Maple had no problem going through the dog door flap at my mom's house, so I decided it was high time for her to do it at home. It took a few days and several instances of leaving her outside, but now she's doing it on her own regularly, and pretty voluntarily. ;-) But really pugs don't like them because of their little pressed-in noses; they don't want to push on them with their faces. Instead, Maple uses her paw to get it started and then pushes with the top of her head.