More realistically the cause of a dog’s wariness or fear of a certain type of person or event is due to their lack of experience with it. This behavior is normal. Any one of us would startle were a space ship to land on our front lawn, and the safest response to have might be to run in the house and lock the door until we knew the aliens were safe.
The first 5 months of a dog’s life are crucial in their development. It is during that time when exposure to novelty will play a huge part in the dog’s future ability to cope with changes in their environment. Many stray or street dogs have had the advantage in this because they were not confined to a cage, kennel or backyard where there was limited stimulation. Though they have developed a nervous system which is resilient to change, the objects they have been exposed to have likely been limited. Overhead fans, trash cans, toddlers, women with rakes, may scare them.
Dogs going through transitions (going into a shelter, then into foster care, then onto a transport, then into their new home in a new part of the country, losing all their familiar social companions) are already experiencing high levels of stress and each additional straw tossed on their back is possibly going to elicit a stronger response.
When you see your dog show fear of a new object, event, or person, the dog needs to feel safe. We do this by allowing the dog to move away from what is of concern, and give them something to make them feel good. If every time a man with a hat walked by and a piece of cheese fell from the sky, it won’t be long before the dog sees men with hats in an entirely different light.
When we learn that our dog struggles with particular people or events we can be prepared to help reframe the picture for them. If you need help or ideas for how to do this with your dog a skilled rewards based trainer can show you how.