Your cat uses every inch of his body to communicate his feelings and moods. It's difficult to interpret the body language of such a complex creature. While it's easy to know what a dog is thinking if he wags his tail, a cat waving his tail means something entirely different.
Depends on the Situation
Decoding your cat's twitching tail carries with it the same pitfalls as trying to interpret any foreign language. There can be multiple meanings, and it's possible that none of them make sense to you. When your cat waves his tail from side to side in wide arcs, the possible meanings include feeling intense distress, aggression, agitation, curiosity or annoyance. Guessing what your cat is feeling when he waves his tail requires awareness and a bit of deductive reasoning on your part. Look at what's going on around him. If he's hunting or playing with another cat he may be signaling that he's about to pounce. If you try to pet him when he's got his attention focused on something, his tail talk can indicate annoyance. If your cat appears to be sleeping but his tail is still active, he may be letting you know that appearances aside, he is still alert.
How Do They Do It?
Compared to cat tails, dog tails aren't as graceful or expressive. A dog can show remorse or fear when tucking his tail between his legs or express joy with a vigorous wagging. But cats can move their tails in all directions, agilely waving them in an flowing fluid motion when they feel so inclined. This is because cats have more bones in their tails than dogs do, plus they have a muscle in their posteriors that dogs don't possess. It's actually this bonus muscle that gives your cat his ability to switch his tail aggressively from side to side.
When your cat is waving his tail, it usually indicates a negative emotional state like aggression, agitation or distress, so it's best to leave your cat alone until he calms down. If you want to head off a possible fight between him and another pet, try to divert his attention with a toy or a treat. If your cat starts waving his tail while you are petting him, stop and allow his mood to relax a bit before resuming physical contact.
Other Body Cues
Your cat's tail isn't his only source of expression, as you are probably well aware. While an arched back and puffed fur aren't difficult to interpret, other, more subtle movements can be entirely missed if you aren't tuned into your cat's body language. If your cat holds his tail straight up, he is welcoming you with a friendly greeting. Wide open eyes means your cat is ultra-alert and ready for anything. If your cat has one ear pointed forward while the other is back, he may be unsure of something. If his eyes are dilated, he is interested or wary of something and may be preparing to attack or flee. If your cat's eyes are constricted, you can breathe a sigh of relief as that indicates he is feeling calm and relaxed.
Elle Di Jensen has been a writer and editor since 1990. She began working in the fitness industry in 1987, and her experience includes editing and publishing a workout manual. She has an extended family of pets, including special needs animals. Jensen attended Idaho and Boise State Universities. Her work has appeared in various print and online publications.