Understanding Food Intolerance in Dogs

Let’s unravel food intolerances, sensitivities and allergies in dogs; there is so much confusion. Here is our simple scientific overview

Allergy vs intolerance: spot the difference

德国赛车 Let’s start with a simple statement:

An allergy is not the same as a sensitivity which is also different to an intolerance.

However, many people use these terms interchangeably as though they are the same. (For “many people” also include several vets, leading medical bodies and nutritionists as well as dog owners looking for light on this hot topic)

How can there be so much confusion about something so common and so scientifically different. This guide will arm you with the scientific facts to differentiate these three conditions. So be prepared to wow your friends

Food Intolerance
Mirror, mirror on the wall; is it an allergy, a sensitivity or an intolerance?

Allergy Overview

德国赛车Let me give you a quick overview. You could die from an allergic response, but you won’t die from a sensitivity or an intolerance, and nor will your dog. People can sometimes describe themselves as gluten intolerant, but this is a whole other kettle of difficult to digest fish.  But by the same coin we all know how dangerous a peanut allergy can be: it could be fatal. We have all been on a flight where they made an announcement that no peanuts will be served. An allergic reaction is an immune response (specifically an IgE response) and is usually immediate. Think histamine release, swelling, redness, hives, itching, coughing, diarrhea and in the worst cases anaphylaxis. Typically these are on exposure to some “hyper allergens” like peanuts, bee venom and even strawberries or fish According to our friendly super vet consultant Dr Nick Thompson, President of the RFVS, very few dogs have allergies, even though some vets might tell you your dog is allergic to something, it is unlikely to be true. (see the reference sat the bottom)

Fast Facts on Allergies

  • An allergy is an immune system response. Specifically an IgE response
  • It is not a digestive, functional or gut issue so much as a blood issue. Your body is mounting an over-exaggerated immune response to something it believes is trying to kill you. The irony being that your body’s overreaction is the most fatal element
  • Some allergies need very careful management and medical advice
  • They are rarely resolved by nutrition, except by avoidance
  • A person or dog will ALWAYS have a reaction to something they are allergic to. They only thing that changes is the severity. There is interesting work in Australia giving peanut allergic kids microdoses of peanuts and building up, along with probiotics so they can tolerate this without the severe consequences (1)
  • Allergies can be grown out of. They can also become progressively worse
  • A slight allergy has similar symptoms to both a food sensitivity and a food intolerance, hence the confusion
All nuts can cause allergies, but peanuts are the most notorious

Food Sensitivities Overview

德国赛车A food sensitivity is a different type of immunoglobulin reaction, most typically an IgG response (although there are others) and is often acquired over time. The current thinking is this invariably involves leaky gut (aka. intestinal permeability) and undigested food particles passing into the bloodstream repeatedly. Over time, the body mistakes these ‘whole non-digested proteins’ as pathogens and reacts in the same way as it would in the presence of bacteria or a virus.

Scientists actually call food sensitivities ‘non-IgE mediated food hypersensitivity.’ That means that when you eat a food to which you are sensitive, you have a reaction but there is no raised histamine level in your blood. It also works differently in that a small amount of food you are allergic to will cause an immediate reaction, whilst a small amount of food you are sensitive to may not result in a reaction. This is important and highly relevant to how we can calm our sensitivities and even reduce them over time. It offers an important insight into our strategies later.

How a Food Sensitivity Works

德国赛车If your dog eats something and gets symptoms, how should we deal with it? That’s what we are addressing here. And let me reiterate that whilst many symptoms are common, NONE are ‘normal’. A symptom is a clue that something is going wrong and needs addressing. Ignoring them can make the symptoms worse, more pronounced and lead to chronic issues and potentially illness and disease… so let’s deal with it quickly and simply.

德国赛车 Some unwanted symptoms of potential issues the body may have with food include:

  • Itchy skin
  • Swollen knees
  • Arthritis
  • Lethargy

德国赛车Before we cover our Food Sensitivity Action Plan, lets also briefly explain the commonly misused and misunderstood term, ‘food intolerance’.

Food Intolerance Overview

A food intolerance is neither an IgE response, nor an IgG response. It is in fact not an immune response at all, it’s simply a functional or mechanical issue with digesting a particular food.

A classic example of this is a milk intolerance. This is nearly always due to lack of enzymes (lactase) which are able to digest the milk sugar (lactose). Symptoms of this include bloating, discomfort, and unwanted wind. This is different to a milk sensitivity which is due to the casein protein in cheese, milk, whey and other milk products. Classic milk sensitivity symptoms include facial redness, itchy skin and swelling around the face. 

Unfortunately, these are difficult to detect in dogs, except of course for the symptom of wind. We see countless dogs every week moving from ultra-processed food (UPF), often referred to as kibble, onto raw, as owners rejoice at their dog’s wind problem clearing up. This is because nearly all dogs will struggle to mechanically digest binders in UPFs such as wheat, lentils, peas and so on. This is a mechanical issue first and foremost, but also with immune responses which follow. The best way to stop this is to simply stop feeding these foods to your dog, in the same way you would with a person suffering with the same symptoms.

For more on the above, read my article The Gripe with grain, Why choose grain free dog food

This neatly leads us onto the last stop, our Food Sensitivity Action Plan.

The Food Sensitivity Action Plan

德国赛车Some dog owners have asked; “should I just start with one protein and slowly add them in?” The answer to this is NO. We are going to suggest a better method.

德国赛车Why? Because if you do that whilst your dog still has leaky gut, they will probably then develop an additional allergy to whichever protein their body does not agree with. This is not ideal. Variety is key.

德国赛车The best plan is to try to work out what your dog is sensitive to.

If your dog has been eating chicken or duck kibble for the last five years, this makes it easy. Begin by excluding these two. If you are not sure, start with the most likely, failing that, select any of the proteins they have been eating and cut one out. Just one.

Whilst you are doing this it is essential:

  1. The food you feed your dog is entirely grain-free, and while you are at it, also cut out corn soy, dairy and eggs. Simply check the packet to see what in the food. This is because all of these can contribute to leaky gut, which is how the proteins get into your dog’s blood stream undigested in the first place. [1]
  2. Avoid ultra-processed food. The proteins in this heated, treated, chemically altered foods are so unrecognisable to your dog’s immune system that they are more likely to trigger a reaction. Additionally, they normally come wrapped up with either grain or a similar cause of leaky gut, such as corn or lentils. If this wasn’t enough, there are ultra fine grains ‘of the biscuit’ which can easily cross your dog’s intestinal wall. See our podcast and blog on the dangers of cooked and treated proteins.
  3. You support your dog in healing its gut as much as possible with either dog friendly bone broth, digestive enzymes, probiotics, or a combination of these.

My quick tip

“I have trouble sourcing bone broth here in Andalusia and really don’t have the time to make it so I add in some Pasture raised Gelatin or collagen in warm water to my puppy’s food wherever she has had a stomach upset to help heal her gut faster.”

You can try this from Enhanced Nation:

Rotating Proteins

德国赛车Next… rotate! Select as many proteins as you feel your dog is not sensitive to, then put them on a four day cycle. For example, for four days, feed them nothing but the beef complete meal.

For the next four days, you would feed them nothing but the duck meal, and so on.. This period is just short enough to prevent your dog developing any further sensitivities whilst its gut is healing. You should do this with at least three to four proteins.

德国赛车Repeat this six to seven times , so at least 21 days, but preferably 28.

Monitor the symptoms. The best way to do this is to have a little notebook by the food cupboard, or take a picture on your smartphone of any skin issues, or both for a more accurate log. Keep it short, observant and simple.

Next, for one day only, you should add back in the suspect protein you believe causes the problem. Make sure this is only for one day. Then, return to the 4 day cycle with the other proteins. See what happens over the next 72 hours. If there are no symptoms, add the suspected protein back in for 2 days. If the symptom returns, stop and go back to the cycle.

This is a super simple way of approaching and testing it. 4 days rotation for 21-28 days. If you order all of your food online, in bulk and know that it is hypoallergenic (B&D or BARF equivalent), you are already halfway there.

德国赛车Obviously this is not intended as medical advice. I can however vouch for the fact that I have seen this work consistently in both humans and dogs.

As with any protocol, stick with the plan and let good things happen. Hypoallergenic is not always enough…but with our plan you have a roadmap to success.


Our reasonology section is where we explain all the science and data behind our arguments

What does Hypoallergenic mean?

Simply put, this is a term to describe foods that are less likely to cause an allergic reaction than ‘normal’ foods, whatever you consider ‘normal’. What we do know for sure is that some foods regularly pop up on allergy testing and are much more likely to cause a reaction than others. These are hyperallergenic foods.  For example, I have tested 2 people in the last 3 years who are not intolerant to egg white德国赛车. Egg white is the most allergenic food I have encountered, except for grain.

Everyone AND their dog is in some way intolerant to grains. Why choose grain free dog food

Dairy is very high on the allergy list.

Soy is incorrectly (IMHO) regularly included in ‘hypoallergenic’ foods as a substitute for grains. But actually it is really high in the histmamine foods list. This means it can create inflammation via a histamine reaction. Think of a wasp sting, inside you.

Corn seems to come up regularly. I am not sure why this is but I think it may be because its so high in sugars that it creates inflammation, leaky gut and then creates a reaction. This is virtually added to everything as a filler that it’s difficult not to develop a reaction to it. Once again, this is regularly added to supposedly hypoallergenic formulas by big food manufacturers, as an alternative to grain.

This leads me to my next point which is crucial…

There is a difference between a hyperallergenic food (one to avoid)  and one that is so common that nearly every dog has some intolerance to it. So, if a dog eats the same hypoallergenic food (low likelihood of reaction) every day AND has some leaky gut, you can put it down to this food. Hey presto => intolerance.

An example we see on the forums is that many owners believe chicken is a regular cause of food intolerance. This is CORRECT. Chicken is regularly a culprit.

However, chicken is pretty much ‘normal’ on the imaginary list of hyper-hypo foods. It is simply that it’s a very common ingredient in kibble and other dog foods. Quite often, owners will buy a 20kg bag of food and feed their dog nothing but this until it runs out.

Dr Nick Thompson explains how a raw diet helps

Find out how a raw food diet can help


Further reading on the website

Footnotes & References:
  1. Why choose grain free dog food[]

Rowan Sanderson


  • 德国赛车So, if chicken is a regular cause of food intolerance. Why have you put it into the majority of your food that isn’t the chicken complete.?

    • Hi there – thank you for reaching out. We have chicken in most of the puppy meals, but not in the adult ranges. Puppies, who haven’t been exposed to lots of ultra-processed food, are less likely to have an intolerance. Many dogs who react to a protein that is ultra-processed are able to eat it in it’s natural state, and a processed protein is more likely to cause a reaction than an unprocessed one. Cooking, particularly at high temperature, changes the shape of proteins making an immune response more likely. Those puppies who are unable to eat raw chicken for whatever reason can safely eat any of our adult meals. Within the puppy complete range the turkey, duck and salmon meals do not contain chicken. I hope this helps x

  • Hi, I wonder how I can try rotational feeding with a raw diet. I feed my cat a lot of different proteins, however I feed some on a daily and most on a weekly basis.
    德国赛车 Example: rabbit mince in the mornings on weekdays, a mouse in the afternoon daily, chicken bone broth for mixing with medication (the only way she’ll take it) and then for bones it’s a week of chicken, quail, and/or pidgeon. Organs it’s lam kidney and liver, duck heart and gizzards. Meat is beef, chicken, duck, turkey, horse, goat, deer, or rabbit, usually the same or 2 for 2 weeks before swapping. Twice a week a day old chick, 3 times a week a small portion of fish (rotated monthly sprat, herring, sardine, or mackerel)

    Is the best way to introduce rotational feeding to prevent allergies from developing to start doing X-free weeks? For example cutting out rabbit for a week and then feeding it again for 3 weeks almost daily in small amounts, then doing a rabbit free week again?
    德国赛车 Or would it be better to feed (for example) 5 days rabbit then a 2 day break? Or would those times be too long/short to have much effect?

    Looking forwards to hear your advice, thank you!

    • For rotational feeding, our Chief Nutritional Officer recommends feeding each protein for a 4 day period before moving on to the next x


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