By nature, All dogs breed are playful and few dog breed occasionally chase their tails from time to time. It not a problem its something funny, however,  in most cases you cannot distract your dogs from chasing their tail,  and the reason dogs may chase their tail. It mostly just be an expression of a playful temperament.

in this video lex the beagle rottweiler has fun chasing his own tail, but he can barely keep himself from falling down!

Video Source : morten midtsund