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Nutrition for Dogs With Food Allergies

Dogs with food allergies can experience skin and digestive issues. To help a dog avoid the antigen that triggers their allergy, a vet may recommend a change in diet.
Brown and white Jack Russell being held by two people


A food allergy occurs when a dog’s immune system confuses something in its diet, typically a protein, for a harmful invader – like bacteria or a virus. 


The resulting immune system response can cause a dog to experience a range of signs, including inflamed skin, itchiness, and diarrhea. 

To reduce the likelihood of a response, a vet may recommend a new diet, however, they’ll usually try to determine the underlying cause of the reaction first. 

How Is a Food Allergy Diagnosed in Dogs?

A dog’s allergy may be caused by their diet or by something within their environment such as dust or pollen – a condition also known as atopy. 

A vet will often recommend an elimination diet trial to identify whether food or atopy is the cause of the dog’s allergic response and to determine the treatment and management required. 

If you’d like to learn more about atopy, see our article: Are My Dog’s Allergies Caused by Their Food or Environment? 


What Is an Elimination Diet Trial?

Elimination diet trials involve feeding a dog a restricted diet where proteins have been broken down to such an extent they no longer create an allergic reaction.

An elimination diet trial begins by slowly transitioning a dog from its current food onto a new diet. Usually, it is an extensively hydrolyzed protein diet, specially formulated for adult dogs with severe adverse food reactions. 

Unlike typical pet foods which have large intact proteins, many veterinary exclusive diets contain hydrolyzed protein, which means the protein has been cut into small pieces at a molecular level.

Because a dog’s immune system is less likely to identify these tiny proteins as a threat, the chance of an allergic reaction is reduced. These diets may contain limited ingredients to minimize the number of potential antigens.

If a dog begins to show signs of improvement after being fed the new food for a couple of weeks, a vet will reintroduce suspected ingredients to see if they provoke an immune system response. If they do, the vet will usually move the dog onto a tailored diet containing an alternative source of protein.

To achieve an accurate diagnosis, the dog owner has to be very careful about how they store and handle the new food during the trial period. They must also make sure that everything from their previous diet is eliminated – including treats, chews, and leftovers.

Every family member will need to be disciplined about what they feed the dog throughout the trial period too. Identifying what causes the immune system response is a vital step in aiding a dog with food allergies. 

How Can Nutrition Support Dogs With Food Allergies?

If food sensitivity is diagnosed, a vet may recommend a new diet to help limit exposure to allergy-triggering molecules and reduce the likelihood of them experiencing the associated health issues. 

Based on the immune system trigger and the dog’s health condition, there are several dog food allergy management options a vet may suggest, including a novel protein diet, a hydrolyzed protein diet, or a vegetarian diet if the proteins in it are novel. 

These diets contain either a different source of protein to their current diet or the protein molecules will have been cut into small pieces. 

Typically, they’re manufactured under very strict conditions in controlled facilities to prevent cross-contamination with other food sources that can cause allergic responses. 

Tailored diets, like those from Royal Canin, are specially formulated with a blend of nutrients to:

  • Aid digestive health by regulating intestinal transit.
  • Support the skin’s natural protective barrier.
  • Support digestive flora.
  • Aid cellular health with their complex blend of antioxidants.

Illustration of vet and suggested nutrition

Novel Protein Diets 

These diets contain sources of protein that a dog may not have been previously exposed to – like duck, fish, rabbit, or venison. Because these proteins are potentially unfamiliar to the immune system, they’re less likely to trigger a reaction.

Veterinary exclusive novel protein diets are different from those more commonly found in retail pet foods as they contain specific nutrients to help manage the health issues that arise through food allergies.

However, protein sources that used to be uncommon in dog food are being found in more dog foods sold at pet food and grocery stores. This makes finding a novel protein, one that the dog has not been exposed to, much harder than in years past. Some of the novel protein sources also compete with the human food chain making them increasingly difficult to source in a sustainable manner. 

A variety of wet and dry novel protein diets are available, with a choice of protein sources. Some are lower in calories while others support joint health.

Hydrolyzed Protein Diets

We’ve already discussed how hydrolyzed diets contain protein that’s been broken down at a molecular level to reduce the chances of an immune system reaction. However, these diets support dogs with digestive health issues in other ways too. 

They typically contain a single source of starch and protein and are enriched with both soluble and insoluble fibers to aid digestion. 

To encourage eating in dogs with reduced appetites, hydrolyzed protein diets are designed to be very palatable and often come in both wet and dry varieties. 

Options to support small dogs, overweight dogs, and those prone to urinary stones are available.

Hydrolyzed diets are often recommended for dogs with unknown or broad diet histories to avoid novel proteins they might already have been exposed to.

Vegetarian Diets for Dogs

If a dog is sensitive to animal protein, a vet may recommend a diet that’s sourced purely from vegetarian protein. 

Like novel protein diets, vegetarian diets are less likely to trigger an allergic response. 

Illustration of vegetables

How Long Does a Dog Need To Remain on a Tailored Diet?

It depends on the cause of the dog’s food allergy. If the condition is permanent it may be necessary to keep them on a tailored diet for the rest of their life or until other health conditions prompt a change in diet. Your vet will be able to offer you guidance for your dog. 

What Should I Feed a Dog With Food Allergies? 

Diagnosing a food allergy is challenging and a vet will need to decide which dog food allergy management option is suitable based on the results of their elimination diet trial, clinical signs, and health condition. 

What if a Change in Diet Doesn't Work?

Dogs on elimination diet trials usually begin to show signs of improvement within 1 to 3 weeks for digestive issues and within 12 weeks for dermatological signs. 

If a dog continues to show signs after that time, or the trial fails to identify a food allergy, a vet may decide to conduct further diagnostic tests and investigate other possible causes. 

To learn more, visit our section on environmental allergies.

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