The Low-Down on Food Allergies In Dogs

dog with allergies

As you search for dog foods online or walk through the many aisles of dog food in the pet store, the options can seem overwhelming. And when you think your dog may have a food allergy, the information can be even more confusing. If your dog does indeed have a food allergy or sensitivity, you will need to try a new diet to try to calm their system down.

In this article, we’ll help you figure out how to go about the detective work of finding your dog’s particular food sensitivity, and give you the scoop on the many different options of grain-free, hydrolyzed, and limited ingredient dry dog foods.

How Do You Know If Your Dog Has A Food Allergy

A food allergy causes an immune response and can show up in a variety of ways. Food allergies can begin in dogs at any age, and can even start if your dog has been eating the same food for a while. Some breeds, like Bulldogs, are more prone to allergies than others.

A true food allergy causes an immediate allergic reaction, which can present as hives, facial swelling, or vomiting and diarrhea. When my son consumes walnuts hidden in baked goods, he immediately breaks out in hives and has an Epi-Pen-worthy response. Likewise, his cousin immediately throws up any nut that unknowingly passes his lips. He doesn’t think about it. His body just does it without a moment’s hesitation. A true allergy will elicit the same kind of response in dogs.

A food sensitivity builds gradually over time, presenting with skin conditions such as itchiness (most commonly on the ears, paws, rear end or stomach), hair loss, or poor skin and coat.

Other potential symptoms of a food sensitivity come from the gastrointestinal tract, and present as vomiting or diarrhea, chronic diarrhea, chronic gas, or an itchy rear end. Repeated infections in your dog’s ears or paws, or constant paw licking may also be a sign of a food sensitivity.


Yes, you can take your dog to the vet to have him tested for allergies, but this will not detect food sensitivities. It can also be costly.

Elimination Diet

The easiest way to figure out a food sensitivity is with an 8-12 week elimination diet. This involves feeding an extremely simplified diet (eliminating all but one protein source that the dog has not yet been exposed to in commercial dog food, such as rabbit, or eliminating all grains, or eliminating all but one carb, etc.) for the 8-12 weeks until symptoms of the sensitivity decline or disappear.

How Do You Know What To Eliminate?

The Grain-Free Movement

It seems the most popular trend right now is to go “Grain-Free.” Why the grain-free craze? Many argue that dogs have a shorter digestive tract than humans and are unable to digest grains. But quite a few experts disagree with this.

Dogs cannot digest uncooked grains, but through evolution, the domesticated dog has gained the ability to digest and utilize starch 28 times more effectively than wolves through the AMY2B gene.
It could be that with the rise in popularity of the gluten-free diet for humans, we have transitioned into the mindset that what is good for us is good for them. The grain-free market now accounts for nearly 30% of the pet food market in the US, totaling 2.2 billion in sales, and pet food manufacturers are happy to accommodate the grain-free demand.

Having said that, wheat is one of the top allergens found in commercial dog food, and grain-free food is an easy place to start an elimination diet simply because it eliminates all grains at once. If you see improvement over the 8-12 weeks, then one of the grains is most likely the culprit, and you can decide if you want to go to the trouble of adding certain grains, like oatmeal, back in, or just stick with what’s working if you have found a food your dog likes.

Protein Allergy

What people don’t realize is that many dogs are often allergic to the protein found in meat, with beef, chicken, and dairy products being the top culprits. If your dog does have an allergy to an animal protein, you will need to look for a food that has only a single protein source (only duck, or only rabbit), and it needs to be a protein source that your dog has not been exposed to before in their food. Make sure there is no dairy or egg in the recipe.

In this case, owners often seek out a “Limited Ingredient” dog food, but it’s important to read the label and be aware of what you’re trying to eliminate. Limited ingredient can mean more than one thing, as there is no standard in the pet food industry. It can mean it has only one protein source, as opposed to multiple protein sources. Or it may have only one carbohydrate or one fat source. It could also mean that it simply has a reduced number of ingredients compared to the company’s standard kibble products. Part of your detective work for determining your dog’s allergy will include knowing the ingredients in your dog’s current food and how it differs from the food you’re considering switching to.

Another option is to feed your dog a hydrolyzed protein prescription diet. In a hydrolyzed protein diet, the animal proteins are broken down into smaller parts – so small that the immune system no longer reacts to them. A hydrolyzed protein diet is generally by prescription only from your vet, and is a more expensive alternative to trying to eliminate specific ingredients from your dog’s food.

The Most Important Thing When Transitioning Your Dog’s Diet!

When switching to a different food, it is a process, not an immediate, cold-turkey switch. A dog’s food must be transitioned over time, typically 10 days, to prevent stomach upset and diarrhea. Start day 1 with 25% new food, 75% old food, and gradually increase the new while decreasing the old until the transition is complete on day 10. (Almost every bag of dog food stipulates this if you read the fine print.)

When I’m doing research for dog food articles, I often wonder if the owner writing negative reviews about their dog’s horrible gastrointestinal reactions to the new food have transitioned the food at all, or just dumped a whole scoop of the new food in their dog’s bowl and then let them have at it. The reality is, many dogs have sensitive stomachs. They’re not getting a wide variety of ingredients to process, which is why table scraps often give a dog the runs. Their system needs time to adjust, particularly if they’re already having trouble digesting their current food. We’re trying to calm things down through this process, not aggravate things further.

Other Things To Consider

If you’ve done a number of “eliminations” and your dog is not getting any better, it could be that your dog is experiencing some kind of environmental allergy. Consider whether it could be a new laundry detergent, flea and tick application, household product, or yard spray that is causing all of that itchiness.

Don’t forget to scrutinize the ingredients in the treats you may be giving your dog. Or if your dog goes to day camp, ask the employees not to give your dog their treats or consider bringing your own limited ingredient treats for the employees to reward your dog with.


This is obviously not an overnight process. As you progress through the weeks of your detective work, you may want to keep a log and track things like itchiness, regrowth of hair, or the appearance of your dog’s coat. Yes, this process takes commitment, but in the end, your pal is worth it.

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