Getting greeted at the door by a wagging tail is one of the purest pleasures of owning a pooch. No matter how big, small, or fluffy your dog’s tail is, they will move it around, often at great speed!

There are few things cuter than a contented kitty taking a nap when its tail starts to wag or thump up and down. Videos of this adorable behavior abound on popular social media sites, and owners are ...