Fear aggression in a rescued german shepherd

Question
Dear Lorie,
In Dec. 07 I adopted a male, German Shepherd from a small rescue.  He is approx. 1 1/2 to 2 years old, and was neutered just prior to the adoption. It was a couple hours drive to pick him up, so My husband, son (2 1/2 year old) and the 2 most dominant dogs I have went to look at him. He was somewhat shy, but in no way aggressive at least not at all to people. We decided to get him and returned the next weekend to pick him up. He is a very loving dog and has never shown any aggression to me, my husband or my son. However, there have been some incidents with some of my other dogs, mainly over food, but as time went on this has improved. Shortly after getting him, I had friends over on New Years Eve. They had their children with them and we had no problems. Approximately a month later, one of the same friends came over again and when she came into the house, the shepherd acted aggressively toward her, jumping up on her. I immediately grabbed him and put him outside. We've had other people over since then and it appears to be getting worse. He acts aggressive now. I'll put him on a leash and walk outside with him and introduce him to the guests, and he'll act shy at first and then be ok. Tonight I had friends over (just 2) and I brought him outside on a leash. He didn't appear to be too concerned with the guest so I let him off the leash. He approached the guest (a teenage girl) sniffed her and appeared to be ok. She even pet him and there was no problem. He stepped away from her and she took a step and he went crazy. Ears back, tail down, teeth showing. I immediately grabbed him and put him in his crate inside the house. He is so scared when he goes to the vet that he urinates from fear. He did this occasionally when I first brought him home with us, but I didn't think much of it at the time. What do you recommend. I have 5 other dogs, have owned a German Shepherd before and never had a problem. The previous one was with us since he was 8 weeks old and was socialized at a young age. He was a wonderful dog his whole life. I'm just upset because we love our dogs and want them to be part of our family when friends are over, but at the same time I don't want one of our dogs biting our friends. What do you recommend? I don't encourage his bad or fearful behavior by saying anything like it's o.k., on the contrary I try to immediately correct it by saying "no". What else can I do and what do you think is triggering the behavior I just explained where he appears o.k. one minute and Cujo the next? Thank you.

Answer
Wow Susan from what you have told me it seems like he has some fear issues that need to be worked out. From what I can tell your house has been his safe point so entering guest are now a threat and with you removing him from the threat (which yes seems like the logical thing to do)is making him want to defend his territory more.He must learn to face his fears not be removed from them.This may take some time but can be done. His acting like Cujo is done out of fear,and we all have survival instincts when we approach fear, his just needs to be corrected.   
I would recommend that he is taught some obedience training to focus on you as his protector and leader and redirect his fears.
Find an animal behaviorist (trainer) in your area and work on this, this is something you can not do alone. In finding a trainer ask many many questions remember the golden rule DO NO HARM.There is no need to harm a dog to break fear aggression.  Ask your Vet or local Humane society for  recommendations to a trainer in your area.
Until you find a trainer, don't baby him when he gets fearful just redirect with asking him to sit, fetch or any other things he knows how to do. If he does what you ask REWARD him. As for company, I would pull out his crate and put it in where you and the company are, no one is to pay any attention to him what so ever. This sets him up to being safe in his crate but also watching from a distance that these people in his house are ok, they didn't come to hurt him in fact they don't even know he is there thus easing the fear level.
Please keep me posted on what is going on with this, if you have trouble finding a trainer in your area let me know, I will do my best to find you some recommendations.

Lorie