
He is becoming naughtier by the day, and if left gets into all sorts of trouble. It is relly important to set defined boundaries, and has enough mental stimulation.
If your dog is very bright and works things out quickly you need to be one step ahead and to challenge him. This can be with games, teaching tricks, advancing his training or exercise.
What is important it that he does not get bored, as this is when they tend to get into trouble and chew your prize possesion or ruin your home.