Hello, so I have a 1 year old male GSD who was recently neutered. He is a timid shepherd, he doesn't like to be pet by anyone except me and my family or people he regularly sees, but I don't have problems with him being aggressive towards people unless we are in my house. When guests come in he barks/lunges at them, but then he will calm down after a few minutes. However if the guest may try to pet him once inside the house or walk towards him in some cases he will begin to bark and become aggressive again. I started working with an in-home trainer about a month ago and haven't seen a lot of progress. The goal with the trainer was to use a "place" command which my dog will go on his blanket and have time to observe the situation while people enter the house. However he will break "place" unless he is on a leash when someone enters. The trainer uses a leash correction with a choke collar to try and negate the behavior when my dog barks/lunges. Does anyone have any suggestions? I believe part of the problem is my dog is timid as it is and I need to build his confidence. I really want to feel comfortable inviting guests into my house with my dog. Thanks!