Substance Detectors - These police dogs also use their sense of smell to help police, but in a different way from tracking dogs. Substance dogs focus on detecting a specific substance. Some dogs specialize in recognizing bombs or explosives. These brave dogs are trained not only in detecting the explosive, but also how to respond (very carefully!) and safely let their officer partner know where the explosive is located. Other dogs may focus on illegal drugs. These dogs help save officers from having to slowly search by hand through luggage or a car or other areas by quickly determining if an illegal substance is near.