I am new to owning my beautiful Doberman who is 4 months old and named named Diezel. He is so sweet. He learned sit, watch, lay down, wait(for food and treats) and a small stay at 9 weeks old. He is so smart. I notice we all have the same problem with play nipping and scratching. Diezel has never growled at me or my son or at anyone we allow him to meet. He goes with is everywhere, church, stores, doctors appointments, he is always friendly and loves everyone. He will bark and growl on the walk at some passing by. We are working on full stay, potty training, jumping up and this play nipping. Any suggestions?