A new cat has recently moved into the apartment next to yours, and your resident feline seems to be heralding the newcomer in his own way. You've caught him standing near the front door, posed with his tail straight up in the air as he sends a stream of strong-smelling urine down the wall. What gives? Your cat is exhibiting a very common feline behavior known as spraying.

   While it is not clear whether cats spray to claim territory or to warn trespassers to stay away, the behavior is usually accompanied by some sort of stress. Spraying may be brought on by the arrival of a new person, pet, or even piece of furniture into the household. Cats who are allowed outdoors may spray to let other neighborhood cats and roaming strays know who's boss of the backyard.

   Some indoors-only cats may begin spraying when they see new cats in backyard courtyards or out of windows. In this case, the best course of action is to block a cat's access to those views until the newcomer strays can be removed. And although both males and females spray, almost all unneutered toms begin spraying to attract potential mates and ward off rivals when they reach sexual maturity.

   What can you do if your cat's taken to spraying? If he or she hasn't yet been neutered, make that appointment today! If your unneutered male cat has just started to spray, very often neutering will put a stop to this behavior.

   To discourage repeat offenses, it is important that you remove all traces of the urine from furniture, rugs, walls and any other objects that your cat has deposited his scent on. To accomplish this, you can use a solution of water and vinegar and follow with a spray of a product such as Feliway, a feline behavior modification spray that effectively eliminates urine marking by your feline companion. In this case, be sure to follow manufacturer's instructions.

   Unfortunately, if your cat has been allowed to spray for some time, as is the case with many rescued tom cats, neutering alone may not solve the problem. In this instance, it is recommended that you use a product like Feliway or consult a professional behavior counselor.