Our 6-month old German Shepherd puppy was the worst nipper in the world, and still sometimes has bad days.
For most puppies, the most effective remedy is ending playtime and removing any attention (positive or negative) until they stop nipping. The second they start playing nice, reward immediately. Of course the moment you reward, they'll go back to nipping.. so just repeat the process until they get the picture. German Shepherds, even as puppies, are incredibly smart dogs and will catch on quickly.
Keep in mind, she is a puppy, so don't expect anything close to perfection. Be lenient, pick your battles and remember, she will test you, so be patient. Puppies explore the world with their mouths, so a lot of nipping is totally normal.
When it came to our puppy, nothing worked. We consulted 3 different dog trainers (all reputable and successful) on methods to stop him from nipping, because I would literally have bloody fingers and wrists. When we would get up and walk away, or put him in his cage, or redirect him with one of his toys, he would get mad because we weren't playing his way, and would nip more.
In the end it took a little bit of aggressive dominance to end that behavior plus a few others that were major "no's"--to assert ourselves as the pack leader. When he would get mad that we weren't playing by his rules, we would pin him on his back. He would squirm, fight and try to bite us, but as soon as he'd calm down and submit, we'd let him up and give him a ton of praise, lots of playtime and fun stuff.
You have to be careful with that particular method.. trainers don't typically recommend it because if it is not done correctly, it can cause aggression or anxiety in your dog. You have to be able to read your puppies body language and adjust accordingly.
You don't ever want to pin them into a vulnerable position (on their backs) when there are other dogs around, and avoid it when there are people around that they are not familiar with. This is a last resort method to deal with a stubborn dog. This method worked for us, our puppy rarely nips anymore, is happy and loving life!
Sky (aka: Hans) - Male GSD, 6 months
Lake Stevens, WA
Last edited by thewaiting28; 03-01-2013 at 07:01 PM.