I used a rabbit fence folded over on itself and made a corral that I set on top of a protected floor and put puppy pads in with a sheet over top. then old towels draped over sides of fence. The mother dog could step in easily and get out when she liked. the sheet had to be removed and replaced with the pads once or twice a day. old sheets I used many ... they were disgusting but ....the corral idea works with these guys in the house. I had them in because it was too hot!! once they are too big for the corral then mother uses it alone to get a break from them in the run. I am hoping it will be a stay on your side of the fence thing but thats just a dream