Dr. Louis N. Gotthelf
Montgomery Pet Skin and Ear Clinic
Food allergies are the third most common type of allergy in cats (behind flea allergy and environmental allergy or atopy). This is caused by an allergic reaction to one or more ingredients in the cat's food. The most common causes of food allergies are fish, beef, chicken, eggs and wheat. Cats become allergic to foods they have eaten for a long period of time (usually two years or more). There is no breed, sex or age predilection. Cats with other allergies (such as atopic dermatitis) may be at greater risk of developing food allergies. There appears to be a genetic component.
What are the symptoms of food allergies in cats?
Symptoms of food allergies occur over a period of months. The most common signs of food allergy include:
- Non seasonal itching, especially on the front half of the body, head, face, ears and neck.
- Otitis externa - Itching and scratching can lead to inflammation and sometimes infection
of the ears.
- Excessive licking of the affected skin.
- Affected areas of the skin may develop papules (small, fluid filled bumps).
- Hair loss(due to excessive scratching, grooming etc).
- Some food allergic cats will also have chronic vomiting and/or diarrhea.
Hair loss and itching of the skin between the eyes and the ears are
typical of food allergy symptoms in cats.
Diagnosis of food allergies in cats:
There is no blood test to diagnose food allergies!!! We will need to rule out other common disorders which have similar symptoms (such as flea allergy dermatitis, inhalant allergy, ringworm, mange). Once this has been done, we will place your cat on a food elimination trial. This usually lasts between 8-12 weeks. During this time, you must not give your cat any other foods, vitamins, minerals or chewable medications apart from the prescribed diet. If any other foods or vitamins are given during this trial it will invalidate the results. If the allergy clears up after the specified time then a food allergy is the likely cause. The diet given to your cat during the trial will be a food the cat has never had before such as rabbit, duck or venison. The diet may also be home made or a special 'prescription' diet.
Recent advances have lead to the creation of hypoallergenic diets containing "hydrolyzed protein" which involves breaking down the protein into individual clumps of amino acids, called polypeptides, which are too small for the immune system to detect (and react to). The nutritional value of the protein is the same as the whole protein. At Animal Hospital of Montgomery we recommend Hills z/d diet, a complete and balanced diet used to help diagnose food allergy. Cat's love the flavor so it is easy for you to do an elimination diet food allergy test at home.
After the food trial, you may be asked to 'challenge' your cat by re-introducing your cat to his usual diet to see if the allergy returns. Of course, Hill's z/d is complete and balanced, so it can be fed as the cat's regular diet. Many owners of cats with food allergies choose to keep their cats on z/d diet, which is perfectly fine.
Treatment of food allergies:
- Avoiding the food which caused the allergies is the best method of treatment. This may either be a home made diet using no meats or dairy, novel ingredients (such as rabbit) or the use of commercial hypoallergenic diet. If you are feeding a home made diet it is important to ensure that your cat is receiving the correct nutrients in the diet. A vitamin/mineral supplement may be added.
- Corticosteroids or cyclosporine may be prescribed to control itching. Unfortunately, not
all cats will respond to this treatment.
- Antihistamines may control the itching in some cats.
- Antibiotics may be required to treat skin infections caused by itching.
If you have decided to feed your cat a home made diet, you may choose at times to introduce a new meat and see how your cat reacts to it. For example, you have your cat on a diet of duck and the allergies go away, introduce beef and see how he reacts. If there are no signs of allergies over a few weeks then you know you can feed him beef; then introduce chicken and watch for signs of allergies returning etc. This way, you can slowly increase the types of food your cat can eat.
If there is not a response to the foood trial, then there may be other reasons for your cat's skin issues. It could be allergic to something else or it could have a bacterial or fungal (ringworm) infection.
Occasionally new food allergies develop over time, if this happens then it will be necessary to reevaluate the new diet.