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Dear Doctor - Our experts offer strategies to address hair pulling in cats

Why is my cat licking herself bald?

[From Tufts November 2011 Issue]

Last fall, we first noticed that our 7-year-old female cat’s underside/nipple area was bright pink. During her annual examination, our veterinarian mentioned that our cat had licked herself bald there and on hind legs.

This cat is very mellow and laid back. Her only issue seems to be jealously/territorial issues with the other female cat of the house. A friend had suggested allergy testing. I’m concerned about the cost of allergy testing. What should we do?
S. Konkel

Dear S. Konkel: Hair loss (also known as “alopecia”) is a common problem in cats. To determine the cause, we have to determine if the hair is falling out or if your cat is licking it out. When hair falls out, it is usually the result of some systemic illness. When cats lick, bite or chew their hair out, it is usually because their skin is itchy or for a variety of psychological reasons. It sounds like your cat is pulling her own hair out.

There are numerous causes for itchy skin, with parasitic infestations, fungal infections and hypersensitivities/allergies being common reasons. Fleas are a common cause of feline hair loss. Pediculosis (lice infestation) and demodicosis (infestation with mites of the genus Demodex) can cause itching and alopecia in cats, although these conditions are uncommon.

Hypersensitivities/allergies are a common reason cats over-groom and pull out their fur. Flea allergy, food allergy and atopy (allergy to airborne substances) are three common causes of allergy in cats. Fleas deposit saliva into the skin when they bite, and allergic cats may show a severe reaction, even from one bite. Itching can be intense, and cats may lick and chew excessively at their skin, especially around the tail base. Adverse reactions to food may manifest themselves via the skin. Severe generalized itching, widespread small scabs and crusts (called “miliary dermatitis”), itching around the head, neck, ears and face, and self-inflicted hair loss due to overgrooming may be seen. Allergies to airborne substances such as pollens or dust can lead to itching and subsequent excessive grooming and hair loss.

Psychological disturbances are a common cause of self-inflicted hair loss. Some cats pull, chew or excessively groom their fur even though their skin does not itch. This may be a manifestation of stress or anxiety. In many instances, the cause of stress is obvious: a new apartment, a new pet in the household, etc. In most cases, however, the stressor is never discovered.

Making the diagnosis in cases of hair loss requires detective work. Parasitic infestations are diagnosed by carefully inspecting the skin for parasites (such as fleas), and performing skin scrapings and microscopic examination to look for mites. Flea problems should be suspected if fleas or flea dirt is noted during the exam. Even if fleas are absent, flea allergy can be involved. Ringworm is diagnosed via fungal culture of the hair.

Itching, especially around the head and face, is a common manifestation of food allergy, however, there are many cats whose only sign of food allergy is self-induced hair loss. A dietary elimination trial, in which the cat is fed a diet containing a protein source she hasn’t encountered before (such as duck, rabbit or venison) is necessary to obtain a definitive diagnosis. These trials require patience, as it may take from 3 to 8 weeks before improvement is noted.

Atopy — allergies to inhaled substances — can be a challenging diagnosis to make. Seasonal signs are suggestive of atopy, although signs can be seen all year round as well. Blood testing for allergy is thought to be unreliable. Intradermal skin testing (usually performed by an veterinary dermatologist), in which tiny amounts of allergenic substances are injected into the skin, is a more meaningful test. Dust mites, molds and seasonal pollens are the most common airborne allergens.

Once parasites, allergies, and other medical problems have been ruled out, psychogenic alopecia — hair chewing and overgrooming due to psychological factors such as stress or anxiety — must be considered. Your cat sounds like a mellow cat, however, not all cats with psychogenic alopecia are nervous, high-strung cats. Whether there’s anxiety over the other cat in the household is difficult to say. Ideally, the treatment of psychogenic alopecia would involve the elimination of the stressors in the cat’s environment. Anti-anxiety or anti-depressant medications are often warranted to control the problem.

With challenging cases such as yours, it may be necessary to seek out a veterinary dermatologist.
Arnold Plotnick, DVM, DACVIM
Medical Editor

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