My wife and I brought home a new dog from the adoption center today. He is a 3 year old chihuahua mix. I have taken him out twice so far and he has pooped each time, but won't pee. When we brought him back in, after a while my wife caught him trying to pee in a corner. The people at the shelter said he is housebroken. I am worried he was taught to use newspaper or a pad for pee. How can I get him to pee outside as well as poop?