Working Dogs

No dog is genetically programmed to recognize the scent of narcotics, but any dog trained for detection work can learn to sniff for drugs. Dogs have at least 200,000 more olfactory receptors than humans do, so even substances we consider odorless can waft a powerful whiff toward a dog's nostrils. In the U.S., the Transportation Security Agency, the Federal Aviation Administration, the F.B.I, and Customs officials all depend on dogs to locate an ever-increasing selection of illegal narcotics quickly and without bias.