Dogs have four instinctive responses to stimuli in the environment:
fight, flight, avoidance, and surrender.
A fearful dog exhibits either avoidance or flight: they try to either actively ignore or run away from the stimulus completely. Now we don’t want to fight, which can sometimes be an extreme fear reaction this is the classic “cornered animal” attacking viciously even though it’s scared to death. We make it to surrender, which is the dog simply accepting the stimulus without having a strong reaction to it.
What should we do with the scared dog?
First You need to be in a state of quiet determination. It means you should be in a calm assertive state.
Calm assertive energy that leads a dog to surrender, and this is the proper way to approach your fearful dog with energy and actions.
A fearful dog does not need comforting and definitely does not need the human sharing in that fear. A fearful dog needs a calm, assertive leader. We can’t tell our dogs that everything is going to be okay with words, but we can definitely show them with our actions and energy.
Dogs learn by imitating, and the fearful Pack Leader (humans) will lead to an unbalanced and unpredictable dog. The dog may shut down completely in a terrified state, or she may become extremely aggressive toward anyone or anything that approaches.
So you should stay strong in all situations and be confident then only they will follow you and consider you as pack leader.
This is not happening overnight. it takes time, keep patience. It may be happening in one month or two months or etc... It depends upon the dog's nature and adaptability.