Get some really good cleaner and make sure you really get everywhere he has peed. You are probably going to start from scratch and have to crate train him, taking him out as often as possible, praise him for going outside and put him in the crate when you are gone or can't watch him. Even if you are home all the time use the crate so he learns to hold it. A trainer I know tells people to even have their dogs on a leash in the house, tried around them, that way you are watching him and at the first hint he is about to pee he is already on the leash and you can quickly walk him outside.
__________________  Teapot Club Member |