Police dogs are trained to be an aggressive but obedient member of the police force. This can be a tricky combination. Many of the dogs come from a hunting and herding class. They are valued for their keen sense of smell, which is valuable for tracking suspects or drugs and for search and rescue.
As the most popular police dog breed, the German shepherd is prized for its strength, obedience, eagerness to learn, confidence, alertness, cheerfulness and courage. They were originally bred as herders but were used in World War I as messengers that carried information to soldiers. The dogs also smelled enemy forces before army officials could detect them. Their performance in the war got the attention of American police officials who trained the dog to be a part of the police force. German shepherds have a keen protective instinct and must be trained to obey from an early age.
Labrador retrievers are known for their good temperament. They are eager to please, making them an ideal candidate as a police dog. These dogs stand out from other police dogs because of their ability to swim, and they don't hesitate at jumping into icy water. They are commonly used at airports to sniff out narcotics. Labrador retrievers act quickly and courageously in an emergency. The breed is also a common guide dog.
Rottweilers are extremely strong dogs, with a huge muscular body and intimidating stare that is accented by their round forehead and sharp teeth. Their strength is matched by their intelligence and some police officers prefer them over German shepherds. Rottweilers are divided into German and American breeds. The German breed is shorter and stockier with a broader head than its American counterpart. Like other police dogs, the Rottweiler is devoted to its owner.
Like the German shepherd, doberman pinschers gained popularity after their successful use in WW I. Several thousand of these dogs were trained for action in the war. While they aren't as commonly used for police work as German shepherds, they are valued for their obedience, loyalty and quick reaction. Doberman pinschers are often depicted in movies as snarling guard dogs. But according to Dog and Kennel magazine, they learn their aggression from humans.