When a police dog is injured or retires, replacing that dog costs thousands of dollars. Police use dogs that are specifically bred for police work..
Police departments in Minnesota get their dogs from Eastern Europe -- where they are bred with specific traits like psychological stability and a drive to work. Once they arrive in Minnesota, the dogs and their handlers have to go through at least 12 weeks of intensive training.



More at the link, with video:

http://kstp.com/news/stories/S2030007.shtml?cat=1