Almost every day my two cairn terriers, Fearghus and Fiona, will play fight and run around the living room like crazy dogs. It sounds horrible and when you see their big white and sharp teeth it looks scary, but all they're doing is having fun, lots of it! I took a quick video of them in the act.
Aren't they silly dogs? We love them so much. And yes, our living room is dog-proofed with sheets on the recliners and dog crates and the ex-pen. They spend most of their time there except when it's bedtime. Then Fiona goes to her crate and Fearghus tries very hard to get to sleep on the bed. The little stinker is so cute that quite a bit of the time he does.