I am bound to hear a lot of aguments about this one: I took a 12 month old puppy that could not be sold. She was so timid she was standing against a wall when I saw her and would not move. She thought that by not moving no one would see her. I grabbed her and carried her to the car and took her home. I crated her with water and food dish and left the door open. I stayed in the room with her as much as possible and would have to gently drag her out of the crate for the washroom breaks. It took weeks before she would come out on her own. Then she would come out of the crate to chase me and play catch me as I ran around the floor on all fours, LOL.
It took longer to get her to explore the house, and when ever any other house member came near, she would run back to the crate.
I brought to a guy who trained many search dogs, by the use of food and toy praise )which I do not agree with anymore). She showed her timidness and no desire to have interest in anything or rewards.
He blew her off as a worthless fear dog, with no work potential. I told him he was wrong. A couple of months later, I showed up with her when he was working dogs and lots of people around and she had more drive to work than most of the other dogs.
The only thing I did that made this dog was this: First I built her trust in me by becomming a playmate who did not hurt her. Then I forced her to exposure - not in a way most of you would appreciate.
We had a rescue (not me, but our police force) a guy had fallen over a cliff. Air rescue (helicopter), firetrucks and cruisers where everywhere. I was walking the dog in the bush when it happened. I took her to the area and she crept into the bushes and hid. I tugged the leash to get her on her feet and she refused. I gave her a few chances to listen to my command to get up and then I made her get up.
The first few feet meant dragging her by her leash. "Then the bells in her head went off", she realized I was boss and I had never harmed her, and she walked along happily right past all the commotion. Sounds mean, but it had to be done. From that point on she was great and brave. It may not work with other dogs, but it was something I knew was deep inside of her waiting to come out. From that point on she learned tracking and air scent even during a kids soccer game with a packed field of parents and kids. She acted like they where not even there.
Sometimes you have to either let them continue in fear or take the chance and reach in and force the fear away. If the dog continues in fear, then he always will.
Just my opinion. It doesn't mean I am right.