Feline urine-spraying is different from inappropriate urination -- not only is the chemical makeup of the fluid different, but the method of release is different as well. If you aren't sure whether your cat is urine-spraying or simply urinating, watch him as he does it. Telltales make it easy to determine what he's up to.
Backing It Up
Cats generally spray vertical surfaces such as furniture, walls, curtains and the sides of bedspreads. Your cat likes to spray these surfaces around facial height, so he remains standing up on four legs without squatting. When he finds a surface he wants to mark, he'll back up to it, his backside facing the target.
Wiggle and Spray
Once he's in position, a cat intent on urine-spraying lifts his tail, which would otherwise only get in the way of his spray's trajectory. He then shoots urine straight back in a steady stream, coating the surface behind him. Oftentimes, his tail -- or even his whole body -- twitches before and during this process. If you are trying to stop your cat in the act, the wiggling, erect tail is your last warning before he sprays. Call out or clap sharply; even then you might be too late.
Urine spray is distinctly different from normal urine in two ways. The first is volume: When a cat sprays urine, he releases a relatively small stream of fluid, considerably less than he would when relieving himself in the litter box. The second noticeable difference is the smell. Urine spray has special hormonal compounds in it that give it a significantly more pungent odor than typical cat urine.
Why They Spray
A cat sprays for one of several reasons. The behavior is more prominent in unneutered male cats, because those odorous hormonal compounds in the spray serve to attract mates. Cats may spray as a way of marking territory or responding to stress -- neglect or the introduction of a new pet, for example, may compel your cat to spray throughout the house.