Allergic Skin Disease

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Allergic Skin Disease

Spring is finally here, which means allergy season for many of us. Like people, cats can have allergies too. Cats are most commonly allergic to flea bites (Flea Allergy), something in their food (Food Allergy) and things in their environment like pollen, dust mites, and grasses (Atopy). Cats can have one or more of these allergies which can make diagnosing the cause of their allergies difficult; however, we often treat allergies in cats the same way regardless of the underlying cause. Allergies cannot be cured, but with a little time and effort your veterinarian can often get your cat feeling better and more comfortable. If you have any concerns that your cat may have allergies, a visit to our veterinary clinic is needed.

It’s important to rule out other causes of itchy skin, like ringworm and parasites, before treating allergies.

Flea Allergy

Flea allergies are the most common cause of allergic skin disease in cats and dogs. Even one flea bite can cause a severe allergic reaction and since cats are fastidious groomers, the fleas can often be hard to detect with a flea comb. A common misconception is that fleas are only an issue in warmer months; however, fleas can survive indoors year round and our winters can be mild at times. Fleas can be a huge problem year round, and we recommend all cats, not just allergic cats, receive year round flea protection with Revolution. Fleas also carry diseases that our cats can get and give to us, like tapeworms and cat scratch fever (Bartonella).

Signs of fleas on your cat may include itchiness, hair loss, scabs, or visible fleas or flea dirt on the fur. Treatment includes topical therapy for all the pets in the house and good environmental control. Do not use any flea products without consulting your veterinarian first, as some flea products can be toxic to cats when applied. All cats with skin lesions should receive flea control, even if we suspect they may have Atopy or Food Allergies. Any pet with fleas should also be treated for tapeworms.

Your veterinarian will help you with the right treatment plan for your cat and your home.


Atopy is allergies related to things in the air, like dust, mold, pollen, which are usually harmless to most pets except when they have an inherited sensitivity to the allergens. The sensitive cats will start to show signs of hair loss, itchiness, scabs, ulcerations and plaques. Since cats spend a lot of their time indoors, we typically don’t associate seasonality with atopy, but you may see this in certain cases. The average age of onset of symptoms is 1-3 years of age, but a cat of any age can be affected. Diagnosis is made based on history, symptoms and allergy testing.

There are two ways to test for allergies, a blood test or intradermal skin testing. The tests aren’t perfect, and we often get false negatives and false positives with this testing; however, it can be a good place to start when trying to remove allergens from the environment or when we want to give desensitization injections.

Treatment is tailored to each cat, as your cat may respond differently from another cat. We often use food, steroids, antihistamines, essential fatty acids, topical treatments, allergy shots or a combination of these treatments until we find what works best for you and your cat. In addition, keeping your cat indoors, turning on the air conditioning, using an air filtration system, cleaning with a HEPA filter vacuum and eliminating carpet from the house can help reduce the allergen load.

Food Allergies

Cats can be allergic to a protein or carbohydrate source in their food. Common ingredients in most cat foods, like chicken, beef, fish, wheat, barley and soy, can cause itchy skin or gastrointestinal signs (vomiting and/or diarrhea). To diagnosis food allergies we feed a novel protein diet or hydrolyzed protein diet exclusively for 8-12 weeks.

A novel protein diet contains proteins and carbohydrates not found in the typical cat foods. Most diets contain rabbit, venison, or duck and use green peas as the carbohydrate source. Since most cats never ate these proteins or carbohydrates before, they shouldn’t have an allergic reaction to the food; however, there is some cross reactivity to the proteins and some cats won’t respond to this type of diet. Hydrolyzed protein diets, like Royal Canin HP or Science Diet Z/D, break down the proteins to small molecules not recognized by the body as an allergen. The veterinarians and technicians at our veterinary clinic can help you find the right diet for your cat.

At the end of the food trail the previous diet is reintroduced and if the allergy symptoms return, a food allergy is confirmed. Most clients are happy with how well their cat is doing on the new diet that many don’t do the food challenge.
More information can be found here:

CatHospital_C – Animated

422 East Baltimore Avenue • Media, PA 19063
Phone: 610-627-2287 | Fax: 610-627-2289 | Email:

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