Yikes, I can see why you're concerned!

Other posters have some good ideas. The woman who led our puppy classes also recommended a "time out" if all the other methods failed, but didn't recommend using a crate for that if you were doing crate training. The reasoning, I think, was that if the crate is the dog's "safe place", then you don't want it also to be associated with punishment.

She recommended that if after correcting using one of the other methods didn't work, put the puppy in a bathroom or laundry room for a time out - only 30 seconds or a minute, nothing excessive.

I think the thing that made the biggest impact for us was staying consistent - we'd try one thing for a week, and if that didn't work, then we'd try another method. At first, we were trying more than one thing at once, or we'd try something a couple of times and abandon it as "not working". It takes puppies a while to connect the behaviour with the consequence, and we weren't giving Barney enough time to make that connection.

oh I feel your pain. I agree with the time out. when storm got out of hand that is what I did and it worked.

also, when storm was little he use to chase my young nephew and bite his butt. I didn't know what to do, so I decided I needed my nephew to help train storm.

we started small. My nephew started with sit, something storm new and would give him a treat. then we moved up to other things as storm learned the trick.

this worked for me. storm started to see him as a leader. Mathew nows gives commands and storm listens. any child can tell storm what to do and he listens.

I also had Mathew teach storm swimming eticate. storm use to scratch the kids. It was mathew that trained him in the water. they are now great swimming partners. mathew doesn't have to tell storm anything, storm just knows.

hope this helps.