How do you gain the trust of a 'fear biter"

In addition to the positive reinforcement training (giving her food that she is interested in when she does a behavior you want to see more of, like eye contact) you might also see if the shelter has a foster care program. Changing the environment can have a very strong effect on how an animal behaves. Think about the difference between being on stage, or being at home in front of the TV.

doggie treats. Talk to her and toss doggie treats alittle at a time. No telling what shes been through. Sit with your back to the cage (if you have the time)and just wait. Toss some trets and wait. When she comes to smell you don't move let her sniff,when she moves back toss her a treat. Hold your hand up to the fence(don't put it in) let her sniff talking very softly. See if that works.

The worst thing you can do is to feel sorry for her. I know it's hard but to a dog pity means weakness. If a dog senses weakness in others ( human or animal)it either becomes prey and is attacked or is not respected. You need to be absolutly calm and assertive. Do not try to touch, give no eye contact and but try to sit as close as you can with your back to her. Let her come to you. She'll probably sneak up an try to sniff you. Still be quiet and still. When the time comes and she starts to relax a bit. Try touching a leg and work your way up to the chest. Stay away from her head until she learns to trust you. Walking a dog is the best way to bond with any dog. The more she fears something( like noise) the more she needs to confront it with your help. Remember,do NOT give affection when a dog is under stress. If you do you are reenforcing that fear. Give praise only when the dogs is quite and submissive.

We had several shelter dogs like that while eat one is not the same our most recent dog Artie was very fearful. We couldn't get 5 feet near him without him coming after us. Glad there was a fence between us or he would have bitten many of us. What we did and our trainer told us to do is crouch down side ways with your head down. Do not make eye contact with her. When she calms down and stops attacking pop her a treat in her cage. Have everyone do it. Then slowly add in good girl in a happy tone when she doesn't go after you. The moment she doesn't fear out pop her a treat but always stay low and make no eye contact. She'll soohn learn that good things come and are happening. It takes a little while but it does work. End everything on a positive note. She'll soon learn your not going to hurt her. Artie as days past got better and better. He also loved walks so once he got to the point where we could stand in front of his cage good things where still happening ( giving him treats on good notes) he soon started getting exctied when the other dogs went for walks and started to act as he wanted to. So we slowly worked towards getting a slip leash on him and before long anytime he saw a leash he was your bst friend. It takes time but they do come around. Just remember to never make eye contact not until she starts trusting you. Artie was adopted out and so will your little fearful girl. Start slow and stay low lick your lips if you have to that works too. Just go slow and stay low until she feels safe with you.