There are many reasons why your cat is losing fur. Most times it is because of chewing his hair and breaking it off or yanking it out through over-grooming. Sometimes you may actually catch them in the act of chewing out fur, or maybe you’ve noticed that they are grooming a lot. It is more likely though that you have noticed a hairless patch or two. Occasionally, you will notice clumps of hair in their normal hangouts, or you may just notice a sudden increase in hairballs.
Hair loss from any cause is called alopecia. To treat the alopecia, it is necessary to determine the cause of the problem.
The most common cause for cats to pull out their hair, especially around the base of the tail, is an allergy to flea bites. For cats that are allergic to flea bites, it can only take a single bite to produce an intense and sometimes prolonged reaction.