If your cat is pulling out her hair, she could be suffering from stress or she could have a neurological or physical problem. Feline hair-pulling may also result from a skin disorder, parasitic infection or allergy. Put an Elizabethan collar on your cat to block the behavior and prevent open sores and infection, and see your vet for an evaluation right away.
Obsessive Compulsive Disorder
Cats can develop OCD, compelling them to groom themselves excessively or pull out clumps of hair with their teeth. This can result in hairballs from ingesting too much fur. It can also lead to hot spots -- open, wet sores that don't heal and can become infected. High-strung felines and female cats, especially Oriental breeds, are more prone to this disorder. If your vet suspects a psychological issue he may prescribe clomipramine, an anti-anxiety medication, or amitriptyline, which targets anxiety and contains an antihistamine to reduce itching and irritation.
Itchy Skin Condition
Your cat may be pulling out clumps of hair as a way to scratch an itch from flea bites, dermatitis, ringworm or mange. Your vet will perform a physical exam as well as take skin cultures to determine your cat's problem. Treating the underlying issue and relieving the itch can eliminate the behavior. Your vet may prescribe an anti-fungal or anti-itch cream, an antibiotic or a flea shampoo, or may recommend a change in diet.
Stress and Physical Issues
Some cats deal with elevated stress and anxiety levels by licking and chewing everything in sight. Houseguests, new pets, changes in schedules or even the relocation of a litter box can cause a kitty to feel a little haywire. Chewing, licking and pulling fur are manifestations of a cat who's at her wits' end.
Your cat may also be pulling hair out of body regions that are painful. For example, a cat with anal sac disease or a kidney infection may pull out hair around her hindquarters in attempts to relieve pain.
Home Treatment Options
Reduce stress in your cat's environment. Interact with her regularly and maintain strict schedules for feeding and changing her litter box. Give her several interactive toys to occupy her time when you're not around. Introduce new pets to the household gradually; if you have a disruption in your regular daily activity, make sure she has a secure place to hide out.