Why does my dog chase its tail? Many puppies and young dogs chase their tails for entertainment – it’s a built-in toy that can alleviate boredom. If your dog chases its tail compulsively, you might want to seek a vet to make sure there isn’t an underlying health problem. There could for example be something that itches. Dogs can also suffer from an obsessive-compulsive disorder and constantly chase their own tail or chew on some other body part.