Puppy biting training is important to begin as soon as you bring your puppy home. Puppies communicate with their mouths, so they don't know that humans don't find this acceptable. There is a simple, non-threatening way to teach them not to bite, which produces results quickly.
Inadvertent Rewards
So often when training our dogs, we inadvertently reward behaviors that we aim to correct. For example, when your dog jumps on you, you might yell at him and push him off. However, you are talking to him and touching him-both things he enjoys. Thus, the behavior will continue.
This often happens with biting. We are often told to hold our dog's mouth closed or pinch his nose. Some training philosophies even suggest biting the dog back. However, these methods teach your dog that it's okay to communicate that way because you're doing it as well. It is also going against the way that puppies teach each other not to bite too hard in litters.
"Ouch!"
When one puppy gets too rambunctious in a group and bites too hard, the other puppies do not bite him back. Instead, they all yelp and turn their backs on the puppy and walk away, ending the game. To get the game started again, the puppy must apologize and play nicely during the next game.
This is effective with human-puppy interactions as well. Each time your puppy bites, yell "ouch" or something similar, even if it doesn't hurt. You want your puppy to learn that teeth on a human is never acceptable. During this time, end all games that involve rough-housing and use only toys when playing with your puppy.
That noise must always be followed by the consequence, which in most cases will be turning your back and storming away. To make this effective, you must be dramatic. The "ouch" should be loud and memorable, immediately followed by you stomping away, even going into another room and slamming the door if necessary. If there is more than one family member in the room, everyone should leave.
Leave your puppy in isolation for only a minute or so. Then, give him another chance. If you are consistent with this, biting will be reduced almost immediately.
Inserting a Toy
Puppies need to relieve energy, so if you are in the midst of a game, give your puppy the opportunity to chew on the right things. Rather than your hands, your puppy should chew on a stuffed or rope tug toy. When your puppy nips you instead, yell "ouch." Then, offer your puppy the toy. If he takes it, the game continues. If he bites your hand again, you repeat the yell and then storm out of the room.
Timeouts
If you are in the middle of something and don't want to storm out of the room, attach a small leash to your puppy. If he nips, yell "ouch" and use the leash to lead your dog to his timeout place, either a crate or a small, quiet room such as the kitchen or bathroom. This also isolates your puppy, reducing the likelihood that he will repeat the behavior.
As with most training behaviors, consistency is the key. Have everyone in your family respond exactly the same way each time your puppy nips. If you are consistent, this behavior will improve in days.