The medical term for itching is pruritus. Itching is defined as an unpleasant sensation within the skin that provokes the desire to scratch.
Itching is a sign, not a diagnosis or a specific disease. The most common causes of itching are parasites, infections, and allergies. There are many skin diseases that do not initially cause itching. However, itching may develop with these diseases due to secondary bacterial or yeast infections. It is possible that by the time itching develops the initial cause is long gone.
Itching may be general or confined to one area. The cat will excessively scratch, bite, or lick its skin. Your veterinarian will perform a thorough skin history and physical examination. Parasites, including mites and fleas, are often the first possible cause your veterinarian will seek to exclude. Next, the veterinarian will look for infectious causes of skin disease. Bacterial and yeast infections are also common causes of itching. If such an infection is suspected, your veterinarian may prescribe a course of antibiotics that lasts 3 to 4 weeks.
If the itching goes away, then the cause was a microbial infection. However, if the cat's itching is unchanged or only somewhat better, then the underlying cause may be an allergy. The most common causes of allergic itching are insect bites, food allergy, and an inherited skin allergy called atopy (see Skin Disorders of Cats: Airborne Allergies (Atopy)). Sensitivity to insect bites is readily identified. Cats that have seasonal itching are likely reacting to seasonal allergens. Cats with year-round allergic itching may have a food allergy or allergies to house dust mites in addition to seasonal allergens. Food allergy is identified based on response to a diet trial (see Skin Disorders of Cats: Food Allergies). During a diet trial the cat is provided with a diet that does not include the foods it has normally consumed. Your veterinarian will specify a diet, often one containing lamb or other meats not previously fed. To help your veterinarian isolate the food allergy, you will need to follow the prescribed diet fully and carefully and avoid providing treats that do not comply with the diet. Food allergies cannot be diagnosed by a blood test or skin testing.
Successful treatment depends on identification of the underlying cause. Cats with itching of unknown cause, or those in which treatment of the underlying disease does not eliminate the itching, require medical management. Usually, this means giving the cat prescription medication. In addition, essential fatty acids may be added to the anti-itching treatment program.
Last full review/revision July 2011 by Karen A. Moriello, DVM, DACVD; Thomas R. Klei, PhD; David Stiller, MS, PhD; Stephen D. White, DVM, DACVD; Michael W. Dryden, DVM, PhD; Carol S. Foil, DVM, MS, DACVD; Paul Gibbs, BVSc, PhD, FRCVS; John E. Lloyd, BS, PhD; Bernard Mignon, DVM, PhD, DEVPC; Wayne Rosenkrantz, DVM, DACVD; Patricia A. Talcott, MS, DVM, PhD, DABVT; Alice Villalobos, DVM, DPNAP; Patricia D. White, DVM, MS, DACVD