Try to be calm when you approach the dog, and approach it indirectly. Do not speak, do not look straight at it, sidle up to it from the side (not head on), and see if that helps. Another alternative is to hold out a treat and get the dog to come to you instead of you to the dog. Again, don't move too quickly or aggressively when you go to pick her up, and try to approach from the side. Try to imagine what you would do if approaching a skittish horse, and move accordingly, i.e. slowly and cautiously without any sudden surprises.