I never realized how controversial the topic of grain free diets was until I read a few blogs about this subject. With that being said, I wanted to state a few disclaimers. The purpose of this post is not to criticize or promote the use of grain free diets. It is to educate owners on the relationship between skin allergies and grain free diets. There are two categories of people I attempting to reach with this article. The first category are owners who have pets who developed skin allergies and they are contemplating about switching to a grain free diet. The second category are owners thinking about placing their pet on a grain free diet in the hopes to avoid skin allergies.
So what is a grain free diet? This is a diet free of popular grains such as rice, soy, wheat, and corn. The belief is that omitting these ingredients benefits the pets overall health. There is improvement in digestive function, reduction in heart disease, and improvement in skin disease among other benefits according to advocates of this diet.
So how does a grain free diet relate to skin allergies? It is a popular belief that feeding a pet a grain free diet will help reduce or prevent skin allergies. Many of my clients who I see their pet for skin allergies report changing to a grain free diet hoping that it would fix the problem. Sometimes it works but many times it doesn’t. So why does it work for some clients and not others? What are they doing wrong?
Well let’s look at the diet specifically. Several studies in dogs and cats looked at the relationship of specific ingredients in association with skin allergies. The results showed that overall grains had the least association with adverse skin reaction in pets compared to animal proteins. The most common ingredients in dogs that caused skin allergies were beef, dairy, and wheat. Second most common was chicken, egg, lamb, or soy. Surprisingly corn, pork, rice, and fish were rarely found to cause an issue. So based on this information, a dog with an allergy to beef will not benefit from a beef based grain free diet.
So how do you find out if a diet change will work for you? First you need to determine the likelihood it is a food allergy by ruling out other causes if possible. Keep in mind that at least %20-%30 of pets can have both food and environmental allergies. There are some questions you may need to answer to help with this. Does your pet’s signs occur just during the warmer months or all year round? Skin allergies that worsen or only occur during the spring and summer months are more likely due to environmental allergens versus food. Does your pet have fleas? There are a few of my clients who bring in their pets in for skin problems who swear they never seen fleas on their pets. Then on my physical exam I find a flea or two. The problem is the client either lapsed on flea preventative or the pet isn’t on it at all. So before you decide to switch to a grain free diet for skin allergies make sure your pet is on a monthly flea preventative to rule out a flea allergy.
So if you have ruled out other possible causes of skin allergies and are convinced it is a food allergy so what is next? The ideal option would be allergy testing for food hypersensitivity. This testing is not 100% accurate but the results can help you be aware of what ingredients you need to avoid for your pet. This tends to be my first choice for dogs who have chronic issues with skin allergies. However, this test can be cost prohibitive to many owners. Another option is a food elimination trial. This involves feeding a diet that is considered “hypoallergenic” for a period of time. During this time, the pet is observed for improvement of signs which will can help confirm if a food allergy present. This is where most owners make mistakes when switching to a new diet. Common errors including not keeping the patient on the diet long enough to determine if it will work or not. They also feed treats or human snacks while on the new diet.
The most effective diet for food elimination trials are diets that are labelled as hypoallergenic. Examples of these diets include Hill’s z/d and Royal Canin Anallergenic diet. So what makes these diets different from commercial diets? Well protein digestibility is an important factor in whether a pet has an allergic reaction or not. Incompletely digested proteins can incite an allergic reaction because of residual proteins. Diets that are considered hypoallergenic are ones that have at least 87% protein digestibility. Also the newer veterinary therapeutic diets contain “protein hydrosylates” which are highly digestible proteins which leave little to no residues to cause an allergic reaction.
Once a diet is chosen for the food trial it is recommended that the pet remains on their original diet for at least 1-2 weeks. During this time a complete diary of what the pet eats should be maintained. Then the trial is initiated with the selected diet for a minimal of 4-6 weeks. During this time nothing additional should be fed to the pet including treats, flavored vitamin supplements, chewable medications, fatty acid supplements, and certain flavored toys. The usual diet is fed again and if allergies occur again within in 10-14 days then a food allergy is confirmed. Many owners fail at this because of how strict the protocol is.
In conclusion can a grain free diet help with allergic skin disease? Yes it can, but it is more likely that an animal protein will be involved based on the research. With the food allergy tests I have run during my career, there was always at least one animal protein listed as an allergen whether a grain was indicated or not . Sometimes there were 2 or 3. If a grain free diet is chosen for a food trial, it is recommended that a grain free diet with “novel proteins” are used. Novel animal proteins are meat that are not commonly used in commercial diets. These include meats like duck, rabbit, and venison. Just remember causes for skin allergies can be multifactorial. Narrowing these causes with the help of your veterinarian is essential to be successful in helping your pet with their allergies. Feel free to comment on your success and/or failure of using grain free diets with your pet’s skin allergies.