Police dogs can be trained to detect a variety of items through smell, depending on the needs of the specific law enforcement department in which the animals work. Common things that these dogs can be trained to sniff out include narcotics, explosives, blood, weapons and dead bodies. In 1997, the US Secret Service trained its first canine to detect the scent of the most commonly counterfeited US money notes. A police dog also can be trained to detect a scent of a particular human, which might be used to find a missing person or a suspected criminal. Dogs are thought to have a sense of smell that is at least 10,000 times more powerful than that of human beings, and they have the ability to filter separate scents.
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