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How To Know If My Dog Has a Food Allergy?

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Published on
Monday 25 September 2017
Last updated on
Tuesday 9 May 2023
Does my dog have a food allergy?
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Food allergies are universal irritants that can happen to anyone, even dogs. Some professionals may also refer to them as food intolerances or adverse food reactions. These reactions can develop at any point in life and are typically caused by specific ingredients or food additives.

At best, food-related allergens cause sufferers to feel mildly sick. At their worst, food allergies in dogs have the ability to completely incapacitate. Unfortunately, your pup can’t tell you when they’re having an adverse reaction so pet parents need to know the signs.

This starter pack and introduction into food allergies will help you identify if your dog has a food intolerance, then get you up to speed on how to remedy it. If you urgently need a new diet, check out our review of the best hypoallergenic dog foods.

What causes a dog food allergy?

There generally is not just one cause of a food allergy in dogs. It starts in your dog’s genetic makeup. Some breeds, like Cocker Spaniels, German Shepherds, and Irish Setters, are more prone to allergies than others. Dogs that are from a long line of breeders may also have certain food-related intolerances built into their bloodline.

If you’re going to buy from a breeder, do your research to see if there have been any complaints. Otherwise, adopting a mixed breed from a shelter or foster family can tell you about any known allergies ahead of time. Plus, mutt pups are often less likely to experience allergies since the stronger of the two genes typically to win out.

Scientists also believe that environmental factors like illness, surgery and antibiotics can also contribute to food intolerance. It is thought that early introduction to antibiotics can disrupt the gut’s immune system and microbiota. Once even minimally damaged, the digestive system is compromised in its ability to process certain foods or nutrients. While antibiotics could be responsible for creating a predisposition to certain allergies, it isn’t until those allergens are introduced to the system enough times that an adverse food reaction would be triggered for the first time.

What are the symptoms of a food allergy in dogs?

symptoms of food allergy in dogs
Signs and symptoms of food allergy in dogs.

It is important to treat your dog’s food allergy at the first sign of trouble. If left unaddressed, adverse food reactions can wreak havoc on your dog’s digestive system. Many dog food allergies also compromise the immune system, making it more difficult for your pup to fight off bacterial and viral infections.

Even if your dog has not previously presented symptoms of a food-related allergy, it doesn’t mean they’re totally out of the water. In fact, many food intolerances develop over the course of several years. Meaning, pet food that your dog once enjoyed has the potential to be problematic over time. Don’t have the very common thought amongst dog owners that “this kibble was fine yesterday, it must be fine today.

Stay vigilant and keep an eye out for any of the following symptoms of a dog food allergy:

  • Skin lesions or inflammation
  • Itchy ears or ear infections
  • Vomiting and diarrhea
  • Excessive gas
  • Weight loss
  • Constant itching
  • Fur loss

It’s important to note that while most people think a vomiting dog with diarrhea or one with gastrointestinal upset is the biggest allergy indicator, a dog’s skin and ears are far more telling of a potential onset of allergy. The skin is the largest eliminative organ in a dog’s body. When there’s a problem, allergens use a dog’s skin as their primary escape route. If your dog is losing patches of hair, itching frequently or has observable lesions on their face, paws, and ears you could be looking at food intolerance.

Are there dog food allergy tests?

It’s difficult, if not impossible, to test your pet for a specific food allergy. Most vets will tell you that blood tests are wholly ineffective.

However, you can have your vet perform other exams and tests to rule out specific, non-food related issues. For instance, if the lesions or ears are exuding discharge, take a sample in to be tested. You can also do some skin tests to assess your dog’s susceptibility to environmental allergies. Don’t expect a black and white list of what your dog is allergic to.

What is the dog elimination diet?

Currently, the only way to truly diagnose and treat a food allergy in dogs is to do a food trial. The most popular method is what’s called an elimination diet.

If your dog’s symptoms do not dissipate during the course of the elimination diet, check with your vet to see if they still suspect a food-related allergy. You can then change out the protein and carbohydrate source, beginning the food trial all over again until you find the right combination. It’s important to keep a journal of what you have tried so you will have a better idea of what to steer clear of.

Start by changing your dog’s food to a basic protein plus carbohydrate mixture they have not previously eaten. Read the label to identify the protein sources you need to stay away from. You may have to switch to something exotic like a rabbit or venison. The same goes for carbs.


You can search the internet for specialized elimination diet recipes that are designed to limit allergic responses, or you can make a special mixture at home where you can closely monitor all the ingredients in the mix. Doing it yourself is more recommended since you know exactly what goes into the bowl, and it has to be done only over a limited amount of time. Once you know what is triggering your dog’s allergic reaction, you can go back to a new kibble free of these food allergens.

Feed your pup the new formula for 3 to 12 weeks. In this time the dog’s digestive system will reset. Be careful, though! This also means no treats, table scraps, rawhides or bones. Even medications should be avoided unless they’re medically necessary. Only feed the dog with your preferred ‘limited antigen’ food of choice and fresh water!

Next, monitor your dog’s symptoms. Note whether they become reduced or eliminated entirely on the new diet. If so, reintroduce your dog to their original food and watch to see if issues return. They should present within a few days if it is a true food allergy. Once they do, you’ll have confirmation of food intolerance. Some vets refer to this process as ‘provocative testing’.

Find the guilty ingredient(s)

Once you know the dog has a food allergy, you want to switch back to the new formula of simple proteins with carbohydrates. Reintroduce some of the ingredients found in your dog’s old food one by one with 5 days in between. Monitor the dog’s symptoms and if you see food allergy symptoms again, the last ingredient you reintroduced is the guilty allergen.

Most dog owners and dog breeders skip this step because it takes a lot of time to figure out, but if you want to from then onwards choose the right dog food, you want to know what ingredients to completely avoid.

You can repeat the elimination diet as many times as you like until you have two to three regimes your dog is able to process symptom-free. You may be able to prevent your dog from developing any further allergies to these novel protein and carbohydrate meals by rotating them out every eight to 12 weeks.

Common food allergens for dogs

In general, the protein sources in many dog foods are some of the most well-known offenders. Beef products can be especially triggering for dog food allergy sufferers. While this may seem counterintuitive since dogs are primarily carnivores, if the quality of meat isn’t up to par it’s likely to cause upset.

Many pet owners also mistakenly assume that their dogs have iron stomachs and can put down almost anything. In truth, most dogs are lactose intolerant and the dairy products found in many common dog food brands can seriously disrupt their systems. Be careful if you are in need of a puppy milk replacer for nursing newborn pups.

In addition to beef and milk products, some other notable food allergens include:

  • Chicken
  • Lamb
  • Fish
  • Chicken eggs
  • Corn
  • Wheat
  • Soy

Just like humans, dogs can also have a severe gluten intolerance. Wheaten Terriers and Irish Setters are notorious for developing celiac in their lifetimes. This results in internal intestinal inflammation that can prevent the digestive system from properly absorbing nutrients. Outwardly this might result in poor coat conditions, rapid weight loss or persistent diarrhea. To remedy this, dogs must be strictly fed grain-free dog food. Feed and treats must be entirely devoid of wheat-derived products like rye, oats, barley.

Should you conclude your dog is allergic to common proteins like beef or chicken, make sure their food is supplemented with alternative protein sources like duck, salmon or whitefish and lamb. If you are able to prepare homemade dog meals, feel free to include offals and boney chunks of meat (chicken necks are loved by most dogs!)

Lastly, allergies in dogs can be traced back to food, environment, or both.

Treating your dog’s food allergy

Once you’ve determined, to the best of your ability, what your dog is allergic to, you can start to make daily dietary changes. Keeping them away from any known allergens is the only way to prevent a flare-up.

Generally speaking, feeding your dog a well-balanced diet is the best way to maintain a healthy system. When it comes to the dog food itself the fewer ingredients and additives the better. Make sure your dog can’t access another household pet’s food and don’t let anyone in the house give it table scraps. Check treats and chew toys thoroughly before letting your dog have a turn at them.

There is also some evidence to suggest that feeding puppies probiotics when they are young can help keep their digestive systems supplemented with enough good bacteria to ward off possible allergies that can develop later in life. Adult dogs may want to adopt a regimen of prebiotics to help feed these good bacteria and keep their systems regular.


Remember that dogs can develop additional food allergies over time so never assume that a new dietary regimen will last over the long term. Stay aware and in tune with your dog’s progress to avoid another slip.

Read all labels carefully before purchasing products and make sure any food you prepare for them at home is replete with the right amount of vitamins and minerals. Typically these recipes are best developed with the help of a vet or animal nutritionist instead of relying on the internet alone. Labels are often misleading, so be wary of marketing claims.

Taking a vested interest in your dog’s food allergy is just part of being a proactive dog owner. In doing so you are bound to spare you, fur baby, any unnecessary pain and can quickly get them on the road to recovery.

One comment on “How To Know If My Dog Has a Food Allergy?”

  1. Cloud9 Pets

    Dogs with chronic or recurring external ear infections should be evaluated for food allergies. If your dog vomits frequently, has diarrhea, irritated skin, a poor coat condition or hair loss, then he may have a food allergy. You may notice some of the following symptoms of a dog food allergy: Skin lesions or inflammation, Itchy ears or ear infections, Vomiting and diarrhea, Excessive gas, Weight loss constant itching, Fur loss and you do one more thing Dogs can have allergies just like humans can. … a sign that your dog has a food allergy or is sensitive to the shampoo you use to bathe them.

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