Wow. Dogs just never stop asking to be taken for a walk, do they?

It just occurred to me that MAYBE it has something to do with the apartment. Even though the dog knows how to go out on his own, he only seems to do so when he needs to go, or when my sim is already down below. So maybe it's about not being outside enough, and the game doesn't give him any reasons to just go out and play in the city.