We have a new lab puppy, 4 mos. old. We have two bells (like Christmas bells) that hang from our sliding glass door handle. We have trained him to touch the bells with his nose when we wants to go outside. We were very vigilant in watching him and when he started to do something inside, we picked him up quickly, and said "outside potty" When we got to the door, we rang the bells and said it again... "outside potty" After he was done, we gave him all kinds of praises... Now he goes right over to the door, rings the bell with his nose, and gets let outside. I love it!
He is such a good puppy ;)