Lock Jaw

Question
I just adopted a 16 m/o male GSD.  He was neutered about 2 weeks ago.  We were at the dog park...where he has been before without any problems, but today he locked his jaw on the neck/ear of a 4 month old puppy.  It took one of the men in the group giving him a swift kick in the gut to let go.  Is this due to hormones???

Answer
Sounds like he's an alpha pup. If you haven't already started him in obedience do so immediately. If you're not walking him briskly two times a day, that's another one to start immediately. Keep him at your side unless you release him to potty. Be sure you have your pup under control before going back to the dog park. In your web browser type in Alpha Boot Camp, give it a read and implement the ideas. They'll help you develop the right relationship with your pup.
Neutering will help but training and relationship is the key.
Cindi