Allergic to Dogs and Allergies in Dogs Resource

Elimination Diet (Food Trial) and Hypoallergenic Dog Food

When diagnosing allergies in dogs, an allergy elimination diet (a.k.a. food trial) may be required in order to either rule in or out the possibility of a food allergy. Skin problems represent a common symptom of allergies in dogs and although the exact prevalence of food allergies in dogs is not known at present (Verlinden et al. 2007), it has been estimated to affect around 10-15% of canines.

Isolating the cause (source) of the troublesome allergen responsible for a food allergy is commonly achieved through a process of trial and error using an elimination diet. It can be a lengthy procedure given that some allergy symptoms, such as inflamed skin, may develop over many weeks or months and take equally as long to disappear when the allergen source is removed.

Although skin and blood tests are routinely used as a diagnostic tool for allergies, the results they yield can be variable and subject to various issues (See: Possible Issues Surrounding Allergy Tests). For example, although intradermal tests are very good for diagnosing inhalant allergies, many authoritative sources believe that both skin and blood tests cannot be considered diagnostic of food allergies or are ineffective e.g. NIAID 2010. It is for such reasons that, in the case of suspected food allergies, undertaking an elimination diet is considered a cornerstone in allergy diagnostics.

Before commencing a food allergy elimination diet, good practice dictates that one should have ruled out other conditions that may present similar symptoms e.g. other allergies, microbial infections or glandular and hormonal conditions.

Elimination Diet and Provocative Testing Principles

The rationale behind establishing whether a food allergy exists is based on provocative testing (manipulating variables to provoke the suspected condition):

Dog Allergies Elimination Diet and Provocative Testing

As inferred from the above diagram, provocative testing related to an elimination diet involves:

  1. Replacing the food suspected of causing the allergy problem with a hypoallergenic (low allergenic) product. An explanation of hypoallergenic food is provided towards the bottom of this page.
  2. Observing possible symptom changes. If the symptoms disappear or reduce significantly over time, then,
  3. The original food is reintroduced.
  4. Should the symptoms reappear, then it is probable that the original food was the source of the allergy problem. Thus, it is likely that the dog does indeed suffer from a food allergy.

If little change is observed in allergy symptoms (point 2 above) then a new trial should be started using a different hypoallergenic food source. If there is still no improvement in allergy symptoms, the cause of the problem is not usually food allergy-related. However, if a food allergy is still suspected, then other food sources can be tested individually over time.

In order to start from a ‘clean slate’ and minimize the risk of feeding the dog potential food allergens inadvertently, the animal will usually be put on a diet of only water and a single hypoallergenic food source for a minimum period. Opinions do vary amongst professionals as to what constitutes a minimum period; although some suggest 1 month, there is growing acceptance that it should be at least 2, but preferably 3 months long.

It is absolutely vital that the dog is restricted to this diet and is not fed anything else that may affect the trial. For example, this includes:

  • No treats or other animal products.
  • No flavorings as found in various medications and dog toothpaste etc., and
  • Prevent the dog from eating table dropped food or from roaming unsupervised outside.

Types of Elimination Diet For Dogs With Allergies

Although some people prefer to prepare homemade food for the food trial, many opt to use a commercially produced, low allergen food source from a reputable dog food manufacturer. It comes down to a question of personal choice based on the following pros and cons:

Homemade Food for Food Trials

Homemade Food for Food Trials ProsPros

  • You can use simple, straightforward ingredients that are less likely to trigger an allergic response in the majority of dogs e.g. boiled potatoes or sweet potatoes, brown rice, peas, yams and rabbit or duck. However, remember that any ingredient has the potential to trigger an allergic reaction in those predisposed to it e.g. a dog may be allergic to potatoes.
  • It is relatively easy to undertake provocative testing because you know exactly what is being included in the dog’s diet; by implementing a single protein and carbohydrate source you can minimize the variables. For example:
    If the initial basic diet produces no symptoms then add just 1 new ingredient. Continue the new diet for at least 2 months (ideally 3 months to be certain) and if no additional symptoms develop, add 1 new ingredient again. Should symptoms reappear, simply remove the last item and wait to see whether they gradually disappear. If so, it is highly probable that the last ingredient was responsible for triggering an allergic reaction.
    The process can then be repeated ad infinitum to build up a clear picture of what the dog is, and is not, allergic to. Such an approach may be the only viable option for dogs with severe food allergies or for those whose problems persist with commercially available hypoallergenic food.

Homemade Food for Food Trials ConsCons

  • Does the owner understand what constitutes a healthy, balanced diet so that the dog maintains the correct weight and receives an appropriate amount of nutrients, minerals and vitamins?
    For most people the answer is no. Therefore, this approach is best undertaken following advice from a veterinarian and preferably a specialist in animal nutrition (veterinarian nutritionist).
  • Less convenient (preparation or mixing is required).
  • More time-consuming.

Commercial (Hypoallergenic) Food for Food Trials

Commercial (Hypoallergenic) Food for Food Trials ProsPros

  • Controllable (measured volume gives a guaranteed balanced diet).
  • Convenient (no preparation or mixing required).
  • Less time-consuming.

Commercial (Hypoallergenic) Food for Food Trials ProsCons

  • One has to place trust in the manufacturer, its formulation and try to understand their terminology.
    For example, food suitable for allergy-prone dogs will usually have the term hypoallergenic associated with it e.g. here. However, in some cases the product may state it has a reduced or limited allergen/antigen formula, or that it is suitable for dogs with ‘sensitive digestion’. Unfortunately, terminology does vary between manufacturers and the latter terms may sometimes be used when referring to a product aimed at either a dog with a food allergy or food intolerance problem e.g. here. The difference between a food allergy and a food intolerance is explained in allergies in dogs symptoms – Gastrointestinal Issues.
    Therefore, given this topic can be confusing for consumers, anyone interested in this issue must apply due diligence and if in doubt, they should consult a qualified veterinarian for advice.
  • Even though the overall allergen level may be reduced, some products of this ilk do not contain just a single protein source.
    In such cases, they tend to utilize multiple protein sources, albeit modified variants, with the risk of introducing a mix of potential allergens. Therefore, depending on the dog in question, it is possible that even though their condition may improve, they may still experience persistent low-grade symptoms that may flare up on occasion e.g. mild skin problems.
  • Commercial hypoallergenic dog food aims to reduce the likelihood of a dog experiencing a food allergy; they cannot guarantee that your dog will not be allergic to an ingredient it contains. Consequently, you may have to try various brands and types before finding one that is suitable.
  • The marketing of ‘grain free’ products does not automatically confer allergen free because the issue of grain would only apply to those dogs who are predisposed to having an allergic reaction to it.
  • Such products may not be mainstream or readily available in some locations and can be considered relatively specialized e.g. a typical pet store that stocks a large range of dog food will usually only carry a very small percentage of those designed for dogs with allergies.

What is Hypoallergenic Dog Food?

Dog food labelled hypoallergenic tends to have the following characteristics:

  • A minimal palette of ingredients.
  • Highly digestible ingredients selected to avoid common food allergens (See also: Allergies in Dogs Causes).
  • Fewer additives.

By minimizing the number of ingredients, the pool of potential allergens in hypoallergenic products is reduced. By contrast, regular dog food contains a large number of protein and carbohydrate sources that can provoke an allergy response; they may contain beef/dairy/wheat-derived ingredients (an estimated 80% of canine food allergies are attributable to these), as well as other ingredients such as chicken, corn, egg, fish, turkey, lamb, pork, rice, soybeans and yeast.

Hypoallergenic dog food usually contains novel protein components (e.g. duck, kangaroo, pheasant, venison) that most dogs will not have been previously exposed to. They are therefore less likely to experience a reaction to them. Furthermore, the ingredients in these products may be modified to alter their physical and chemical properties and thereby minimize/eliminate the risk of an allergenic response occurring e.g. use broken down (hydrolyzed) proteins.

Moreover, when compared to regular dog food, commercial hypoallergenic food aims to exclude additives. Despite there being limited scientific literature concerning the negative impact of food additives (e.g. colorings, flavorings, preservatives, thickeners etc.) on dog allergies, in general, veterinarians/veterinary dermatologists consider additives as ‘suspected but difficult to prove’.

Hypoallergenic Dog Food Examples

The ingredients used in hypoallergenic products vary markedly between manufacturers. For the sake of comparison, we will look at two commercial hypoallergenic salmon-based dog food products that target the dog allergy market, thereby revealing contrasting approaches to tackling the problem:

Company: Arion
Product: Hypoallergenic
Main Ingredients:
Rice, Salmon Meat Meal, Animal Fat, Hydrolysed Salmon Protein, Yeast, Beet Pulp, Dried Antarctic Krill, Refined Fish Oil.
Vitamins and Minerals:
Vitamin A, Vitamin D3, Vitamin E, β-carotene, Iron, Zinc, Manganese, Copper, Iodine, Selenium, Calcium Carbonate, Sodium Chloride.

Company: Addiction
Product: Salmon Bleu
Main Ingredients:
Salmon Meal, Dried Potatoes, Dried Tapioca, Chicken Fat (Preserved with Mixed Tocopherols), Peas, Natural Flavor, Ground Flaxseed, Dried Kelp, Dried Cranberries, Dried Blueberries, Dried Spinach, Brewers Dried Yeast, Green Tea Extract, Rosemary Extract.
Vitamins and Minerals:
Vitamin A, Vitamin B1, Vitamin B2, Vitamin B3, Vitamin B5, Vitamin B6, Vitamin B9, Vitamin B12, Vitamin D3, Vitamin E, Sodium Chloride, Taurine, Choline Chloride, Magnesium Sulfate, Zinc Sulfate, Ferrous Sulfate, Calcium Carbonate, Copper Sulfate, Manganese Sulfate, Calcium Iodate, Cobalt Sulfate, Sodium Selenite.

Elimination Diet (Food Trial) and Hypoallergenic Food –  A Dog Food Allergy Panacea?

Although an elimination diet using either homemade or commercial hypoallergenic food can help identify problematic food sources that can be avoided thereafter, many veterinarians recommend that owners should aim to rotate protein sources and minimize grain intake in the long-term. A controlled diet will be required throughout the life of an allergy-prone dog but given time, the owner should aim for a balanced and diverse diet; unfortunately, keeping the animal on the same food source long-term can lead to them becoming allergic to it.

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