Hi I have three border collies a 13 year old a 1 year old and a 6 month old pup. The pup I have was also a rescue he was kept in a shed with no interaction. He was extremely anxious and timid at first and would cower when a hand came anywhere near him. But with plenty of walks play and rewards he is slowly coming out of his shell I also took him to dog training whitch gave him confidence. I was lucky that I had other dogs at home whitch helped him feel more at home as he was kept with another dog previously. I know at 18 months this may take a little longer but the end result will be well worth it. Border collies are a lovely breed of dog. Good Luck and hope all goes well.