>>336255some dogs, particularily large breeds like Great Danes, have much larger, heavier tails with bigger muscles and more momentum in the swing, unfortunately bones can only be so dense. The combination of a repeated impulse force against a hard object and the tendency of the tail to curl and thus concentrate the impact to a small area creates a high risk for injury in perpetual tight quarters.
That said, if your dog can't even wag its tail in your house without smashing things, your dog is too big for your house.