Why Do Cats Shake or Vibrate Their Tails? Vet Verified Reasons Explained Catster It looks like they are vibrating. When a cat's tail shoots straight up and quivers or rattles at the tip, it is the highest form of excitement they can show. It's a A Guide to What Your Cat is Communicating: A cat's tail is far more than just a balance toolit is a sophisticated emotional barometer that broadcasts their internal world. When your feline Why Do Cats Vibrate Their Tails? Reading Your Cat's Body Language Kinship Cat tail signs: What your cat's tail tells you