Toddler biting or hitting? Ask the dog trainer
My sister recently adopted a rambunctious golden retriever puppy who is a doll but had developed the bad habit of not exactly biting, but definitely nipping playfully when playing with the kids. He wasn't hurting anyone, yet, but she was having a hard time getting him to stop.
So I asked my friend Steve Pica, a Clearwater dog trainer. His answer was the exact method I used to stop my toddler from biting in a week. Listen to this advice, mothers of biters, hitters and pinchers. Getting them to knock it off is the same way you get a dog to stop biting while playing.
You pick a particular word like "OW" or "OUCH!" and you kind of over-react. Whenever the dog's teeth touch a bit of skin, no matter how slight, you say "OW!" and put him down immediately and walk away from him. Give it a minute to let it sink in that he's lost your attention, because that is just the worst thing to him. Then return and play and make a point of showing him how to play gently and give him praise when he does so (for a toddler I would add teaching short phrases like "gentle touch"). But if he nibbles at all, do it again and say "OW!' and put him down and/or walk away. It won't take long for him to get there's a negative consequence when he nips.
Postscript: Neither the puppy nor my toddler had a problem with biting after a week of this, though sometimes a little tune-up or reminder was needed.
-- Sharon Kennedy Wynne