THE ODDER WORLD OF BORDER COLLIES EXPLAINED: One of our followers - Rebecah Thompson from Galveston, Texas - wonders if anybody else’s collie has the same seemingly weirder habits as her Cecil here – i.e. “chattering his teeth and bouncing backwards while we walk. While he does this,” she says, “he doesn't watch where he's going and is always bumping into things!” It is possible that the teeth chattering here has more to do with the dog still trying to pant while clutching something in his teeth