There might be the occasional yelp, but usually no blood.
When puppies bite, they are often teething and just trying to sooth their tender mouth.
Fill a sock with some crushed up ice cubes and tie a knot in the end of it.
This is a great teething toy for puppies.
If the biting is aimed at a hand, say, "No bite" and provide one of the puppy's toys for him to chew on.
When an adult dog bites, it can be for multiple reasons; something scared him, he got carried away when playing, or he's aggressive.
The aggressive biter is the one to worry about and who training should begin right away with.
Dogs who use biting in an aggressive manner are often confused about their role in the leadership chain.
He needs to learn that he isn't the alpha dog.
Here are a few ways to show you are the alpha "dog" in the house: Don't allow the dog on the furniture-Don't pet him when he demands it, do it when you want to-Feed him after you've eaten-Put toys out of reach when you are finished playing with him, so you are in charge of playtime-Enter a door before you let your dog in All of these should show him that you are in charge of things, which should help the aggression situation.
When it is only strangers that get bitten, this can be curbed somewhat by letting him meet new people more often.
If you have a dog that you received as an adult, he may not have been socialized as a puppy and this is where the fear of strangers comes in to play.
Keep him on a leash if he is prone to nip at strangers, this is the best way to avoid any accidental biting.