The Elimination Diet for Dogs

Just as we humans have food allergies, our dogs suffer them too, though with certain differences. That is precisely what an elimination diet is for in dogs: to serve as the diagnosis and the treatment for this condition.

Take note of the key points we set out in this article to understand what food allergy in dogs looks like and how to run an elimination diet properly.

What a Food Allergy Looks Like

These are immune-mediated reactions to food proteins brought on by an inappropriate response from the immune system. The current tendency is to call them "adverse food reactions" rather than allergy.

Many people outside the veterinary world would expect food allergy in dogs to be similar to the human version, presenting very acutely and suddenly. That is not how it happens, though; dogs have chronic responses.

The main food allergens in dogs are beef, dairy, maize, soya, wheat and chicken.

What Is an Elimination Diet?

As the name suggests, it is a diet with no protein in common with the animal's current diet. That way, if there is a food allergy, the symptoms will clear up.

This makes it possible to confirm whether the dog has some kind of allergy or intolerance causing them health problems. One of the most common is food-related allergic dermatitis. Many cases of chronic diarrhoea are also proving to have an allergic origin, since they clear up on an elimination diet.

Although serological and intradermal tests exist, they are not considered diagnostic. Vets therefore tend to prefer elimination diets for dogs to detect reactions of this kind. The reason is that this method has proved to be one of the most reliable (90% sensitivity).

How Does an Elimination Diet Work?

There are three strategies for carrying it out:

1. Novel protein diets: This is a diet with proteins the animal does not eat in their usual diet, treats or home-made food. Since the protein causing the allergy disappears, the symptoms end up clearing. Some of the most widely used are horse, ostrich, rabbit and so on.
2. Hypoallergenic diets: Diets whose protein sources are relatively common but hydrolysed. This process is a partial digestion that reduces the size of these proteins until they cannot be detected by the immune system's antibodies. They are not hydrolysed enough to be entirely harmless, though (since hydrolysis is a very expensive process).
3. Anallergenic diets: Here the proteins are completely hydrolysed down to a size so small that they do not react with antibodies and do not produce food allergies.

For the curious, the cut-off point between hypoallergenic and anallergenic sits at 10kDa in size. These form part of a diagnostic protocol called elimination-challenge. It consists of reintroducing the previous diet once the symptoms have cleared, to confirm that it really was a food allergy.

Another option is to introduce the proteins one by one so as to establish which ones the dog is allergic to and which they are not.

How to Do It Properly

An elimination diet may not work if it is not applied correctly, because the gut is extremely sensitive. That is why doing it properly matters so much. The general keys you need to bear in mind to manage it are:

1. Keep this diet up for a minimum of 8 weeks, which is the time needed for the dog's body to clear the allergenic proteins and the immune response. Once that time has passed, the specialist will be able to assess whether there is improvement at skin and/or gastrointestinal level.
2. You need to be clear that while the dog is on this diet, they can only eat hypoallergenic foods. No treats, no snacks. No dental chews either, and no flavoured medicines or pastes.
3. Don't fall into the trap of thinking that a premium range of foods or preparing home-made food will — with complete certainty — prevent allergies from appearing. Even quality food can contain the food that is the source of the problem.
4. Introduce this diet gradually to avoid stomach problems. That way you will also reduce the chances of the dog rejecting the new foods.
5. Something very important to bear in mind is whether the kibble we give carries traces of other proteins not mentioned among the ingredients (by law, traces have to be declared). Even in minuscule amounts, these are enough to produce the adverse reaction in our animal. If home-made diets are being used, it will be very important to handle the food with completely clean, disinfected hands and utensils, since if food they are allergic to has been handled with them, that will be enough to trigger a reaction.

If the food allergy is finally confirmed thanks to the elimination diet, the dog's food will have to be changed permanently to a balanced diet suited to them, which need not necessarily be the same one used during the elimination.

Commercial Options for an Elimination Diet for Dogs

Bear in mind that the elimination diet is primarily diagnostic, and that the ideal is to find a diet with antigens that produce no allergic reaction; if it proves necessary, though, an elimination diet — anallergenic, hypoallergenic or novel protein — can be kept up for life. The ideal is to switch to a diet that does not produce the adverse reaction.

The commercial options available to us are:

• Prescription kibbles, whether hypoallergenic or anallergenic.
• Non-prescription kibbles with proteins different from those in the original diet.
• Other kinds of formulation with proteins different from the originals.

Beyond the elimination phase, these can be used as a maintenance diet.

Home-Made Elimination Diet for Dogs

If you want to prepare a home-made diet, we have to take into account every food our dog eats routinely and introduce a new protein into their diet that is either the sole protein source or part of those sources alongside other proteins they have never eaten.

Some meats available on the market that can serve the purpose are horse, rabbit, ostrich and other less conventional options. It calls for no special consideration beyond those of home-made diets generally, other than making it with new ingredients.

On another note, it is not only meats that contain protein: grains and some pulses have it too, so we also have to change these ingredients. If the diet is made with potato or carrot, these could be kept, since although they also have a protein component they do not usually cause allergies — but we should always keep watch.

As with commercial diets, beyond the elimination protocol, it can be used as a maintenance food.