Last month I attended the North American Veterinary Conference in Orlando, FL.  The conference hosted over 14,000 attendees including veterinarians, veterinary technicians, practice managers, staff members, academicians, vet industry personnel, and guests.  There were great continuing education seminars and the largest veterinary industry trade show in the world.  I always enjoy these conferences because you never know what you will learn between treatments and procedures, drugs and equipment, and research and future trends.

One of the seminars I attended covered feline food allergies causing dermatitis.  Food allergy is a term used to describe an adverse reaction to a food, but adverse reactions also include food intolerances which are different.  Allergies involve an immune response by the body.

A food intolerance typically occurs as a result of a recent food change.  It can be an immediate reaction.  Food intolerances are due to either a lack of digestion of an item or a lack of absorption.  A food allergy (or hypersensitivity) develops as a result of a longer term exposure to a food, where an immune response has occurred.  Food allergies can cause dermatologic or gastrointestinal problems.

Diagnostic testing for allergens includes intradermal skin testing and blood tests that look for specific antibodies to the allergens.  Unfortunately, all of these tests are considered unreliable as a method for confirming food allergy in animals with skin disease.  The best way to confirm a food allergy is through an elimination diet for 4-8 weeks.

Studies have shown that the most common food allergens in cats are fish, dairy, and beef.  An elimination diet is a tricky thing, especially if you have a cat that goes outside.  You need to consider the food that you are feeding, any snacks, supplements, or treats, chewable medications, table food, and what your cat could be eating if he hunts or visits the neighbors.  A new, unique protein source is required in an elimination trial.  There are several veterinary therapeutic diets designed with one special protein source.  You may try one or two flavors initially to see what your cat prefers, but then you need to stick with one protein.  A hypoallergenic diet only works if the animal has never been exposed to that type of protein before.  To be successful, you cannot cheat with even one treat or snack from your dinner plate.

The problem with over the counter limited protein diets is that the labels do not always show all of the ingredients. One study that was referred to in the seminar found that 75% of over the counter canine limited protein diets tested positively for other proteins such as soy, beef, and poultry.  A common reason this occurs is because the pet food is manufactured at a plant where regular diets are made and equipment causes cross contamination of proteins.

It is ideal to choose a veterinary therapeutic novel protein diet or make a homemade diet when conducting an elimination diet trial.  It is difficult to create a homemade diet that includes all of the nutritional requirements for a cat.  Lamb baby food or rabbit are examples of protein sources used in homemade diets but without supplementation they are often deficient in calcium, essential amino acids, fatty acids, and vitamins.

In addition to unique protein diets, there are therapeutic hydrolyzed protein diets.  Hydrolyzed proteins have been broken down to such small molecules that they do not trigger an immune response.  These diets have shown to be effective in eliminating skin and GI problems in food allergic patients.

If an animal’s skin or digestive problems improve after a strict, hypoallergenic diet, most owners choose to continue the diet.  To know definitively if a certain protein was causing problems, you would need to re-challenge the pet with this protein.

We are fortunate that we have therapeutic diets in veterinary medicine to help us treat our patients.  Given the choice, if a cat’s disease could be controlled with diet versus oral medication, an owner is going to choose the diet.  Making the diet switch may seem initially complicated but it is definitely worth a try to see if it will be an effective therapy.

Written by Dr. Wexler-Mitchell of The Cat Care Clinic in Orange, CA
Copyright © 2011 The Cat Care Clinic