Guide dogs are very well trained BEFORE they are placed with their human. IF I remember correct, they will let you know IF they need to go out…plus, I think they are put on a schedule where they go out at a certain time every morning & at regular intervals during the day. They also have an amazing ability to hold themselves until their next scheduled relief moment. I do remember that they seldom have accidents.
Dogs can be trained to do all sorts of amazing things. When it’s time to clean up, a blind person could give a command, and the guide dog could point its nose toward its poop, and the blind owner could pick it up. Cool!