Elimination Diets for Dogs and Cats

In clinical practice, I’ve often worked with pet owners facing frustrating and persistent problems in their dogs and cats, such as chronic skin issues, ear infections, or gastrointestinal troubles. These symptoms can be caused by many factors, but one of the most common culprits is adverse food reactions, including food allergies and intolerances. One of the most effective tools to diagnose and manage these conditions is the elimination diet.

This month, we’ll explore what elimination diets are, when and why they’re used, the steps involved, and the role they play in reducing medication use.

What Is an Elimination Diet?

An elimination diet is a carefully controlled feeding plan designed to determine whether your pet’s symptoms are related to a specific food ingredient. The diet consists of limited ingredients, including novel proteins and carbohydrates—ingredients your pet hasn’t consumed before—or hydrolyzed protein diets, in which proteins are broken down into molecules too small to trigger an allergic response.

The goal is to eliminate exposure to potential allergens and observe whether symptoms improve. If they do, we can reintroduce favourite foods one at a time, watching closely for the reappearance of symptoms.  This allows us both to round out the diet, and to pinpoint the culprit causing skin or gastrointestinal problems.

When Are Elimination Diets Used?

Elimination diets are commonly used for pets with chronic or recurrent symptoms, such as:

• Skin problems: Persistent itching, rashes, hot spots, or hives
• Ear infections: Recurrent or chronic otitis
• Gastrointestinal issues: Vomiting, diarrhea, or excessive gas
• Unexplained inflammation: Swelling or redness not caused by external factors

These signs often indicate a food allergy or intolerance, and elimination diets help diagnose and manage these conditions.

The Diagnostic and Therapeutic Benefits

Elimination diets serve both diagnostic and therapeutic purposes. Diagnostically, they confirm whether food is contributing to your pet’s symptoms by observing changes when specific ingredients are removed and reintroduced. Therapeutically, elimination diets provide long-term relief by excluding problematic ingredients.

Once the offending allergens are identified, the diet becomes a tailored solution, often resulting in a significant reduction or complete resolution of symptoms.

How to Conduct an Elimination Diet

Selecting the Diet

Your veterinarian will recommend a diet tailored to your pet’s needs. Common options include:

• Novel protein diets: Made with uncommon protein sources like venison, duck, kangaroo, or rabbit, combined with unique carbohydrates like sweet potato or quinoa.
• Hydrolyzed protein diets: Commercial diets from veterinary brands like Hill’s Prescription Diet, Royal Canin, or Purina Pro Plan Veterinary Diets, where proteins are broken into smaller pieces to avoid immune system recognition.
• Homemade diets: These involve cooking a single novel protein and carbohydrate under veterinary guidance to ensure nutritional balance.

Transition Period

To prevent digestive upset, your vet may recommend that you transition your pet to the new diet gradually over 7–10 days. Mix increasing amounts of the new diet with the current food until the old diet is completely replaced.

The Elimination Phase

During this critical phase, which lasts at least 12 weeks, you must feed your pet the elimination diet exclusively. This means no other foods, treats, table scraps, flavored medications, or supplements. Even small exposures to potential allergens can compromise the results.  For this phase, all household members and caretakers for your pet must be aware of the elimination diet, and cooperative with the process.

Monitor and document your pet’s symptoms throughout the trial. Many owners notice improvement in symptoms within 4–6 weeks, but some pets require the full 12 weeks to respond.

The Reintroduction Phase

If your pet’s symptoms improve during the elimination phase, you’ll know that food was contributing to your pet’s problem.  After symptoms have been under control for a few weeks, you will have the opportunity to reintroduce single ingredients one at a time.  This allows you to re-introduce favourites, like peanut butter, or cheese, but it could also help you to identify the offending allergen. Each new ingredient is added one-at-a-time for 2 weeks while monitoring for a return of symptoms.

For example, if your dog’s elimination diet includes duck and sweet potato, you might reintroduce chicken as a single ingredient and observe for itching, vomiting, or other symptoms. If none occur, chicken can be considered safe. If symptoms return, chicken should be excluded permanently.

Long-Term Management

Once the problematic ingredients are identified, you’ll work with your veterinarian to create a balanced, long-term diet that avoids those allergens. This could involve continuing the prescribed novel or hydrolyzed diet or transitioning to a commercial diet free of the specific allergens.

What If Symptoms Reappear?

If your pet’s symptoms return after introducing a new food, stop that ingredient immediately and revert to the elimination diet until symptoms resolve. Once your pet stabilizes, you can proceed with testing other ingredients.

This methodical approach not only identifies allergens but also ensures your pet’s comfort during the process.

Other Treatments Used With Elimination Diets

While elimination diets are the cornerstone of managing food allergies, additional therapies may be used alongside the diet during the diagnostic phase:

• Medications: Corticosteroids, antihistamines, or immunomodulators to control inflammation and itching.
• Topical treatments: Medicated shampoos, sprays, or ointments to soothe skin irritations.
• Supplements: Omega-3 fatty acids to support skin health and reduce inflammation.

As the elimination diet resolves symptoms, reliance on these medications to support your pet’s health and comfort often decreases, minimizing potential side effects and improving your pet’s overall well-being.

The Advantages of Elimination Diets

Elimination diets offer a natural and targeted approach to managing food allergies and intolerances, reducing or eliminating the need for long-term medications. They address the root cause of the problem rather than masking symptoms, resulting in a healthier, happier pet.

Conclusion

Elimination diets are a powerful tool in veterinary medicine for diagnosing and managing food allergies and intolerances in dogs and cats. By systematically removing and reintroducing foods, we can identify and exclude problem ingredients, providing relief from frustrating symptoms.

If you think your pet might benefit from an elimination diet, consult your veterinarian to develop a tailored plan that ensures your pet’s health and well-being.