Tail chasing

It seems like a pointless and fun behavior, and it actually kind of is. 

Especially for puppies, chasing their own tail can be a form of play for dogs. Adult dogs may do it out of boredom and a lack of physical and mental stimulation. However, it can also be a way for dogs to express their discomfort. 

Tail chasing may mean they are experiencing itching from fleas or other skin irritations. In some cases, tail chasing can become a compulsive behavior for dogs with obsessive-compulsive tendencies.