A Guide to Dog Food Allergies

Written by
Sophia Martinez
Published on
May 1, 2015
Updated on
January 28, 2024

Food allergies in dogs are caused by their immune systems responding negatively to proteins in commercial dog food, specifically the proteins present in vegetables and grains. Additives used in making dry and wet dog food may also contribute to a food allergy. Proteins found in fresh meat do not cause food allergies in dogs.

Other foods likely to incite an allergic response in dogs include eggs, dairy products, fish, corn, soy, and wheat. All of these ingredients are found in commercial wet and dry dog food.

All breeds of male and female dogs, as well as spayed, neutered and intact dogs, can suffer from food allergies. Puppies may develop a food allergy as young as six months while an older dog could suddenly start presenting food allergy symptoms as old as 12 or 13. Many dogs with protein-based food allergies often have pre-existing contact or inhalant allergies.

Is It a Food Allergy or Is It Food Intolerance?

Food allergies in canines and food intolerance produce different symptoms because they are different disorders. While a food allergy involves the immune system over-responding to proteins, food intolerance is strictly a gastrointestinal problem. Food intolerance in dogs is similar to humans getting an upset stomach, nausea, and diarrhea from eating fried or spicy foods.

Signs of Food Allergies in Dogs

The main symptom of a canine food allergy is itchy skin. When a flea infestation is ruled out, your dog may scratch continuously at his face, ears, feet, armpits and forelegs. He may also suffer recurring ear infections (especially yeast infections) and noticeable hair loss. Skin infections due to “hot spots” will respond favorably to antibiotics but return as soon as the medication is discontinued. In addition, some dogs with food allergies seem to have more bowel movements than dogs who do not have food allergies.

Other good signs your dog has a food allergy include having allergy symptoms all year long and not responding to steroid treatments provided by a veterinarian.

Diagnosing Canine Food Allergies

All other diseases causing symptoms similar to a food allergy must be ruled out before a vet can make a correct diagnosis. Diseases such as flea bite allergies, bacterial/yeast infections, parasitic hypersensitivity, atopy and sarcoptic mange may cause excessive itching, hair loss, hot spots and skin irritation.

Dogs suffering food allergies need to undergo elimination diets and food trials to determine the kind of food causing the allergy. Food trials consist of feeding a dog a new food source containing carbohydrates and proteins for 12 weeks. Examples of this kind of food source might be potatoes and venison or rice and rabbit meat. Some companies produce specialized dog food (hydrolyzed protein or limited antigen) with carbs and proteins broken down enough to prevent an allergic response. Dog owners should not give their dog medications, treats, rawhide chew bones or anything else except water and trial food.

Owners should also accompany their dog when they go outside to ensure the dog does not eat yard debris or garbage. Be aware that a food trial is effectively voided if the dog eats even a tiny scrap of food other than what he is supposed to be eating.

Eliminating Food Allergies in Dogs

Completion of food trials helps identify what ingredient is causing the allergy so the owner can eliminate it from their dog’s diet. If a dog’s allergy symptoms vanish during the food trial, then the owner knows it is an ingredient or ingredients contained in commercial dog food that is causing allergy symptoms. Consequently, owners of dogs allergic to brand-name dog food will need to feed their dog a homemade diet or purchase specially prepared dog food.

Implementing a Homemade Diet for Dogs

If a dog’s food allergy symptoms subside while he is eating a food trial diet of rabbit meat and potatoes, owners could then add a little beef to a homemade diet for dogs for a week or two to determine if their dog may be allergic to beef. Dog owners could gradually add other meat to enrich their dog’s diet, as long as he does not start showing allergy symptoms. Since homemade diets should be carefully balanced with the right amount of minerals, vitamins and other nutrients, dog owners should seek the assistance of a veterinary nutritionist when creating a homemade dog food diet.

Why Dogs Suffer Food Allergies

The canine GI tract (intestines, stomach, and mouth) protects dogs from hundreds of different allergens every day. However, nearly 75 percent of a dog’s immune system lies in the canine gastrointestinal system. When dogs swallow large chunks of food, enzymes and stomach acid break down these chunks and partially digests them before moving food into the small intestine. Here, food proteins are digested even further into amino acids so that specialized intestinal cells called enterocytes can either absorb the amino acids or reject them. Whole proteins (proteins that have not been broken down) absorbed in a dog’s intestines causes an adverse immune system reaction and symptoms of a dog food allergy.

The ability of the canine intestinal tract to stop whole proteins from being absorbed depends on the integrity of the lining of the gut (mucosal barrier). Comprised of the immune system and structural components, the mucosal barrier both prevents large protein absorption and recognizes harmful substances entering the GI tract. In addition, GI tract health also relies on normal enterocytes functioning, good protein digestion and the condition of canine immune cells living in the GI tract.

Called IgA cells, these immune cells either float freely or attach themselves to intestinal walls to stop whole proteins from interacting with enterocytes. IgA cells return whole proteins to the intestines for further digestion to help prevent an allergic response from the immune system. This means the ability of a dog’s intestines and stomach to effectively digest proteins largely dictates whether they are at risk for suffering dog food allergies in the future.

Keeping Your Dog Allergy Free

Promoting a healthy canine mucosal barrier, as well as providing dogs with a well-balanced, natural diet and exercise, is the best way for preventing dogs from experiencing symptoms of a dog food allergy.

And of course, it would not be Doggy’s Digest if we did not recommend that you give your dog a probiotic. It will help promote a balanced gut flora as well as increase the strength of your dog’s immune system.

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