Startle response and redirect - Just as the puppy bites down, make a sudden and abrupt, high-pitched yelping sound. This would be the type of sound that a litter-mate would make if bitten by the puppy. The sound should be sudden and sharp so that the puppy is startled and stops the behavior. Try not to pull your hand away, even though your reflex will be to do so. A dog's instinct is to give chase and if you pull your hand away quickly, he'll go for your hand again. If done correctly, the puppy should instantly remove his mouth and look confused. At this point, quickly substitute a toy, such as a ball, that the puppy can chew on. This redirects the puppy's biting behavior to the toy. The puppy learns that it is no fun biting you, but chewing on the toy is. You will need to do this multiple times if the puppy gets excited during play. However, if the yelping makes the puppy more excited, try another approach.
Teaching a Puppy “No Bite” – Dog training blog, Austin tx
Why did your sweet dog bite you? All dogs can bite, and given differing circumstances, all dogs will. Although we humans regard any bite as aggression, for dogs, biting is a natural and normal means of canine communication and defense. It’s actually surprising that our dogs don’t bite us more often than they do!
Jan 19, 2010 - Dogs will use their bite for many different reasons
This is SOOOO important!! My current Search Dog came from a German Shepherd breeder that had produced generations of working and sport dogs; it was literally in her genes to bite and hold. We called her "pirhana puppy." Her prey drive was also highly developed so just walking was often enough to elicit a "grip" on a foot or ankle (she was never fooled into biting at fabric of a pant's leg, only "meat" would do); even with shoes on, those needle sharp puppy teeth could inflict injuries. "Traditional" training in this case would have been disasterous, imagine a dog with generations of bite and hold genetics that was never taught control who finally does feel the need to bite? Additionally she has a very high pain tolerance... just how hard are YOU willing to correct a tiny puppy? and would likely have resulted in biting harder (it is desirable for protection dogs to respond to pain or agression by gripping harder). The method Melissa described (teaching her to control the pressure) worked like a charm.
There is no difference in this based on breed, age, or size