Food is an essential part of a dog’s life, but what happens if your dog has a food allergy? How would you even diagnose this? Many people think their pets have food allergies, but it not as common as most people think. Food allergies only affect about 0.2% of dogs but it’s a big deal if your dog falls into that small group¹. Read on to learn more about uncovering and managing potential food allergies for your dog.

What are Dog Allergens?

When your dog’s immune system overreacts to a normally harmless substance (aka allergen), it is called an allergy. These reactions can be mild to severe and potentially even fatal.

Common environmental allergens for dogs include grasses, pollen, mold spores, dust mites, fleas, and medications. While not as common, some dogs have food allergies. The allergy is generally to the protein component of the diet. They can develop allergies at any point in their life — even after years of eating the same diet and being exposed to the same things. Your veterinarian can help you determine what your dog is reacting to.

Common Dog Food Allergies

Any protein or complex carbohydrate source in a diet can cause an allergy. The common food allergy triggers in dogs include:

• Beef
• Chicken
• Dairy

These have been the most common pet food ingredients for several decades, which is likely why they’re the most common triggers. As people begin to feed their dog a diet with other ingredients, the dog begins to develop allergies to other ingredients. That’s why it’s important to speak with your veterinarian before changing foods.

Other less common ingredients that can cause allergies include^2,3:

• Soy
• Rice
• Wheat
• Lamb

It is extremely rare for pets to have a true gluten allergy. However, documented cases have been found in Irish Setters and Border Terriers². That’s why grain free diets are likely to not be a solution to a dog’s food allergies. Also, there are reports of some grain free diets being harmful. Ask your veterinarian about the safety of grain free diets.

Signs of Food Allergies in Dogs

It can be tricky to determine whether your dog is reacting to food ingredients or something else, because the symptoms are similar.

The following are signs your dog may have a food allergy:

• Itching shown by licking, biting, chewing, scratching, or rubbing the skin of the face, paws, back, legs, rear end area, or ears

• Redness on the skin and ears
• Dry skin
• Increased oiliness of the skin and coat
• Recurring ear infections
• Chronic skin infections
• Increased self-grooming
• Hot spots
• Loss of hair
• Gastrointestinal issues, including vomiting, changes in stool (soft or loose), and gas
• Changes in the frequency of bowel movements

How to Diagnose Food Allergies in Dogs

Testing for food allergies is challenging. To date, the best method for veterinarians to diagnose food allergies is a diet elimination trial. This consists of feeding your dog a veterinary prescription diet. You can also try a homemade diet formulated by a veterinary dermatologist or nutritionist. Whether prescription or homemade, this diet should only contain a few ingredients and they should be ingredients that your dog has never been fed before. You can also try hydrolyzed protein ingredients. These proteins can hide from the immune system since they are broken down into very small pieces.

Your dog’s diet should have ingredients that include one protein and one carbohydrate with the addition of essential vitamins, minerals, and fats. This must be the only food your dog eats for a minimum of one month, but it usually takes up to 12 weeks to tell if it’s working or not. Don’t give them treats with other ingredients, as this will impact the purity of the trial. If you feed just one treat or a flavored medication with something the dog is allergic to, they may react for a while. Your veterinarian can put your dog on medication to help with itchiness at the beginning of the food trial, then stop the medication after a few weeks to see if the diet change is helping.

If your dog’s symptoms drastically improve during the strict diet elimination trial, they will be put back on their old diet. If their symptoms recur, this confirms an allergy to an ingredient in the old diet. Sometimes people opt not to do this step and just stay on the new diet.

To narrow the results to an individual food allergen, you’d go back to the elimination trial diet. Once your dog has improved again, you add one additional ingredient at a time from their old diet. You can connect any reaction they have to the specific ingredient you added. This is extremely helpful to confirm that your dog actually has food allergies as opposed to seasonal allergies that happened to coincide with the diet changes you made.

During the elimination diet trial, other allergy-related issues, like ear infections or skin infections, should be treated. They must be resolved before the trial ends so you can see if they recur when you switch back to the old diet.

How to Treat Food Allergies in Dogs

With the results of the elimination diet trial and confirmation of a food allergy, treatment is simply the avoidance of any of the food allergens that caused a reaction.

Can You Prevent Food Allergies for Your Dog?

Unfortunately, there’s no foolproof way to keep your dog from developing a food allergy. Some sources suggest rotating diets throughout their life, but this is actually harmful. It will drastically limit your options during diagnosis because an elimination trial requires your dog to only eat ingredients they have never been exposed to.