Cat Tail Meanings TrustedHousesitters.com Have you seen these tail positions with your kitty? Which ones? Why does my cat shake its tail like this? : r cats A cat's tail is a powerful form of communication that reveals its emotions and intentions. When the tail is erect and twitching, the cat is usually excited or happy, while a straight up Does your Siamese cat's tail vibrate when excited? Why does my cat shake its tail like this? : r cats