A K9 or K-9 are specifically trained dogs to assist law enforcement and military personnel. They're trained to assist in various duties, such as searching for drugs and explosives, locating missing or wounded people, finding crime scene evidence, protecting officers and other people, detecting enemy or intruders, and chasing and subduing fleeing suspects.
The breeds most commonly used by law enforcement and the military are the German Shepherd, Belgian Malinois, Bloodhound, Dutch Shepherd, and Labrador Retriever. Rottweiler and Doberman Pinscher were also common breeds early on, but have since fallen out of favor.
