Puppies LOVE to bite. It’s part of how they explore their world. Fortunately, their mothers and litter mates tell them in no uncertain terms when they bite too hard. With much repetition of these reactions, a dog will naturally develop what’s called bite inhibition, where they will still mouth each other (or you) but they don’t chomp down hard.
Since puppies are often taken away from their mothers and litter mates while they are still quite young, it may be up to you to finish the bite inhibition training. This is actually one of the most important things you can teach your puppy, since dogs have so much strength in their jaws that even a playful nip can do a lot of unintended damage to a person and can also scare people (especially kids) badly.
So what can you do?
If you have other dogs at home, they may well do some of this training for you, though some of my older dogs have been more patient than I wished with my new puppies!
Make arrangements for your puppy to have play dates with other puppies and dogs (once your puppies have developed enough immunity to be around other dogs).
Be sure to have some good chew toys for your puppy.
One of the best resources I’ve used for bite inhibition is Ian Dunbar’s classic DVD, Sirius Puppy Training. That link goes to my review of it. Of all the things I’ve reviewed on my site, this is the one that has sold by far the most copies.
I’ve been helping a friend train her two Doberman puppies, now six months old and pretty close to full grown. They are littermates, and that helps in this regard, as they play together a lot and so teach each other bite inhibition. But when I visited them about three weeks ago, the female was trying to nip me way too much. I tried yelping in pain and when that didn’t deter her, I changed to a stern NO. That helped but I could see her compulsion to play-bite me was still there. Yesterday, I saw them again — and she was much better! This time she was trying to jump on me. There’s always something!