How to Identify Dog Food Allergies

Dr. Jason Gagné, DVM, DACVIM
By Dr. Jason Gagné, DVM, DACVIM
Updated: 5/9/20242-4 minutes
Allergies in dogs

It might surprise you to learn dogs can develop allergies to foods at any time—even after years of eating a certain ingredient. So, if your pet suddenly develops gastrointestinal (GI) issues and/or skin conditions, the culprit could be their dog food.   

(Note, however, that dog food allergies are far less common than skin and environmental allergies.)

Of course, allergies can develop at different life stages and across a variety of breeds, at any time.

Wondering if your dog has become allergic to their food? Read on to learn more about food allergies, their symptoms and steps you can take to provide some relief for your pet.

Food Allergy vs. Food Intolerance

A food allergy occurs when your dog’s immune system engages with a certain molecule, or allergen. More frequently, though, what may seem like an allergy is actually a food intolerance. Adverse food reaction is the correct terminology, since you cannot distinguish between an allergy and an intolerance. 

The difference is important as intolerances aren’t related to the immune system. For example, ingestion of excessive fat. 

Where you may see the difference is in your dog’s symptoms. 

Typically, skin reactions such as itchy skin and ears are signs of an allergy; diarrhea and vomiting (GI issues) may indicate an intolerance. If you see both types of symptoms, however, an allergy may be to blame.

Your veterinarian can help you sort through the symptoms and pinpoint the cause. 

Dog Food Allergy Symptoms

Signs of food allergies in dogs can include:

  • GI upset
  • Vomiting
  • Diarrhea
  • Excess gas 
  • Weight loss
  • Excessive licking
  • Chronic ear infections
  • Bacterial, fungal or yeast infections
  • Intense itching and scratching that can cause red, irritated-looking skin

Which Breeds Get Dog Food Allergies?

While all breeds, including mixed breed dogs, can develop allergies, certain breeds are over-represented when it comes to developing them. These include:

Often, allergies emerge when dogs are between one and three years of age, but this is not a strict rule.

Protein Allergies

Any dog food ingredient could trigger an adverse reaction, but ONLY proteins can elicit a food allergy.

Among proteins, research shows a beef allergy in dogs occurs most often, followed by dairy and poultry. The immune system may overreact to the presence of the protein, triggering the allergy. A protein intolerance occurs when the digestive system can’t properly break down the ingredient.  

Is Your Dog Allergic to Meat?

Knowing that proteins are the leading cause of dog food allergies and many formulas are animal-based, you may be wondering, “Is my dog allergic to meat?” 

It’s possible they might have a negative reaction to all forms of animal protein, but probably not likely. 

If the animal protein in their current diet is causing problems, you might try other formulas with different meat sources. Some pet owners may also be interested in a vegetarian or vegan diet; just make sure it’s complete and balanced, and properly formulated with essential nutrients for your pet.

What About Grain Allergies?

Grains and gluten get a lot of attention for their alleged negative effects on canine health. Every dog owner should choose what’s best for them, but grains are a healthy source of nutrients and not a significant cause of allergies in dogs. 

If you’re concerned about what seem to be your dog’s grain allergy symptoms, however, contact your veterinarian.

Novel Proteins & Alternative Ingredients

Fortunately, there are many food choices made without ingredients commonly linked to dog food allergies and intolerances.

A novel protein is a protein source that your pet has never consumed previously. Switching your pet to a new protein source may help to improve clinical signs but over-the-counter limited ingredient diets are often cross-contaminated with other protein sources.

If you’re concerned about grains or other ingredients, you can find grain-free options as well as food made without wheat, corn or soy

Diagnosing Dog Food Allergies 

If your dog has GI and skin allergy symptoms, your veterinarian will likely suspect a food allergy over other potential allergies. They might prescribe an elimination diet, which is considered the gold standard in determining if a pet has a food allergy.  

With an elimination diet, you veterinarian can switch your canine’s food to a hydrolyzed formula to see if their condition improves. For a period of at least 4 to 12 weeks, no other food, treats or flavored supplements (like some heartworm and flea prevention chews) can be eaten.   

If the clinical signs subside, then you can re-challenge your pet by steadily introducing other ingredients back into their diet and observing how they react.  

Once you and your veterinarian have identified the source of your dog’s food allergy, you can discuss options that are free of the ingredient that causes the reactions. 

Remember, the right choice for pets with dog food allergy symptoms is the one that provides both relief and nourishment.

Talk through the options with your veterinarian, and be sure to transition between foods gradually, to help your dog successfully make the switch to their new dog food without further upset. 

For more dietary tips from our experts, check out our Pet Expertise page. 

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