Can Dogs Smell Drugs?

Have you been through customs at an international airport recently, or maybe attended a music festival? If so, there's a pretty good chance you will have seen highly-trained sniffer dogs in action. These pooches are trained to sniff out all manner of odors, from explosives and contraband items to — you guessed it — drugs.

So if you're wondering whether dogs can smell drugs, the answer is a resounding yes. As for what types of narcotics canines can detect and just how strong a dog's sense of smell is, we'll have to put our noses to the ground and start sniffing out the details.

We all know that dogs have an amazing sense of smell, and watching a canine put its remarkably powerful honker into action is a wonderful sight. Of course, most dog owners will be familiar with the signs that their dog has picked up an interesting scent that they just "have" to track down. 

The first indication is often when your furry friend starts completely ignoring anything you say and everything that's going on around them and sets off in a seemingly random direction. With nose on the ground or in the air, working frantically to inhale and exhale quickly, your pooch sets off in pursuit of a tasty morsel, another dog's odor, or anything else that happens to pique their interest. 

Your calls to "stop" or "come back" are usually summarily ignored until your pet has satisfied his need to track down and explore whatever his schnoz has detected.
In the case of professional sniffer dogs that work for the police, customs and other law enforcement agencies, these animals are trained to perform a specific behavior when they've detected a narcotic they're trained to sniff out. This usually takes the form of sitting next to the object or person on which they've picked up the telltale odor, so even the most avid dog lover definitely wouldn't want a cute detection dog plonking its behind down next to them at the airport!

Dogs have been used in law enforcement since the 14th century, but our canines were typically used more for their guarding and hunting prowess than their nifty noses. However, London's Metropolitan Police Force used Bloodhounds to track suspects during the notorious Jack the Ripper investigation in the 1880s, while the US military used bomb dogs to detect German mines in North Africa in World War II.

By the 1970s, US law enforcement agencies had started using dogs to detect a range of illegal substances, including marijuana, heroin, cocaine, and crack cocaine, as well as to sniff out explosives. Ecstasy and methamphetamine were later added to the list of substances police sniffer dogs were trained to track down.

In recent times, sniffer dogs in some parts of the country have had to undergo some re-training to adjust to changing laws and regulations. For example, following the legalization of marijuana for recreational use in Washington in 2012,  police departments were forced to put their canines through pot desensitization training and make plans to not train future dogs to detect marijuana. Of course, those dogs are still more than capable of detecting a whole range of other illegal substances whenever the need arises.

The dog's astounding sense of smell has been the subject of much scientific research, so we know quite a bit about why canines are so much better at detecting drugs using just their noses than us humans are.

Our dogs use their wet, spongy noses to capture scents, and exhale through slits in the side of the nose in a fashion that helps circulate new air through the nostrils. Some breeds that are famed for their sniffing ability, such as Bloodhounds, also boast long ears that act almost like brooms, sweeping smells upwards and into their nostrils.

Once the air enters the nostril, it encounters a fold of tissue that diverts the air along two separate channels — one is used for breathing and the other route is used to analyze scent.

And then comes the part where our canine companions really put us in the shade. Dogs have up to 300 million olfactory receptors in their noses; we only have around 6 million. The part of a dog's brain responsible for analyzing smells is, proportionally, 40 times greater than our own, all of which ensures that dogs have an acute sense of smell that is anywhere between 10,000 and 100,000 times better than ours.

If a law enforcement dog can smell drugs, that doesn't mean he's addicted to them or loves their taste or smell. Instead, it means that canine has been trained to understand that if he tracks down a target odor, such as cocaine, heroin or methamphetamine, he'll get a reward. Depending on the dog, that could either be a food reward or some play time with their favorite toy.

Training a drug detection dog takes several months and focuses on teaching the dog to identify and find specific illegal substances. Dogs are taught the confidence to search in a wide range of settings, scent association, and search patterns, with rewards used every step of the way to encourage desired behaviors.

The breeds most commonly trained to act as sniffer dogs include Labradors, German Shepherds and Belgian Malinois. Not only do they possess a steady temperament that allows them to search in all manner of new environments, but they also have a strong prey drive that motivates them to seek out whatever they've been tasked with finding.