Food Allergies in Dogs

By Melissa Boldan, DVM on Jun. 6, 2023

woman feeding a yellow labrador retriever dog food

What Are Food Allergies in Dogs?

Food allergies are an immune response to ingredients in a dog's diet—an ingredient they are allergic to. This immune response usually becomes apparent over a prolonged amount of time rather than immediately after they try a food for the first time. Most dogs with true food allergies are actually allergic to a specific protein rather than a grain, as many assume. However, dogs can also be allergic to any ingredient in the diet itself.

When a dog with food allergies encounters a specific food they are allergic to, their immune system sees that protein as a foreign substance and mounts an immune system attack. This commonly causes itching, redness, and swelling. Food allergies are less common than environmental allergies, such as seasonal allergies and flea/tick allergies. In fact, only 0.2% of dogs are actually affected by food allergies.

Symptoms of Food Allergies in Dogs

Itchy skin
Frequent ear infections/skin infections
Hives
Licking/chewing feet
Diarrhea
Vomiting
Weight loss
Seizure disorders (rare)

Causes of Food Allergies in Dogs

Food allergies are caused by an overenthusiastic immune system reaction to specific protein. The immune system mistakenly treats the protein like a foreign substance and kicks into gear. This leads to inflammation, which causes physical changes in the dog's body, such as redness, swelling, itching, and increased tear or other fluid production, while the immune system tries to get rid of the “foreign” substance. This fluid production can be in the gastrointestinal tract as well, leading to diarrhea and/or vomiting.

There is a genetic component to all allergies. However, the exact mechanism of why allergies develop in some dogs and not in others is not fully understood.

Dogs can have allergies from an early age or they can develop them several years into life. While allergies can occur in any breed of dog at any age, some are more likely to have food allergies. Labrador Retrievers, Golden Retrievers, English Springer Spaniels, Cocker Spaniels, Collies, Miniature Schnauzers, and Shar-Pei are more prone to develop food allergies.

There are several ingredients that are often linked to food allergies in dogs. The most common allergy is to a specific protein, but many dogs are allergic to more than one food ingredient. The following have been commonly linked to food allergies in dogs:

Chicken
Beef
Dairy
Wheat
Soy
Eggs

How Veterinarians Diagnose Food Allergies in Dogs

Dogs are most often diagnosed with food allergies based on a physical exam, clinical signs, and their response to a food trial.

Your dog’s veterinarian may recommend that you complete a food trial with your pet. Food trials last eight to 12 weeks and must be followed exactly as prescribed. Be sure not to give any treats or other diets that may disrupt the results of the trial. Talk to your veterinarian about which heartworm and flea/tick prevention products are best during this time, as many have added beef or chicken protein for flavor. There are various ways that a food trial can be approached:

A prescription hydrolyzed protein diet. These diets have broken their proteins down to small particles so that they are unable to bind to the receptor and initiate the immune response.
An elimination diet. These diets have a single source protein/carbohydrate, and are either formulated by a veterinary nutritionist or are home-cooked diets made under the direction of a veterinarian.

Most elimination diets are not suitable for long-term feeding, and instead are used only to diagnose food allergies. If your dog’s skin/ear issues resolve, then you know that your dog has a food allergy and can move forward in finding a diet that they will thrive on long-term.

Novel “new,” protein/carbohydrate source diets. This is food that has unusual protein or carbohydrate sources and limited ingredients that may cause an allergic reaction.
Skin support diets. These are fortified with bioactives and phytonutrients to minimize the immune system's response.

Food trials or elimination diets are the best way to diagnose food allergies. There are diagnostic tests on the market, but many questions remain regarding their accuracy.

Treatment of Food Allergies in Dogs

Most food allergies are treated with a change in diet. It is very common for dogs with food allergies to also have environmental allergies. They may be prescribed allergy medications like Apoquel^®, Cytopoint^®, antihistamines, or steroids, in addition to a special diet.

Several supplements may be beneficial to dogs with allergies as well. These include omega fatty acids to boost the natural barrier function of the skin, and products including:

Vetoquinol^® Omega
Nutramax^® Welactin
EicosaDerm^TM

Best Food Diet for Dogs with Food Allergies

Many diets on the market can help to manage your dog’s allergies. Allergies are specific to the individual dog, so there is no one “best diet.” The best diet is the food that contains ingredients that your dog is not allergic to and is balanced and formulated for optimal health. The following list includes several diets that many allergy dogs have found relief with, including:

Recovery and Management of Food Allergies in Dogs

Food allergies cannot be cured, but they can be well-managed long term with appropriate diet therapy and avoidance of allergic ingredients. If your dog has a food allergy, be sure to watch dog food labels closely, especially with treats, so you don’t accidentally give them anything considered allergenic. Prescription treats EW on the market, and some pet parents find it helpful to use raw baby carrots or green beans for treats in a pinch.

If your dog has food allergies and is undergoing a diet trial, expect it to last eight to 12 weeks before you can see an improvement. Reduction in licking and chewing may be seen in the first four weeks, but other dogs may take up to 12 weeks before you see any improvement.