Our dog is a year old shephard/golden mix female who has a very gentle, friendly and loving nature. The problem is that she freaks when my brother visits. The first time was at Christmas, and although our dog had no interaction with my brother before, she just went nuts when he came to the door. She barked and lunged at him and had a hard time calming down. Oddly, she seems to want to like him, or so it would appear when she immediately goes to his hand and licks it as if in apology after I restrain her. I had her choke collar on and restrained her with a snap of the lead and a loud, harsh NO! but she seems fearful of him. Each progressive visit (there have been three in all) she seems to feel somewhat wary, but attempts to be friendly with him until he enters the kitchen when I am in it, or if he approaches my elderly mother. I sense that she is being protective of us, but am totally thrown by her unease with my brother who is a kind, friendly person and has shown no aggression at all. We wonder if she was mishandled before we got her at 4 months at the Humane Society and the person resembled my brother? She is timid when initially approached by men, but warms up right away as a rule, except with my brother. The most recent visit, she lunged at him when he entered my kitchen - after licking his hands and being okay while we sat out in the yard. She doesn't seem to try to bite, but her sharp bark and leaping send a clear message of "don't mess with me". I've reprimanded her with her choke collar, made it very clear this was not acceptable behavior with my brother, but nothing seems to really be effective. I would appreciate any help with this!

It sounds to me like she is afraid of him. Her fear is what is causing the aggressive behavior. You can punish the aggressive behavior, but it will not change that she is afraid of him. I would suggest that you work to help her overcome her fear. If she's not afraid, then she won't be aggressive. For this, I like to recommend Classical conditioning, which is where you condition a response to an external stimulus. For example, you would teach her that when your brother is present (the external stimulus), Good Things Happen to Dogs (the conditioned response).
Does your brother live near enough that you could do training sessions three times per week (or more)?

Lisa, do you know that now one has every spelled out like you did in the last post about conditioning and response.

Thank you from a novice dog owner/trainer/behaviorist.

Lisa: Thanks for the advice! My brother lives in another part of the country and we don't get to see him much, but he is here until tomorrow afternoon and I can certainly start working on it before he leaves. He's coming back out in August, so I will resume again then. I actually have tried giving her treats when he is in the room, and giving them to my brother to give to her and she is fine with that and with him at those moments, but watchful. Then tonight when he moved toward my son who was lying on the floor, the dog got frantic again and yelped and lunged at him - she seriously seems feel a need to protect us from him. I've never seen her act this way to anyone else.

Kimberly,
One or two repetitions of treating will not be enough to create an involuntary response, which is the goal of Classical conditioning. If he's leaving today, you do not have time to do this properly with your brother. It takes weeks of short socialization sessions, three to five times per week (I would recommend five or more for your dog), before the response starts to become automatic.
You could do training setups with other men, though, between now and August.
The first step is when a man is present, YOU feed her the treats, and don't ask anything of her. Don't ask her to interact with the man or approach him, and instruct him not to stare at her or approach her. You start at this basic level until she is comfortable with it (a week or two, depending on the dog's comfort level), then and only then to you progress to having the man toss the treats to her from a distance, but NOT try to touch her or stare at her. Once she's comfortable with the treat toss from 6 to 10 feet away, decrease the distance to four feet. Once she's comfortable with that, then have the man hold the treat in the flat palm of his hand and let the dog approach, take the food, and retreat.
Again, this is done over a period of many weeks of several training sessions per week, and you do not ever push her beyond what she is ready for. What I've described here is a very basic, no frills version. Finding a good trainer who can walk you through this process is really your best option, because there is so much to keep in mind while doing this. Without the guidance of a skilled professional, it is very easy to do something wrong and set your training back light years. I'd hate to have you follow my suggestion, and because I have not painted a complete picture for you, have the problem become even worse. So please, see a trainer! <img src="/ubbthreads/images/graemlins/smile.gif" alt="" />