Are Hypoallergenic Diets What They Seem?: Pet Food Allergies

A recent study reported that a number of hypoallergenic pet foods were actually contaminated with undeclared animal by-products that could cause allergic responses.

Hypoallergenic diets are an important diagnostic tool for determining pet food allergies, however the study discovered that 10 of the 12 limited antigen diets contained undeclared avian, mammalian or fish DNA (e.g. bone, protein and fats).

This contamination poses a problem for owners and vets trying to determine if a pet has a food allergy. A similar discovery has been made before.

What is a Hypoallergenic Diet?

Hypoallergenic diets (or limited antigen diets) are specifically formulated pet foods that are unlikely to trigger an allergic reaction in pets with food allergies. They avoid the use of common ingredients such as grains, soy, beef, chicken, etc. that are more likely to be responsible for allergies.

The diets usually contain either:

Novel ingredients – These are ingredients that your pet is unlikely to have come across before. For example, instead of chicken, the diet may contain pheasant. These uncommon ingredients are much less likely to trigger an allergic response because, for a food allergy to develop, an animal must be repeatedly exposed to a certain ingredient.
Hydrolysed proteins – These are small ‘pre-digested’ protein fragments that are highly digestible and have low allergenicity.

Typically a hypoallergenic diet is used to diagnose adverse food reactions (food allergies) as the novel ingredients are unlikely to cause an immune reaction. This is why the discovery of contaminated hypoallergenic diets is a concern.

Hypoallergenic diets are commercially available, however, some owners choose to opt for the home cooked alternative. By preparing your own hypoallergenic diet, you know exactly what your pet is being fed – however it can take a lot of commitment to prepare a meal for your pet everyday. There are plenty of recipes online and books available for owners wishing to do this however.

What are Adverse Food Reactions and Food Allergies?

An adverse food reaction or food allergy, is an immune response to certain antigens (e.g. proteins, fats) in the pet’s diet. The body’s immune system reacts to these harmless antigens as though they are in-fact harmful and releases compounds that cause irritation and inflammation.

An allergy will only develop after repeated exposure to an ingredient, which is why symptoms don’t tend to develop until 1-5 years of age. Food allergies often cause skin problems and predispose the pet to certain infections.

Symptoms of a food allergy can include:

  • Pruritus (itchy skin)
  • Skin infections
  • Ear infections
  • Gastrointestinal problems (diarrhoea, vomiting)

For more information about food allergies in pets see Adverse Food Reactions in Pets

How is a Food Allergy Diagnosed?

To effectively diagnose a food allergy, a limited antigen diet (hypoallergenic diet) must be fed to your pet. This essentially removes all potential allergens from the diet. If allergy symptoms ease after being fed the hypoallergenic diet, then a food allergy is the likely diagnosis.

The problem with diagnosing a food allergy is that adhering to the hypoallergenic diet can be difficult to follow – see this guide for tips. If the hypoallergenic diet is compromised, allergy symptoms may not clear up during the diagnosis period (usually up to 8 weeks), making diagnosis tricky.

To determine the exact ingredient that is causing your pet’s food allergy, your vet may guide you on how to slowly reintroduce potential allergens back in to the diet. For example, if allergy symptoms start to flare up after reintroducing soy to the diet, then soy will be the ingredient that is causing the allergy. From this point forward, you would want to eliminate soy from your pet’s diet.

Diagnosis can be compromised for a number of reasons, contaminated commercial hypoallergenic diets being one of those reasons. This is why the findings in the recent article are concerning.

The study is free to download and also points out some other complicating factors in diagnosing a food allergy

A Note About Food Intolerance

Just to note that an intolerance differs to an allergy. Whereas an allergy causes an immune response, an intolerance is a difficultly digesting certain foodstuffs.

Symptoms of intolerance differ slightly to an allergy. Food intolerances usually cause more digestive distress, such as bloating. For example, a pet with a lactose intolerance would have difficultly digesting the sugar (lactose) found primarily in dairy products.

Pet’s with a food intolerance would still benefit from limited antigen diet however, to determine the dietary ingredient that causes the digestive distress.

Recommendations for Pets with Suspected Food Allergies

The study highlights the importance of using reputable brands such as Royal Canin, Purina or Hill’s Prescription Diet to ensure that your hypoallergenic diets don’t contain contaminants that could complicate diagnosis of a food allergy or prevent symptoms from subsiding.

This guide on DogFoodAdvisor highlights some more recommended hypoallergenic diets.

If possible, you might want to create home-made meals for your pet. Essentially you will want to experiment with what works best for your pet, as not all food allergies are the same, monitoring for signs of allergy as you go.

If you have any advice on what has worked for your pet let us know in the comment section below.

 Image Credit – Ricky Romero

About James Watts

BSc Bioveterinary Science. Editor of PetSci. When I'm not writing, learning, discussing, or reading about animals, you know it's the weekend! Currently developing PetSci HealthTrak, the fast and easy way to monitor your pet's weight and calorie intake. HealthTrak offers a simple way to track your pet's progress, helping them achieve a healthy weight and a long, happy life.

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  1. Burgess Sensitive is great for all Cats and Dogs, but is particularly suited to those with a sensitive digestive system as the recipe is free from the usual ingredients that can upset your pet’s stomach. It contains just simple, high quality ingredients like tasty British turkey, Scottish Salmon and British Lamb we add prebiotics and rich sources of Omega 3’s for healthy digestion and a healthy skin and coat.

  2. My cat had terrible sores that would not heal and diarrhoea and the vet suggested hypoallergenic dry food. It has worked wonders. We were unable to get her spayed until the condition was sorted as her cuts would not heal..
    However, I think she’s pregnant! What should I do about her diet? I don’t want the cuts to start again by changing her diet but want her to be able to have a healthy pregnancy and be able to care for the kittens..

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