Food Allergy in Cats
Food allergy is an uncommon problem in cats and it can start at any age. A change in diet is not necessary for development of food allergy. About 70 percent of affected pets develop allergies to food ingredients that they have been fed for a long time, usually more than two years. In fact, if your cat has an immediate adverse reaction to a new food, it is probably not an allergic reaction, because it takes more than one exposure to produce an allergic reaction. Food ingredients most commonly responsible for allergies are beef, chicken, fish, eggs and milk. The tendency to develop allergies is genetically determined. Cats with other allergies like inhalant allergies or atopy may be at increased risk for developing a food allergy.
The clinical symptoms of food allergy resemble those of other types of allergies. These two disorders may have the same clinical symptoms and the same distribution of itchiness or pruritus over the cat’s body. In some cases, it is impossible to differentiate between inhalant allergy and food allergy by clinical appearance alone.
Food allergy should be ruled out first because it is the easier of the two disorders to control by eliminating the offending food ingredient from the cat’s diet. Food allergy is ruled out by feeding a diet consisting solely of food ingredients to which the animal has not been previously exposed – an elimination food trial. This trial should be performed before considering expensive tests for other types of allergies.
What to Watch For
- Itchy (pruritic) skin, especially around the face, paws and ears
- Bad skin odor
- Excessive scaling
- Red bumps or papules
- Ear infections
- Self-inflicted skin trauma resulting from severe itching
- Diarrhea and vomiting, although most cats with food allergy only develop skin problems
Diagnosis of Food Allergy in Cats
Diagnostic tests are needed to recognize food allergy and exclude other diseases that may cause similar symptoms. Tests may include:
- A complete medical history and physical examination. Your veterinarian will examine the skin closely and inquire about your cat’s dietary history. However, most animals that develop food allergy have not had a recent change in diet and have been eating the same food for a long period of time.
- An elimination food trial. This test consists of identifying a diet that contains ingredients to which the pet has never been exposed and strict feeding of this food alone for 8 to 12 weeks. Food allergy is considered a possibility if the itchiness and scratching subside and your cat does not develop relapsing skin or ear infections during the food trial.
Treatment of Food Allergy in Cats
Treatment for food allergy may include one or more of the following:
- Avoidance of the offending food or food ingredient
- Antihistamines to decrease the itching
- Treatment of secondary bacterial or yeast infections
New food allergies can develop over time. If your cat was diagnosed previously with food allergy and has been well controlled with a special diet but once again is showing signs of allergic skin disease, he may have developed a new allergy. Under these circumstances, consult your veterinarian to determine whether a new allergy has developed or whether another disease is present.
Another elimination food trial may be necessary to make this distinction. Patience and determination are important for the success of an elimination food trial. You and your family must be strict and be certain that no one “breaks” the food trial by giving the cat treats or table scraps. Strict compliance with the trial is essential for proper interpretation of the results. This means no treats, flavored medications or flavored vitamins during the trial.
A genetic predisposition seems to exist for food allergy. Based on their genetic constitution, some animals seem to be predisposed to development of food allergy. However, since the cause of food allergy is unknown, the disorder cannot be prevented.
In-depth Information on Food Allergy in Cats
The term food allergy often is used to describe any adverse reaction to foods. Some reactions are mediated by the immune system (true allergy) whereas others are not (food intolerance). Food intolerance and true allergy cannot be reliably differentiated on a clinical basis, and this difficulty explains why a variety of clinical signs are attributed to what has broadly been called food allergy.
Barriers in the gastrointestinal tract prevent adverse responses to ingested food in most individuals. These barriers include both physiologic and immunologic protective mechanisms. Abnormalities in the gastrointestinal defense mechanisms (mucosal barrier failure with increased antigen absorption, defective immunoregulation) may predispose your cat to the development of food allergies. Which of these mechanisms is important in the pathogenesis of food allergies in cats presently is unknown.