Very cute puppy! But why are you letting this happen? The tail-chasing can become an obsession, which you definitely don't want. I know puppies do this, but it's better to distract them away from it. And playing with the door stopper is letting your puppy play with your things, which isn't what you want them learning. If your puppy's bored then finding the 'right' thing to play with is what they need to learn. Buster Cubes are awesome toys and worth every penny, IMO. And real bones, sturdy rubber toys, etc. I leave lots of those things out so my puppies can make the right choice, in terms of what's theirs to amuse themselves with.