Professional working K9s are highly prized for their ability to detect and alert to a wide range of target odors including, but not limited to, drugs, explosives, cell phones, money, cancer cells and bed bugs. While everyone knows a dog's nose is far more sensitive than our own noses, the whats, whys and hows aren't nearly as clear. Learn more about the inner workings of a K9's range of smell to better understand the dogs and handlers that work to ensure safety, security and health.
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When people say, "My dog's nose is wet," they're normally talking about the part of a dog's face at the end of their muzzle. While that is part a dog's nose, it's just the tip of the iceberg. Just behind the external part of a dog's nose lies a circulation chamber. A dog pulls air in through his nostrils (the black or pink part at the end of a dog's muzzle) and from there, the air circulates through a cavity above the roof of the mouth. After the dog has gathered all the information from the air he can, it continues to the "olfactory recess," a specialized structure formed of tightly folded airways. After passing through the airways, the dog exhales and the air passes back through the circulation chamber and exits the dog's body. The scent itself is retained in the olfactory recess. Nestled throughout a dog's entire muzzle are nerves leading directly to the part of the brain responsible for scent identification, processing and storage.
A dog has 220 million olfactory receptors in his nose whereas a human possesses approximately 5 million. When an odor enters a dog's nose and circulates through the olfactory recess, it passes through, over and around those 220 million receptors, many of which are connected to nerves leading directly to the olfactory lobe of the brain. Compared to most other species, the olfactory lobe in dogs is massive and overdeveloped. Once a dog has processed a scent, it'll be stored in the olfactory lobe and he'll remember it for the rest of his life.
A dog uses his scent memory bank to connect specific scents to specific situations so he knows how to respond. For example, when an unaltered male sniffs a female in heat, he automatically begins a mating ritual. A drug K9 who smells his target odor alerts to it so he can receive his reward. A dog who smells dinner cooking begins to beg on the off chance a tidbit will come his way. A dog on a walk sniffs lamp posts, fire hydrants and plants to gather information about other dogs in the area and determine if they're friend or foe.
Most researchers agree that a dog's nose is 10,000 to 100,000 times more sensitive than a human's. With the unique anatomy of a dog's nose, that degree of sensitivity allows a K9 to smell a substance diluted to 5 parts per trillion. As an example, a dog possesses the ability to detect a single teaspoon of sugar dropped into a million gallons of water.
While all dogs sniff things, it takes specialized training to teach a dog to zero in on and alert to specific odors. Using a system of rewards, trainers teach a K9 to mentally link the scent of the desired substance with his favorite reward. In the dog's mind, the presence of a certain scent, perhaps drugs or a cell phone, automatically produces his toy or a special treat. Through a specialized training regimen, K9s are taught to alert only to certain scents, to ignore other odors that smell just as enticing and to alert consistently and predictably.
By Kea Grace
PBS: Dogs' Dazzling Sense of Smell
Whole Dog Journal: The Canine Sense of Smell
Auburn University: Canine Detection Capacity
Science NOW: The Secret of a Dog's Sniffer
ACES: The Dog's Sense of Smell
Seattle Police Department: Scent -- K9's Reason for Being
Police K9: Theory of Scent
About the Author
Since 2001, Kea Grace has published in "Dog Fancy," "Clean Run," "Front and Finish" and an international Czechoslovakian agility enthusiast magazine. Grace is the head trainer for Gimme Grace Dog Training and holds her CPDT-KA and CTDI certifications. She is a member of the APDT and is a recognized CLASS instructor. She's seeking German certification from the Goethe Institut.