten veggies I have perused your site just abit and am actually crying as your experts are steering us in total different direction.
    My Cathy and I am Rex’s mom

    • Molly Jacobson on November 16, 2021 at 1:47 pm

      Hi Cathy! When it comes to nutrition, whatever is working for your dog works for your dog. Pork isn’t on the no or yes list because it’s not really “on” either list. That may be one reason the company you have been using uses it. If your dog tolerates it, I wouldn’t worry about it, personally. Veggies are a very important part of Dr. Dressler’s diet, because some of them really do help fight cancer. They also provide excellent food for probiotics, which is nice. You can find the diet in Dr. Dressler’s book. Mast Cell Tumors are a really tricky cancer, so reading the chapter on them may be helpful!

      Best wishes,

  10. Wendy on November 10, 2021 at 2:40 pm

    What is the serving size suggestion for the dog cancer diet? My girl is 9 and around 60 pounds

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