I have two suggestions. When you go to Dotties bring some pads and put them all over the place. Also, when you go to your friend's, both of you take the dogs for a walk together. Your dog may very well do his business outside, too.
I have a similar problem. Ruger normally goes outside, but I have some papers in the house for when I want to sleep late. When I take him to my girlfriend's house her dog always barks to go out, but Ruger won't follow him into the yard and goes in the house. I put papers all over, and he often uses them. |