The use of working dogs for various purposes, such as herding or hunting, goes back for centuries. Their use in law enforcement goes back only to the early 1900s, but continues to become more widespread. Police dogs can be expensive to buy and train, but police departments across the country have found that they have many advantages.
Drugs and Explosives
Dogs have a keen sense of smell and can detect odors that humans cannot. With proper training, a police dog can detect certain items even if they are sealed in plastic or buried in something intended to mask the scent. Dogs are routinely trained to detect the scent of various drugs, such as marijuana, cocaine and methamphetamine. They can also be trained to search for flammables and explosives, and to provide legal grounds to establish probable cause for a search.
The dog's sense of smell is also used for tracking people on foot, either for criminal apprehension or in search-and-rescue situations. Tracking dogs may be either trailing dogs or air scent dogs. Once given something with the scent of the targeted person, trailing dogs can follow the path of that person, smelling the microscopic skin cells shed along the way. Air scent dogs work by picking up human scents that are drifting in the air. This makes it possible for the dog to follow a fleeing suspect or help locate someone hiding in a building or other area.
All police dogs are protective of their handlers, and will attack if their "partner" is in danger. Patrol vehicles used by K9 officers can even be fitted with special remote control door devices, allowing the handler to release his dog without returning to the vehicle if he is in trouble. Police dogs can also be trained to work with a handler in crowd control situations.
Police dogs have the advantage of greater speed than their human counterparts, and can be trained to stop fleeing or violent suspects. On command, the dog will chase and tackle someone who runs, and if the suspect continues to fight, the dog will bite and hold until ordered to release. Careful training is required to ensure that the dog does not bite if the suspect is complying with an officer's commands.