Adult dogs can be housebroken using these same guidelines. However, it may take longer.
All dogs are naturally clean.
Housebreaking depends upon the instinct of dogs to keep their bed clean. Their own private place gives them a sense of security. Confinement is NOT cruel unless abused. Do this by constructing or obtaining a box which will have a door or lid on it with adequate ventilation holes. The box should be big enough for the puppy to turn about in and even lie at full length, but no longer.