Some police departments do accept donated dogs. However, the process of selecting a suitable dog for police work screens out most pet and show-line dogs bred in the United States. Many police departments obtain their dogs from vendors who provide specially bred and pre-screened working dogs.
Most dogs, even those from working lines, are not suitable for police work. The dog must pass a stringent temperament test, have good prey drive and be physically healthy. An estimated 25 percent of working-line German shepherds have physical faults that prevent them from being candidates for police work.
As more police departments in the United States are exposed to specially bred imported police dogs, donated American-bred dogs are becoming less attractive.