Can Dogs Smell Edibles?
The short answer is that dogs have a sense of smell up to 100,000 times more sensitive than a person's, so a dog smells nearly everything, but typically only responds to specific scents that are of interest to them. When police dogs are in training, they are trained by positive association to alert humans when they smell specific scents, and can be trained in this way to alert for a huge range of scents.
So the real question is not “can dogs smell edibles,” since we know they can, but what do they do when these smells are detected?
A Dog's Amazing Sense of Smell
When considering whether dogs can smell edibles, it's good to remember that, while a dog's sense of smell is exponentially better than a human's, many breeds have sharper senses of smell than others. Generally speaking, humans have about 6 million scent receptors in their noses, while dogs have up to 300 million.
In addition, human noses are physically constructed to smell and to breathe at the same time, and when we exhale, we “blow” scent out of our noses. Dog's noses separate breathing functions and devote a whole channel simply to scent receptors, and exhaled air doesn't interfere with the act of smelling. In fact, dogs take in scents continuously, regardless of respiration.
Finally, dogs have a vomeronasal organ at the base of their nasal passages, which humans lack. This special organ is attuned to gathering and interpreting pheromones in scents.
Despite these incredible biological advantages, some dog breeds have definite advantages in detecting scents. Dog breeds with the best noses are:
Bloodhounds have 300 million scent receptors, more than any other breed, and can follow scents on the ground and in the air.
Basset hounds were bred to follow scents on the ground, and their long ears and droopy chins direct smells upward, trapping them near their noses for greater accuracy.
Beagles are famously used to detect contraband food items, and a well-trained beagle can identify up to 50 different odors with 90% accuracy.
German shepherds have 225 million scent receptors, and are best at detecting scents in the air.
These good-natured dogs have an excellent sense of smell, and are frequently employed in drug and bomb detection, and search and rescue operations.
Specially trained drug-sniffing dogs can scent selected drugs in an environment for up to 48 hours after the drugs have been removed.
How are Drug-sniffing Dogs Trained?
Training a drug-sniffing dog is time consuming and detailed, and only some dogs have the personality for it. Training capitalizes on a dog's natural desires to hunt, to play, and to please their human companions. If a puppy doesn't show much interest in those activities, they probably don't have the natural proclivity to be a drug sniffing dog.
Drug sniffing dogs are trained by playing a fun game of tug-of-war with their human handlers. The game is played with a towel, that is carefully washed and maintained to have no scent of its own. Eventually, the towel is exposed to marijuana, until the dog begins to naturally associate the scent of the drug with the smell of their favorite toy, and to be rewarded with play time when they find the scent.
Over time, the towel may be exposed to other drugs or desired substances, so that the dog is motivated to find particular scents. In short, the dog has no real interest in the smell of drugs, and doesn't want the drugs for their own sake; the dog is consistently rewarded for finding that scent and having a good game afterward.
It is worth pointing out that humans require training that should be even more extensive than the dog's. Critical studies show that many drug-sniffing dogs are often responding, not to the scents they detect, but to non-verbal cues by their handlers. It is crucial that the dog's human handler be well-trained, professional, and impartial.
Do Drug-sniffing Dogs Smell Edibles?
In scientific studies, drug sniffing dogs can find drugs in just over 1 minute, with 87.7% accuracy and only 5.3% false positives. These dogs are best at identifying marijuana, hashish, amphetamine, cocaine, and heroin, in that order.
The act of cooking marijuana changes the chemical composition of the compounds, and therefore alters the smell. This means that drug-sniffing dogs who are trained to alert officers to the presence of uncooked marijuana may not alert for this different scent; they would need to be trained to alert for the new scent of edibles. Most drug-sniffing dogs are not trained to alert officers to the presence of edibles, even though they could be.
The materials that dogs are trained to alert for are often requested and always regulated by the DEA. Training a drug-sniffing dog is a time consuming and expensive process so, in the absence of an initiative from the DEA, it is unlikely that dogs will be trained to reveal edibles. With the increasing legalization of marijuana in North America, it is particularly unlikely that a police department would invest the time and energy in training a dog for edibles.
In other words, yes, dogs can scent marijuana edibles. But drug-sniffing dogs are unlikely to react or alert to that scent, without specialized training. That kind of specialized training isn't currently widespread and, with the ongoing relaxation of marijuana laws, it is unlikely to be introduced. However, when traveling with edibles, it is wise to always review your local laws and follow the local possession limits.
Remember that transporting marijuana between US states, even if it is legal in both states, is still a violation of federal law, since transportation across state lines falls under federal jurisdiction. For that reason, also remember to not take any marijuana to federal sites like national parks, or mail it through the US Postal Service. Even though it is unlikely that a drug-sniffing dog will identify any edibles, you should always travel legally with marijuana, and taking steps to conceal or smuggle it creates more legal jeopardy than simply being caught with it.