How is food allergy diagnosed?

The only effective way for your veterinarian to diagnose a food allergy is to put your pet on a “hypoallergenic” or “exclusion” diet for a minimum of 8–12 weeks. Such a diet contains ingredients to which the animal has not been exposed in the past. Because the source of protein causes most allergic reactions, exclusion diets use proteins—often venison, fish or duck—that are normally not found in regular pet food. An exclusion diet may comprise home-prepared food or prescription commercial hypoallergenic products.

If your pet has a food allergy, there should be a significant reduction in the symptoms after the recommended period on the exclusion diet. To identify all the food allergens, your veterinarian will recommend adding a single protein back into the diet every 1–2 weeks, while watching for a recurrence, or worsening, of symptoms. If this happens, the veterinarian will recommend removing the offending ingredient from the diet.