How to Determine if Your Dog Has Food Allergies

Three Methods:Identifying Common Food Allergy SymptomsEliminating Possible Food AllergensHaving Your Dog Examined by a Veterinarian

Just like their human counterparts, pets can be allergic to a large number of environmental factors and food substances. Allergies can begin at any age and in any dog breed. The most common symptoms of a food allergy in animals are itchy skin (especially around the head and forelegs, belly, and tail), hair loss, problems with the gastrointestinal system, or rarely, difficulty breathing..[1] If you suspect your dog has a food allergy, you'll need to diagnose the problem and take action to prevent your dog from exposure to that allergen.

Method 1
Identifying Common Food Allergy Symptoms

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    Check for skin reactions. Skin irritations and itchiness are the most commonly-reported symptoms of food allergies. See if your dog seems to be scratching frequently. Check under your dog's fur for rashes or hives if you notice your dog having dry, itchy skin.[2]
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    Look for ear infections. Ear and skin infections are commonly associated with food-based allergic reactions.[3] Excessive scratching of the ears, redness or swelling in or around the ears, and yellow/brown or bloody discharge are all signs of a possible ear infection.[4]
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    Track vomiting and diarrhea. If your dog frequently vomits after eating or has consistent diarrhea, he or she may be allergic to something in the provided diet, treats, or non-food products being eaten when unsupervised.[5]

Method 2
Eliminating Possible Food Allergens

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    Read the ingredient list. Certain dyes, fillers, and processed meats, grains, and proteins can cause allergies in dogs just as in humans. The most common allergens in dog food are beef, dairy, chicken/egg products, wheat, and soy. Taking note of the ingredients will allow you to perform an elimination diet if necessary.
    • Even if your dog isn't allergic to a certain food ingredient, your dog may have an intolerance to that ingredient. True allergies usually manifest with itching and skin irritation, whereas food intolerances typically result in strictly gastrointestinal issues.[6] No matter what your pet's reaction is, it's important to narrow down the problem ingredient and remove it from your pet's diet.
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    Conduct a dietary trial to test for allergies. Switch your dog from his current food to a food without the suspected allergen over the course of four days. Then feed him nothing but that food for a period of twelve weeks. This will help you determine with certainty what ingredient or additive is causing your pet's allergy. Trying a hypoallergenic diet is the best way to diagnose a dietary allergy.[7]
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    Ensure that your dog is not eating other items. It is essential to avoid all other foods while on the hypoallergenic diet, in order to avoid false results. If a dog eats animal feces, treats, or human food while on the trial, these could trigger the allergy, making it impossible to know if the dietary trial is working or not. Once triggered, the resulting inflammation in the bowel can stick around for weeks, so the trigger may be long gone but the symptoms persist. This is why the pet needs to stay on the special diet for a minimum of eight to twelve weeks.
    • Dogs may have symptoms that resemble allergic reactions after eating non-food items, such as cardboard, grass, garbage, animal feces, dead animals, and other items found outside or in the home.
    • Watch your dog carefully for a few days to make sure he or she is not consuming such items, and consider deterrence training if you catch him or her sneaking trash or eating other non-food products.
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    Try switching to organic dog food or food without fillers. Sometimes switching to a new dog food or to a brand that uses purer ingredients may reduce allergy symptoms and ease digestion.[8]
    • "Made with Organic" is not the same as organic. Only dog foods with ingredients that are between 95-100% organic may prominently display the Organic seal.[9]
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    Consider a temporary switch to whole food. Sometimes symptoms similar to an allergic reaction can be resolved with only a temporary switch to a basic diet of rice cooked with chicken or beef broth.[10]
    • A bland diet will allow the dog’s digestive system to regularize (unless one of these ingredients causes the allergy in your dog, in which case you will know very quickly which food causes the symptoms).[11]

Method 3
Having Your Dog Examined by a Veterinarian

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    Ask for advice on an elimination diet. Some veterinarians may be able to coach you through a temporary home-cooked food elimination diet for your dog.
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    Ask about a hydrolyzed protein diet. Specialized allergies such as this must be fed for about three months with no other foods, such as treats or table scraps, allowed at any time.[12]
    • Once symptoms resolve, you will gradually introduce individual foods until the allergen is identified. This type of diet will enable you to identify whether the allergy is truly caused by food.
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    Consider blood or skin tests. Certain tests may identify specific food allergens with little difficulty, while others may only give information about foods to which your dog does not have an allergy.
    • Blood tests are typically used to test for antigen-induced antibodies, which can then help your vet determine what antigen is causing your dog's reaction.[13] Consult with your veterinarian on what tests and procedures would work best for your pet.
    • There is a great deal of debate about how useful these tests are. The general conclusion is they aren't particularly helpful, and the gold standard remains putting the dog on a dietary trial.


  • Even if you have not changed your dog’s food, it is possible that the manufacturer has recalled certain batches of pet food due to contamination with bacteria, dust mites, or other potential allergens. Check the FDA’s Animal and Veterinary pet food recall link to find out if your pet’s food has been recalled.
  • Before making drastic changes to your dog’s diet, consider revoking additions such as biscuits, treats, and table scraps. You may also want to try avoiding the use of any spray deterrents applied to nails, fur, or household items that your dog may be licking or chewing.


  • Do not attempt to feed your dog a home-cooked meal on a permanent basis without instruction from a veterinarian. Dogs need a different nutritional balance from humans to be healthy, and without formal instruction few people are able to provide an adequate diet.
  • Consult your veterinarian or an emergency clinic immediately if your dog presents any severe, life-threatening symptoms.

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Categories: Feeding Dogs