What is the recommended first step in diagnosing food allergy in dogs presenting with pruritus?

• A. Elimination diet trial
• B. Skin scrapings
• C. Serum allergy testing
• D. Antibiotic trial

Answer: (A)

Diagnosing a suspected food allergy in a dog with pruritus is approached most effectively by an elimination diet trial. This method tests the dietary trigger directly: you feed a strictly controlled diet with a novel protein or a hydrolyzed protein for about 8–12 weeks, with no other foods, treats, flavored medications, or chews. If itching and dermatitis improve during the trial, it strongly supports a dietary cause. A subsequent controlled re-challenge—reintroducing the previous diet or suspected ingredients—can confirm the culprit by causing a relapse of symptoms.

Other tests don’t address the dietary cause. Skin scrapings look for parasites or infections, serum allergy testing targets environmental or atopic sensitivities rather than food, and an antibiotic trial wouldn’t identify a food-related issue. The elimination diet trial is the most direct, reliable way to determine if food allergy is driving the pruritus.