Well, I think the best idea would be to keep a tight eye on his where abouts (even if you have to tether him to you and/or keep a leash on him). Sounds mean, but you need to catch him before he goes potty and how else other than to keeping vigil. I would just retrain him to potty outdoors. Put him out on leash and say (well, what ever words work for you, but always say the same thing...), like "go potty" or "go pee" (I say, "go quickly"). Take him out at least twice in the morning, twice in the afternoon and twice in the evening (one of them being right before bedtime). Of course it's up to you how many times you decide to take him out, but if he's an adult and he's learning to potty outside (as my new 1 year old yorkie IS...ATM), this is what is working for me. I hope I have been helpful.
