Understanding Food Allergies and Sensitivities in Dogs

Written by: 

Dr. Danielle Conway, DVM ACVIM Nutrition Board Eligible, CVA, VSMT  

Nutrition board-eligible veterinarian with extensive experience in integrative medicine and nutrition.  

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Does your dog have a food sensitivity, food allergy, or just a sensitive GI tract? Understanding the differences and how to manage these conditions is crucial for your pet’s health. Dogs, like people, can have various gastrointestinal issues caused by different factors, and knowing how to identify and address them can make a significant difference in their well-being.

Woman giving her dog a treat

Food Allergy vs. Food Sensitivity in Dogs

What is a Food Allergy?

Food allergies in dogs are relatively uncommon and involve an overactive immune response to certain proteins in their diet. These allergies develop as a result of repeated exposure to specific proteins, leading to chronic inflammation and various symptoms.

How Food Allergies Develop

  1. Sensitization Phase: The dog's immune system first encounters a specific protein found in common ingredients such as beef, chicken, dairy, or grains. The immune system mistakenly identifies this protein as harmful.
  2. Immune Response Activation: Upon repeated exposure, the immune system becomes sensitized and produces antibodies against the protein.
  3. Histamine Release: When the sensitized dog ingests the allergenic protein again, antibodies trigger immune cells to release histamines and other inflammatory chemicals.
  4. Allergic Reaction: This release causes symptoms like itching, redness, skin rashes, ear infections, and digestive issues.
  5. Chronic Inflammation: Continued exposure leads to chronic inflammation, significantly impacting the dog's health.

Understanding Food Sensitivities

Food sensitivities, more common than allergies, do not involve the same immune system activation. They can present similar symptoms but are generally easier to manage. Dogs with food sensitivities often react to certain ingredients without the immune response associated with allergies.

How the Body “Remembers” Allergens

When the intestines become inflamed, larger pieces of partially digested food can pass through the intestinal lining, triggering an immune response. This inflammation causes clinical signs such as vomiting, diarrhea, skin itching, hot spots, ear infections, and weight loss. Proteins, being large, trigger this response more than carbohydrates or fats.

Diagnosing Food Allergies and Sensitivities in Dogs

Initial Steps:

  1. Dermatology Workup: If your dog has itchy skin, a dermatology workup should be done to rule out common causes like parasites.
  2. Novel Protein Diet Trial: The least invasive and reliable test for food allergies and sensitivities is a strict novel protein diet trial for 6-12 weeks. This involves feeding a protein your pet hasn't been exposed to before.

Diet Trial Process:

  • Strict Adherence: Ensure no other protein sources are introduced during the trial.
  • Evaluation: If symptoms persist after 12 weeks, the issue might not be a food sensitivity. Consider consulting a veterinary dermatologist or internist.

Treating Food Allergies and Sensitivities in Dogs

Main Strategy:

  • Decrease Inflammation: Feeding a novel protein diet (such as fish, duck, or bison) helps reduce inflammation because the body does not recognize the new protein. Additional supplements or medications might be needed if inflammation is extensive.

Skin-Responsive Enteropathies

Environmental allergies are more common than food allergies in dogs. If symptoms persist after a diet trial, environmental factors should be considered. Dogs with food-responsive dermatopathia will show improvement during the trial if food is the cause.

Food Allergy vs. Sensitivity: Key Differences

  • Immune System Activation: A true food allergy involves immune system activation, requiring a prescription diet to avoid cross-contamination.
  • Sensitivity Management: Over-the-counter diets might be sufficient for managing food sensitivities, as they don’t involve the same immune response.


What are common symptoms of food allergies in dogs? Common symptoms include itching, skin rashes, ear infections, vomiting, and diarrhea.

How long does a novel protein diet trial take? A strict diet trial typically lasts 6 weeks for gastrointestinal symptoms and 12 weeks for skin symptoms.

Can dogs outgrow food allergies or sensitivities? Some dogs may develop transient sensitivities that resolve once their GI tract heals.

What should I do if my dog shows symptoms of a food allergy? Consult with your veterinarian for a proper diagnosis and consider a novel protein diet trial.

Are blood-based food allergy tests reliable? No, blood-based food allergy tests are generally unreliable.

How can I ensure my dog’s diet trial is effective? Strictly follow the diet trial guidelines and avoid introducing any other protein sources.

For more detailed information and personalized advice, consult with your veterinarian or visit Dr. Conway’s website to schedule a consultation.

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