Photo by Dr. Teri Ann Oursler

Coping with an itchy cat can be an extremely frustrating experience for you, the pet owner, and can truly test the limits of the human-animal bond.  Persistent scratching and chewing by the pet can also result in open wounds to the skin and pain to your cat.  The following information is intended to help provide pet owners with a basic understanding of the most common underlying causes of itching (pruritus) and allergies in cats.

Common Causes of Chronic Itching

Itching in cats involves not only scratching but also chewing, licking, and rubbing. The common causes of itching in cats are external parasites such as fleas, allergies, and a type of fungal infection called ringworm.

Although medications are available to decrease itching temporarily, it's best to find out the cause of your cat's itching. Otherwise, the itching will return as soon as the medication is stopped. Especially when used over time, some medications like steroids can result in health problems.

What Are Allergies?

Allergies are a common cause of skin conditions in cats. People with allergies usually have hay fever (watery eyes, runny nose, and sneezing) or asthma. Although cats with asthma can be allergic, most cats with allergies lick or chew their fur and scratch their skin.

Major Allergy Types in Cats

Flea Allergy
Flea allergic dermatitis is the most common skin disease in cats.  For the flea allergic patient, 100% flea control is essential for remaining symptom-free. 

“But doctor, I never see fleas on my pet.”  You may not see them, but that doesn’t mean they aren’t there!  Flea allergy is caused by the flea’s saliva, and it only takes a few bites to cause a problem.  Also, the itchy pet often scratches or licks so much that adult fleas are hard to find because they are removed from the body.

“If fleas are the problem, why is my pet still itchy in the winter?”  In warm climates or our homes, fleas may survive in low numbers year-round.  Because flea allergy is so common, many veterinarians recommend instituting complete flea control before proceeding with testing for itching. For most allergic pets, year-round flea treatment is an important part of reducing itching.

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Talk to your veterinarian about testing and treatment options for your cat.

Food Allergy
Just like people, cats can be allergic to various food proteins and carbohydrates. Food allergies occur in up to 6% of cats with skin signs and up to 22% of cats with signs such as vomiting or diarrhea. However, no blood, skin, saliva, or hair test can determine if your cat has a food allergy. 

Likewise, changing your cat's diet to a different brand of food at the pet store won't help rule out food allergies in your cat. The only way to diagnose a food allergy is by placing your cat on a carefully selected diet, either a prescription diet or a veterinary nutritionist-formulated diet, for several weeks (food trial or elimination diet trial). 

Work closely with your cat's veterinarian on any diet change, as cats that stop eating are at an increased risk for hepatic lipidosis. 

Atopic Dermatitis (Feline Atopic Skin Syndrome)
Atopic dermatitis (AD) is an inherited predisposition to developing skin problems after exposure to a variety of commonplace and otherwise harmless substances. These include pollens of weeds, grasses, and trees, dust mites, and mold spores. Allergy testing by intradermal skin testing or blood testing can identify what your cat is allergic to in the environment.  Evaluating the results of these tests helps your veterinarian compile a list of allergens for a “vaccine,” or allergen immunotherapy, to decrease your cat’s sensitivity. 

Is Diagnostic Testing Necessary?

There are many anti-allergy medications to reduce itching. These medications do not cure allergies but can help decrease the symptoms. However, without addressing the underlying cause of the allergy, the itching will return when the medication is stopped. Long-term use of some anti-allergy medications, such as steroids, can result in many health problems. 

Working with your veterinarian to determine why your cat is itching enables them to use more specific and targeted allergy treatments.