Seems to go in line with my 11lb Shih-Tzu (He's a little fluffy right now, so I'd say he might be pushing 12lbs!) sounds like an elephant whenever he comes home from going #2 and runs around on the carpeted floor.
He runs with so much energy/spunk that he actually lifts his front paws above his head as he gallops.
Animals are fun, aren't they?