Your pup is very inquisitiveand interested in exploring the world around him. Right now his brain is geared toward soaking in everything it can. This coincides with a crucial phase in his development: He is in what is called the critical socialization period. Through 4 months of age is the single most important period influencing how your dog will behave as an adult. Now is when the foundation is laid for the rest of his life in terms of his attitude toward you, other humans, and other dogs.
It’s extremely important for your pup to have good experiences now, being introduced to all kinds of people and things he’ll encounter during his life.
Luckily, with his immune system finally matured, it’s now safe to take him to a wide variety of public places. It’s also important for him to play with other dogs as much as possible. Play with other dogs ensures that your pup will be dog-friendly as an adult and teaches him basic, important rules of intercanine behavior.
It’s not a substitute for your own efforts to socialize your puppy regularly, but a great help is to enroll in a local puppy class. These fun, informal gatherings expose your puppy to a variety of people and other dogs each week.
Starting around 16 weeks, your puppy’s baby teeth will begin t fall out. Most of these teeth are swallowed with the puppy’s food, and you’ll never see them. Permanent teeth will start to replace baby teeth at this age, and your puppy will chew even more than they did when their baby teeth were coming in.
Special thanks to the AKC and CKC websites for this great information.