A few years ago, in Bozeman, Montana, a brain surgeon and his wife were walking through a farmers’ market when they came across a booth selling dogs. The breeder, called Svalinn, touted them as a one-of-a-kind hybrid: military-grade protection dogs with elite danger-sensing instincts but the warmth and temperament of a conventional family pet. The surgeon, Regis Haid, took a closer look at the dogs, which did indeed seem magnificent, intelligent, and powerful. Then he saw the cost: at least $150,000 each.