You can't expect him to hold it on a walk. Mine pee at least twice and Loki will always poop even if he had JUST gone in the yard. To your dog, the whole point of the walk is to sniff things and pee and poop on stuff. That's why we carry 2-ply poop bags. They even come in pink! Every dog owner has to do this, little dogs are no exception.
Ha I have no idea why it decided to put lips in the title??