Physically, his stomach can handle bigger, less frequent meals, 2 or 3 a day. His permanent teeth have usually grown in completely, and they will continue to grow until the age of 8 months, when they reach their adult size. This process may make him irritable and nervous, or it may not affect him at all. In any case, this is the most destructive age, when his favorite occupation seems to be to chew, gnaw, and tear things apart. Let him vent his natural instinct on the appropriate toys, not your furniture, and try to use up his energy with plenty of exercise and play.

Psychologically, this is a crucial period. In wildlife, packs are formed at the beginning of winter, when spring born puppies are 5 or 6 months old, and this is the age when domesticated dogs need replacement activity, and above all, leadership. They start to develop territorial instincts which can lead to aggressive behavior if not controlled.

A puppy who always allowed to have his own way now may be spoiled forever. His budding sense of social dominance and subordination makes it vital for you to establish your authority without destroying his self confidence. You might even begin simple training, but restrict the lessons to those requiring energy and willingness, which he possesses in abundance, rather than self control, which is practically nil at this stage.

What he needs most is outdoor play, a generous, drier diet, chewing toys, loving kindness and a slightly higher standard of discipline.