Pet Health Information

FOOD ALLERGY

This is an uncommon disease caused by an allergic reaction to various ingredients contained in a pet's diet. The major signs of food allergies in dogs and cats are non-seasonal pruritis (itching) and/or diarrhea. Animals of any age, breed or sex may be affected. Although the allergy may result from a recent change in diet, 70% of affected animals have been eating the offending diet for over 2 years. Ingredients reported to have caused allergic reactions in dogs and cats include protein sources (beef, poultry and eggs), dairy products, carbohydrate sources (wheat, corn and oatmeal), and additives such as colorings, flavorings and preservatives.

The major complaint from the owner is pruritis. A variety of skin lesions may be seen. In dogs the areas of the body often affected are the ears, feet, face, inner thigh and axillary (armpit) regions. The skin may be simply inflamed from scratching or there may be scale, hair loss, pustules and scabs from continued irritation. In cats the pattern of skin lesions commonly involves the neck, face and ears. There may be redness, hair loss, scabs from scratching, raised plaques or a generalized distribution of tiny bumps in the skin (miliary dermatitis).

There are a number of skin diseases, which appear with signs similar to those seen with food allergies. Flea bite allergy, atopic disease (allergy to environmental substances such as pollens or plants) or skin parasites can all cause similar signs. The diagnosis of a food allergy is ultimately made by feeding the animal a restricted diet of protein and carbohydrates that the animal has never eaten before. This diet must be fed for a period of 6-8 weeks while the pet is monitored for decrease in pruritis. The diagnosis may be confirmed by feeding the animal its normal diet after this trial period and observing the pruritis to worsen.

A commonly used hypoallergenic diet is a mixture of lamb and rice. However, due to the popularity of this diet, many animals have been exposed to it so it is no longer particularly effective as a restricted diet. There are a wide variety of prescription hypoallergenic diets available from manufacturers such as: Purina, Royal Canin, Hill’s Prescription Diets, and a few others.

It is essential that only the restricted diet and water be fed to your pet during the food trial. There may be no table scraps, rawhide chews, or even chewable heartworm preventive during this period. Any "treat" may invalidate the whole diet trial process.

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