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Food Allergy

Historical Clues

Historical clues may increase the likelihood of food allergy:

  • Age of onset - Food allergy can develop at any age. If pruritus starts at less than 1 year of age or greater than 5-6 years of age, then food allergy is more likely than atopy.
  • The sites of pruritus can mimic the atopy distribution of facial and pedal pruritus; however, ventral abdominal pruritus, perianal pruritus, and otitis are common with food allergy.

Diagnostic approach:

The six most common food allergens are beef, dairy, chicken, corn, soy, and wheat.

A strict food trial is the gold standard for diagnosis, but it can be difficult to obtain owner compliance.

Options include a prescription novel protein or hydrolyzed protein diet or a home-cooked novel protein diet.

No single diet is perfect for all patients, and some patients require more than one food trial.

To formulate a home-cooked diet, please contact the UT Nutrition Service at 865-974-8387.

Remember to eliminate all flavored medications, animal-based medications like glucosamine, toothpaste, flavored toys like Nylabones and rawhides, treats, and all other human and animal foods.

The food trial should last a minimum of 6-8 weeks. Do not assess the patient's response to the food trial until all skin infections are cleared.

If a strict food trial is impossible for the owner, then consider avoiding beef, dairy, chicken, corn, soy, and wheat by looking for an over the counter diet that lacks these ingredients. The owners must read the ingredient list carefully. One option for this type of modified food trial is a fish-based diet such as Purina ProPlan Sensitive Skin and Stomach Formula. If this modified trial fails, then a strict food trial using a prescription or home-cooked diet is needed.

If the patient improves with the food trial, the diagnosis can be confirmed with a food challenge if the owner is interested. Options for a food challenge include feeding the previous diet or adding in treats. Only one diet change should be made at a time, and each change should be done at two week intervals.

If pruritus flares with the food challenge, then food allergy is confirmed. Pruritus usually flares within 1-2 days of the food addition, but it can take up to two weeks for some patients to flare.


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