beaner said:
If you want to make sure they understand this, you catch them when they're doing it, you pick them up, flip them on their backs, say "NO" pretty loud in your lowest voice (like growling) and bite/nip at their lips.
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Um, no. I would NOT do this. "Alpha rolls" are an outdated technique, and you definitely do NOT need to bite/nip your puppy's lip.
What I would do, is simply say "no" you don't need to yell it, just say it in a firm voice, and then give the puppy something he *can* bite, like a bone or a toy.
I realize your skinbaby is too young to be taught how to deal with it, but you can certainly teach him to *yelp* whenever the pup bites at him (a loud AW or OUCH would do), and then immediately step away from the pup (or have one parent remove the pup from the skin kid). The yelping sound is what a littermate would do to let the puppy know he's being too hard, and ending the play will be the negative consequence to his nipping.
I would also like to add, while we're on the subject, that children and dogs should never be allowed to play unsupervised (not that you don't supervise them... just throwing it out there).
Also, you might be interested to know, that you should teach your son to *not* "hug and kiss" the puppy. It might be fine now, but when you have an adult dog, hugging (putting your arms around its neck area, while hovering over him) it's a dominance act and can be considered a threat, and might POSSIBLY cause your dog to react accordingly (warning growl or nip). I've heard endless accounts of dogs nipping children, and when questioned their parents would say "he/she was only trying to give the dog a hug..." just not worth the risk IMO.
Hope this helps.