Food Allergies in Dogs: Does My Dog Have Food Allergies?

Even if your dog has been eating the same diet for an extended period of time, they can develop an allergic reaction to their food. That’s because the body’s immune system takes time to develop antibodies to an ingredient. Our dermatology team shares the signs your dog may have a food allergy, how veterinary dermatologists diagnose food allergies, and what you can do to manage your dog’s food allergies.

What are Food Allergies in Dogs?

Food allergies in dogs, also known as cutaneous adverse food reaction (CAFR), occur when their immune system overreacts to certain ingredients in their diet, usually proteins. This immune response can lead to a variety of signs, including itching, gastrointestinal problems, and skin infections.

Food allergies in dogs are less common than environmental allergies, such as seasonal allergies, flea and tick allergies, pollen, and house dust mites.

Signs of Food Allergies in Dogs

Food allergies in dogs can manifest in various ways, and each dog may show different signs. Common signs for dogs include persistent itching, licking, or chewing different areas of their body, getting secondary yeast or bacterial skin or ear infections, or gastrointestinal signs like repeated vomiting, diarrhea, or excessive gas. 

These signs can also be associated with other allergies, such as environmental and flea bite allergies. Consult with a veterinarian to determine the underlying cause of your dog’s signs.

Common Food Allergies in Dogs

Although dogs can develop allergies to any protein or carbohydrate they have been exposed to, the most common food allergies for dogs are chicken, beef, dairy, wheat, soy, and eggs. The most common allergy is protein specific, but dogs can be allergic to more than one food ingredient.

How Do You Know if Your Dog Has Food Allergies?

The most reliable method for diagnosing food allergy (CAFR) in dogs is an elimination diet trial, which involves feeding a diet that does not contain any proteins your dog has been previously exposed to. This trial can take at least eight weeks and should be supervised by a veterinarian. During the trial, it is crucial to eliminate all other treats, supplements, and edible products to ensure accurate results.

There are two types of test diets that can be used for a food trial: “novel” protein diets and hydrolyzed protein diets. A novel protein diet consists of a protein source that your dog has not been previously exposed to, reducing the risk of an allergic reaction. A hydrolyzed protein diet involves proteins that have been modified to make them less allergenic. It’s important to note that not many over-the-counter diets meet the criteria for an appropriate food trial, so prescription diets are often recommended. These prescription diets are available in both dry and canned forms. In some cases, home cooking may be necessary.

While there are blood, saliva, and hair “tests” available commercially to diagnose food allergies in pets, they are not recommended. These tests are not accurate or reliable in determining food allergies in dogs. Therefore, it’s best to rely on a proper food trial under the guidance of a veterinarian to accurately diagnose and manage food allergies in dogs.

What Happens During a Food Trial for Dogs

Your veterinarian or veterinary dermatologist will guide you on how to successfully administer a food trial for your dog. Only feed your dog the prescribed diet and water and ensure that monthly preventatives, like heartworm and ectoparasite (flea) preventatives, are not flavored.

Here are a few tips when starting a food trial:

1. Before starting the new diet, make sure to thoroughly clean all food bowls with soap and water.
2. During feeding time, ensure that all family pets are separated. It’s important to pick up the bowls after feeding and not allow the pet on the trial to lick or eat from another pet’s bowl. If this happens, the trial must be restarted. Consider transitioning all household pets to the trial diet to avoid any cross-contamination. If different diets are fed, provide separate food and water bowls.
3. Gradually introduce the trial diet over a period of three to seven days to prevent stomach upset. Start by mixing equal quantities of your dog’s original diet with the new diet, gradually reducing the amount of the original diet. Keep one to two weeks’ worth of the original diet for rechallenge purposes if needed.
4. Avoid giving treats and any other potential allergen sources during the trial. Use topical or non-flavored heartworm and ectoparasite (flea) preventatives. Withhold supplements, oils, peanut butter, bones, and any other potential allergens. Consult your veterinarian for a list of permitted fruits and vegetables, but avoid feeding grapes, raisins, or corn.
5. Do not administer medications to your pet in any food or pill pockets. Always consult your veterinary dermatologist before giving any supplements or medications during the food trial.

Diagnostic food trials typically last for eight weeks. It takes about four weeks for the immune system to adjust to the new diet, and it may take up to eight weeks to see an improvement or reduction in your dog’s clinical signs.

This process may require a retrial based on the interpretation of the diagnostic food trial. The initial challenge involves using the original diet, and if confirmed, a lifelong prescribed diet may be recommended.

In certain cases, a veterinary dermatologist may suggest a rechallenge to pinpoint the specific allergen causing the reaction. Throughout this process, your dog will continue the trial diet while individual ingredients are introduced one at a time. Each introduced allergen will be fed for a period of 10-14 days to monitor for any signs of a flare-up.

The reintroduction phase may include various meats (chicken, turkey, beef, pork, white fish, salmon, lamb, etc.), grains and carbohydrates (rice, oat, wheat, etc.), dairy products (milk, cheese), and eggs.

Treating Food Allergies in Dogs

Once your dog’s allergen is identified, it is important to avoid all treats, supplements, and foods containing that allergen. Retail pet foods labeled as “limited-ingredient” may not be suitable for dogs with food allergies due to the potential risk of cross-contamination.

In addition to dietary changes, your veterinarian may prescribe medications to manage your dog’s symptoms. These may include allergy medications like Apoquel® or Cytopoint®, antihistamines, or steroids. Supplements such as omega fatty acids can also be beneficial in supporting your dog’s skin health and reducing inflammation.

Regular follow-up appointments with your veterinarian are essential to track your dog’s progress and make any necessary adjustments to their diet.

Read more about veterinary dermatology conditions.