Maybe it's TMI but the inside of a fursuit head can get pretty rank after just a short amount of suiting. So when I'm decapitating myself in between suiting runs I jam this USB-powered 80mm fan from ThermalTake into my mouth to try to freshen up a bit. I have it set up so that the air blows out, in theory sucking in fresh air through the eyes and/or (if propped up) from underneath and blowing out the smelly air through the mouth.

It's the fursuit equivalent of giving myself breath mints..