Sniffing Around: 5 Dog Nose Facts

Did you know that dogs smell in stereo? Did you know that a dog’s nose print is as individual as a human’s fingerprint? A dog’s nose is an amazing thing. In the book, K9 Scent Training by Resi Gerritsen and Ruud Haak, two of the leading specialists in identification, tracking and detection-dog work, the authors cover the science of odors and how dogs perceive them. The book is also replete with interesting facts and insights, some of which we’re including here.

Dog Nose Facts

Here are five surprising facts about a dog’s nose that you might not know.

• Dogs Smell Fear. It’s true! A study published in 2017 confirms what many people already knew, that dogs can smell fear, and they’ll mirror the behavior too. In the study, Golden Retrievers and Labrador Retrievers were exposed to neutral, happy, and fear odor samples. The dogs displayed more stressful behaviors when exposed to fear smells than happy or neutral smells. With the fear odors, dogs would seek reassurance from owners, make less contact with the “stranger” in the room, and had higher heart rates.

• Feet first. What human body part has the most sweat glands per square centimeter and produces the signature odor that dogs use to track us? If you guessed feet, you’re right.

Feet top the odor chart; sebaceous glands on the soles, sides and top secrete fats and cellular debris that, when mixed with bacteria and fatty acids, produce a scent that drives ’em wild. Even shoes don’t hinder transmission of the odor; it penetrates whatever is between it (sock, insole, shoe) and the contact surface (pavement, grass, sand).

No matter what we’re doing, our feet produce a constant stream of smell and that’s one reason why dogs love feet. And, good to know, worn shoes are “especially good at spilling foot odor,” so if you’re thinking of making a quick getaway, get yourself a new pair of sneakers.

• Girls rule. According to the authors, when it comes to the sex of the dog and how good the dog is with scent detection, “It has long been known that females have a better sense of smell than males.” So why are K9 officers predominately male? Seems like the females’ smell, especially when in heat, is distracting to their male coworkers. So, while spayed females retain high marks in detection work, the higher pay scale jobs goes to the males.

• Sniff rate. A dog breathes in and out around 15 times per minute when sitting calmly. That frequency goes up to 31 times per minute while walking. But when a dog is actively sniffing, the inhalation/exhalation rate goes up to 140 to 200 times per minute.

Hunting dogs and other detector dogs employ a technique called “air scenting”: one very long inhalation (lasting 20 times longer than a normal sniff), followed by an exhalation through the mouth. This transfers a huge volume of scent up their noses into their olfactory epithelium, which is directly responsible for odor detection.

• Humans have the knack, too. Dogs have 125 to 300 million olfactory cells (compared to our 5 million), and 33% of their brain is dedicated to interpreting odors. While we have far less sniffing talent than dogs, researchers have found that with a little practice, we can get better at odor detection.

For example, study participants have been able to detect fear in human sweat as well as pick out our their own T-shirt in a batch of 100 identical shirts. In one study, two-thirds of the participants were able to follow a 33-foot-long scent trail of chocolate oil even though they were blindfolded and wore gloves and earplugs. They did it by smell alone.

• Nose Greetings. Female dogs are more likely to greet other dogs by smelling the snout/muzzle first, while males go for the anogenital region. (You might be able to sex the dogs who greet your dog based on this behavior alone.)