Our guys pant after we have been running them hard, burning off some of that excess energy they seem to have in abundance. One of their favorite things to do is chase the laser pointer spot. We run it on the floor, up onto the bed, around the pillows, back to the floor, through their tunnel, back up to the bed............you get the idea. We are careful to avoid their eyes, and they love tearing up the hallway carpet to get their favorite "prey".
I usually stop and let them relax when I notice them panting. They calm right down, and then sleep well afterwards that night. Of course a turkey treat also helps right before bed. Gotta love that tryptophan!