A Lady phoned me last night that has a 5 month old Bloodhound a dog that you don't hear about or see much anymore in the UK.. Still used for tracking by the police in the USA but on the endangered species list here in the UK. Her queries were that her dog at 5 months had become fearful of everything. As a young puppy her dog was well socialized with everything and everyone, even the postman came in and had a cuddle. Her puppy had never been attacked by another dog and had a nice solid start in life. So whats gone wrong now, the dog now hides from the friendly postman and is scared of parked vans and people with hivis jackets etc. Think about a baby who is passed around the family, people leaning over the pram saying hello lots of cuddles with the family etc. All very much like the young puppy all is great in the world for the baby and the puppy. A human baby will go from strength to strength and hopefully socialize well and live without fear of anything. Its in our genes, that is how we are. This is not the case for some dogs however, a dogs genes work differently to ours. At around 5 or 6 months survival kicks in to the dogs brain where everything is seen as a threat to the dogs life and for no apparent reason to us the dog develops fight or flight. This is where care needs to be taken in training. Trust is the most important thing between dog and owner. Get your dogs trust and the fears will disappear.