Here is a link to a good article that discusses fears your dog may develop and how to overcome them. HINT: Treats will be involved! The article discusses the genetics, physical health, and early life experiences that cause dogs to develop fearful behaviors.
Chances are good that at some point with every dog you'll have the opportunity help the dog overcome a fear. Some dogs go through most of their lives with barely an apprehensive moment, and then get hit hard in old age when their bodies begin to fail and they don't know how to cope. Now you know how to help your dog develop the ability to cope, at any age