With very young puppies,
this sometimes works wonders - it's the same thing that
happens when they get too rough with another puppy.
The wounded puppy yelps and runs off, refusing to play
for a bit. The yelp must be startling enough to stop
the behavior. If nothing changes, you probably weren't
a good enough actor.
However, depending on your pup's personality, this
could also incite him to become aggressive and chew
all the more (thought bubble: "I've wounded her,
I'm going in for the kill!") In that case, you
may need to use some aversive methods.
A first approach is to try Bitter Apple. Use it liberally,
and not just a light spray. If you make a big impression
the first time, it's likely to have a better effect.
(If you doubt that, give it the lick test yourself!!!)
Some puppies need more. It's helpful if you could
enroll in a puppy class designed especially for young
puppies in order to get the proper guidance, because
it's sometimes difficult for a novice trainer to recognize
when aversives should be escalated. If you are reading
the puppy wrong, increasing aversives could actually
make the problem worse instead of better.
To introduce an element of "natural discipline",
grasp the recalcitrant pup by the scruff of the neck
with one hand, place your other hand over the top
of his muzzle, gently pressing his muzzle towards
his chest as you say, in a low, growly tone of voice,
If they begin to throw a tantrum and thrash around
trying to bite, just hold the line until they "give
in" and "say uncle" (quit resisting).
You should not find it necessary to get aggressive
with a young puppy. Simple restraint is usually enough
to get the message across.
Absolutely do not use any stiffer discipline without
guidance from an instructor. An example of overkill
is the alpha roll. Most young puppies simply do not
need that level of discipline, and you can really
damage the relationship by using it.