Some cats occasionally have food allergies. An ingredient in their diet, usually part of the protein content, disagrees with them and causes itching of the skin or diarrhea. Food allergies can severely harm your cat's quality of life. As a cat owner, you need to manage your cat's diet, discovering which ingredient is causing the problem and eliminating it. Take the time, together with your vet, to find the cause of your cat's allergy and feed her an appropriate diet so she can live a healthier and happier life.
What is a food allergy?
Food allergies are estimated to cause only up to 1% of all skin problems in cats. However, other allergic skin problems -- for example, allergy to fleabites -- are more common. Food allergies may also cause gastrointestinal problems, such as vomiting or diarrhea. Animals that have both itching of the skin and gastrointestinal problems are likely to have food allergies.
It is not known exactly how a food ingredient in the diet results in the symptoms of a food allergy. It may be that abnormal amounts or types of protein particles from food are absorbed into the bloodstream and so, antibodies and inflammatory chemicals are released from cells of the digestive tract and skin -- the skin and digestive tract then become sensitive to food containing that particular protein ingredient.
Sensitivity reactions -- itching, vomiting, or diarrhea -- may occur within minutes, within hours, or even several days later. The offending ingredient may not be a new one in the diet. Allergies can develop to foods your pet has been eating for years -- and the allergy may develop suddenly. Once it has developed, the allergy may last a lifetime, so foods containing that ingredient will have to be permanently eliminated from your pet's diet.
Which foods cause food allergies?
Any food ingredient that your cat has previously eaten can cause allergic reactions, but the protein part of the food is the most likely culprit. Beef, eggs, fish, wheat gluten, and lamb commonly cause reactions. Some pets develop diarrhea when fed milk, but this is, probably, an intolerance rather than a true allergy.
Diagnosing food allergies
Skin irritation and scratching are also caused by things other than food allergies. Consider all possible causes of your cat's symptoms -- and if her damaged skin is making your cat irritable or miserable, talk to your veterinarian. She or he may prescribe anti-inflammatory drugs until the "itch-scratch" cycle is broken.
The elimination diet
Your veterinarian may put your cat on an elimination diet. Because the offending food is usually one your cat has eaten before, your veterinarian will ask you for a list of all the foods in your cat's diet -- including treats, bones, table scraps, and other snacks! With this list, he or she will prescribe a diet for your pet made up of foods she has not eaten before and which are unlikely to cause allergic reactions, such as a selected protein diet.
The elimination diet constitutes a diagnostic procedure. Feed your cat only the elimination diet for the prescribed time. Don't give her any snacks or supplements -- even tiny amounts of other foods can ruin this diagnostic procedure. Your cat may have to stay on the diet for up to 10 weeks: it often takes that long for the itching caused by the allergy to completely disappear. Your cat may have diarrhea or other gastrointestinal problems -- but these usually improve within a few days.
After the diet has reduced your cat's symptoms, your veterinarian may recommend that you slowly and carefully re-introduce different protein sources back into your cat's diet. In this way, you can determine which proteins she is allergic to. Introduce potentially irritating foods back into the diet step by step -- one new food ingredient per week. If the itching or diarrhea recurs, you've probably discovered the offending food.
Looking after allergic pets
If your cat has been diagnosed as having a food allergy, remove the offending food from his diet. Replace his old diet with a new one that does not trigger his allergic responses. Your veterinarian can recommend special diets for pets with allergies. To help identify the source of the food allergy, and to help keep your cat healthy afterward, consider these simple guidelines.