How to Identify and Treat Food Allergies

By: Carol Hurst, LVT

Houston, TX

Published December 2016

In our dogs and cats, there are a few different types of allergies: food, inhalant, flea and contact. Allergies (of any kind) are often not black and white. Most pets are allergic to more than one thing.

For food allergies, pets can be allergic to one ingredient or more than one ingredient. The most common sources for allergic responses for pets are beef, dairy, wheat and lamb (as well as chicken in dogs and beef, dairy, fish and chicken in cats).* Food allergies in dogs and cats can manifest as itchiness of the feet, face, inguinal (inside of the back legs), rear, axillary (under the front legs) and ears. It can also manifest as vomiting and diarrhea. Food allergies account for 10 to 20 percent of allergic responses in our dogs and cats.* That is a relatively low number compared to other causes of allergic responses.

Testing can be used to determine the pet’s allergy. This can be helpful when trying to find a specific diet and avoid certain ingredients. Prior to performing any allergy testing on your pet, be sure to have your pet on an appropriate flea control to rule out fleas as a potential itching source. Additionally, have your pet on a topical heartworm control that is not flavored.

To identify the food allergen, veterinarians may recommend pets go on an elimination diet trial or hypoallergenic diet trial. The term “hypoallergenic” is ascribed to a diet that is unlikely to cause a cutaneous[SO1]  [DG2] adverse reaction in a dog or cat. There are two categories for hypoallergenic diets—hydrolyzedundergo chemical breakdown due to reaction with water and novel-proteina protein source that the pet has never eaten before.

Hydrolyzed foods have a protein source (usually chicken) broken down into such small parts that the body does not recognize it as an allergen. There are only a handful of commercial diets available that are considered genuinely hydrolyzed. Alternatively, a novel-protein diet is one that has a primary protein source that is unlikely to cause an allergic reaction. If many pet foods contain beef, chicken and lamb, choosing a food with a different protein source (such as venison) can prove helpful in improving potential food allergies.

A hypoallergenic diet trial is performed for a minimum of 12 weeks. During this time, the pet is fed nothing but the new (ideally, hypoallergenic) formula. This includes no table food, treats and flavored medications. At the end of the 12 weeks, the pet can be assessed for improvement. They can stay on the hypoallergenic diet or move to a novel-protein diet as their maintenance diet.

Alternatively, a veterinarian can recommend an elimination method. With an elimination diet trial, the same 12-week method is prescribed. Instead of providing a commercial hydrolyzed diet, the pet consumes a homemade diet with ingredients that are consistent and controlled. Pets that may not be able to tolerate a commercial hydrolyzed diet can benefit from this method. Any elimination diet trial should only be under the direct supervision of your veterinarian or a veterinary nutritionist as the formulation of ingredients should be specific to continue to meet the nutritional requirements of the pet.

* Percentages and allergen lists taken from Pocket Companion to Small Animal Clinical Nutrition, 4th Edition by Hand, Novotny.

Carol Hurst, LVT, is a graduate of McLennan Community College who lives in Houston, Texas. She works at ABC Animal & Bird Clinic.