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How to Diagnose and Handle Food Allergies in Dogs

Food allergies in dogs are tricky to diagnose — and it’s even more difficult to pinpoint exactly what’s triggering your pup’s allergic reactions.

Melvin Peña  |  Jul 21st 2017


The most common canine allergies vets see are reactions to the saliva in flea bites or ones that develop from exposure to household items like scented candles or cleaning chemicals. Food allergies in dogs are not as common. When a dog does develop an allergy, it does not manifest as a human allergy would with sneezing or watery eyes. Instead, a dog allergy is almost always written on the dog’s body.

Symptoms of dog allergies take external forms: ear infections, skin irritations, itching or rashes. As far as allergy relief goes, a dog’s only real options are to scratch, bite, chew or rub the affected areas. If a dog does develop a food allergy, and it goes unaddressed long enough, his reaction can eventually break skin, opening him up to secondary infections and making the original issue more difficult to diagnose and treat.

Dog food bowl.

Do you really know what’s in your dog’s food? Photography by Shutterstock.

Signs of food allergies in dogs

Development is the key word here. In dogs, food allergies take time and regular exposure to a specific allergen in order to cause symptoms. While they can develop in puppies, for most dogs, allergies to foods can show up any time between 3 and 12 years of age. Since fur obscures much of their skin, it’s fortunate that the reddish or inflamed skin that signals dogs’ allergic reactions are in spots that are easy to see:

  • Armpits
  • Ears
  • Face
  • Genital area
  • Toes

If your dog suddenly focuses on any of these areas, either with repetitive licking, biting, rubbing or scratching, these could be early signs of a food allergy. Vomiting or diarrhea can be signs of food allergies in dogs, but if you’ve switched your pup to a new food, it is much more likely that these are temporary reactions as your dog’s digestive system adjusts. Allergies do not manifest immediately, but over time and with repeated consumption of an allergen.

Proteins are the usual suspects of food allergies in dogs

The most common food allergies in dogs are usually reactions to proteins in the foods they eat. Food allergies begin when a dog’s digestive system fails to fully break down or process proteins in the foods they eat and to absorb needed nutrients from them. With time, their bodies begin interpreting these indigestible proteins as diseases. Items that can cause food allergies in dogs include:

  • Beef
  • Chicken
  • Venison
  • Lamb
  • Dairy products
  • Eggs
  • Corn
  • Flax seed
  • Rice
  • Soy
  • Wheat

Interestingly, meat is the culprit most of the time. Meat is more protein-rich than dairy, with any grain or vegetable a distant third. The staple grains in our list could be problematic if your dog’s diet consists solely of store-bought kibble. Grains like corn and rice tend to be major ingredients in most of the non-premium brands, whether for kibble integrity and cohesion or for nutritional value.  

Differences between food allergies and food intolerances

There’s a distinct difference between a food allergy and a food intolerance. Something like lactose intolerance does not mean that your dog cannot digest or process milk or dairy products at all; rather, it means they can, but only to a very limited extent. Constipation or loose stools are more typical digestive reactions to food intolerances than to food allergies in dogs.

Diagnosis and treatment of food allergies in dogs

Unless you’re personally preparing each of your dog’s meals and treats, a dog’s food allergy can be difficult to isolate on your own. If you believe your dog is experiencing the beginnings of a food allergy, your veterinarian has a range of approaches at her disposal. Blood tests, skin cultures and elimination trials can be tried individually or in concert to pinpoint the allergen that is affecting your dog.

Seeing these tests through to a definitive conclusion is not something that can be resolved in an afternoon, with a single visit to the vet or even over the course of a week. Often, whittling down the list of suspects to a definitive source can be a process lasting anywhere from one to three months.

If your dog does indeed have a food allergy, there’s a bit more wiggle room in what his digestive system can process and thrive on than there is, say, for a cat. Cats depend on proteins, especially those from meat, much more exclusively than dogs do. In cooperation with your vet or a dog dietary specialist, you can create a workable, non-allergenic diet for your dog and transition him onto it.

Read more about dogs and allergies on Dogster.com: