Drug-sniffing dogs can smell sealed narcotics. Drugs have a strong smell. For example, heroin contains acetic anhydride, so it has a sour taste. During the processing of methamphetamine, in order to increase the taste, spices are usually added, so ordinary methamphetamine has a milky flavor. Drug-sniffing dogs that are sensitive to odors can smell the presence of drugs at close range.

In addition, in order to keep drug-detection dogs excited and active about special smells, they usually use reinforcement Establish a stable conditioned reflex, and over time, the drug detection dog will become more sensitive to this smell, thereby achieving the purpose of training.