You may think dogs are the only ones who chase their tails, but keep an eye on Kitty. Sooner than later, you'll see him going in dizzying circles. Of course he realizes it's attached to him, so why does he try so hard to catch it?
Kitty is a natural hunter. The instinct to chase begins when he's just a tiny kitten. Even if he never learns to hunt for food, he'll still have the desire to chase down anything that moves. His mom will teach him how to properly chase, capture and kill his prey so he can be a successful hunter when he grows up. If Kitty has ever brought you his kill, whether it's a real mouse or simply his favorite toy, this is him trying to show you how to hunt. He may never have to use the skills he learns to feed himself, since strolling to the food bowl isn't exactly a dangerous hunt.
Practice Makes Perfect
Kitty will practice his ninja skills on his pals, and sometimes even himself. As a kitten, he may pounce on Mom's tail or tackle a sibling. This is all in good fun, but it's honing skills he'll use later to capture a mouse or a lizard. His tail, twitching and fluffy, may prove too tempting to ignore. He'll capture it and spin in circles trying to “kill” his tail. Eventually he'll settle down for a grooming session once he feels like he's played enough. He realizes it's attached to him, so he probably won't hurt himself, except for possibly injuring his pride if you catch him in the act.
Movement Equals Life
There's a good reason his tail is a becomes a target for hunting practice: it moves. Movement, even of inanimate objects like circles or dots, indicates to both you and your feline that something is alive. This is why laser pointers or a tugged piece of string are favorite things for your Kitty to chase. Humans can recognize a few points of light arranged like a stick figure as a human analog. Cats do the same thing. They perceive a moving object as either something to catch or something that may try to catch them. This survival instinct is part of why cats have evolved into such successful hunters.
While most of time tail-chasing is a harmless past-time, sometimes it might be an indicator of something more serious. Feline hyperesthesia is often thought of as a feline form of obsessive-compulsive disorder. Kitty may act possessed, running from a threat no one sees but him. He'll have “crazy” moments, where he becomes hyperactive or aggressive. His pupils will dilate and he may become fixated on his tail. He'll chase it incessantly or groom it to the point of losing his fur. He'll be hypersensitive to touch, and what began as a cuddling session may turn into an episode. Make sure he has plenty of opportunities to play and hunt, giving him a chance to get excess energy out of his system. Keep an eye on him so he doesn't hurt one of his buddies when he has an aggressive episode. His vet may prescribe anti-depressant medications to balance his moods. If Kitty seems unusually aggressive or begins to chase unseen objects, visit his vet.