The classical canine food allergy lesion distribution includes signs of facial itching, foot or limb chewing, belly itching, and recurrent ear infections.

In cats, food allergy usually produces scabs and other signs of itching around the face or neck.

(Only some of the captioned signs are usually present in a given animal, not necessarily all.)

Your Pet's Itchy Skin

Itchy skin in the small animal is often more than just a minor annoyance. Red, oozing bald patches; rashes; and large expanses of hair loss are unfortunate markers of very real discomfort for which a cause should be sought and dealt with.

The food allergy is one of the itchiest conditions known to cats and dogs. Animals eat a variety of processed food proteins, fillers, and colorings that are further processed inside their bodies. Proteins may be combined or changed into substances recognized by the immune system as foreign invaders to be attacked. The resulting inflammation may target the gastrointestinal (GI) tract or other organ systems, but in dogs and cats it is the skin that most often suffers from this immunologic activity.

Many people erroneously assume itching due to food allergy requires a recent diet change of some sort. In fact, the opposite is true.

Food allergy requires time to develop; most animals have been eating the offending food for years with no trouble.

What Kind of Allergy?

Sarcoptic mange and inhalant allergy (also known as atopy) are the two conditions which must be distinguished from food allergy as the treatment approach to each is markedly different. Much time and money can be wasted pursuing the wrong problem.

Please consider the following clues that contribute to pointing us towards the food allergy as a diagnosis. Your pet demonstrates:

• Your pet has been treated for sarcoptic mange without any positive change.
• Your pet's itchiness is not and has never been a seasonal problem.
• Your pet has responded poorly or only partially to cortisone-type medications.
• Your pet has had a skin biopsy demonstrating changes often associated with allergy or, more specifically, food allergy.
• A lesion distribution pattern that is common for food allergy (see illustration above).
• Your pet did not have skin issues before age 5 or 6.

Any of the above findings or observations warrant pursuit of food allergy.

Note that three of the above four criteria relate to what you, the owner, observe at home. Trouble results when the veterinarian must speak to different family members about the pet and there is disagreement in their observation of the pet at home. It is best to have one person, preferably the one who has the most contact with the pet, be the spokesperson and make the relevant judgments.

The Flea Factor

Some animals have many allergies. It would not be particularly unusual for an animal with a food or inhalant allergy

Flea

Ensure immaculate flea control for any itchy pet!

See more information on flea biology and flea control.

How to Deal with the Food Allergy Suspect: The Hypoallergenic Diet Trial

The Basic Principle

To determine whether or not a food allergy or intolerance is causing the skin problem, a hypoallergenic diet is fed for a set period of time. If the pet recovers, the original diet is fed for up to two weeks to see if itching resumes. If we see recovery with the test diet and itch with the original diet, then food allergy is diagnosed and the pet is returned to either the test diet or another appropriate commercial food indefinitely.

Date Published: 1/1/2001
Date Reviewed/Revised: 4/11/2011