Let Your Dog Sniff

By Dr. Kasandra Garner

Many of us who love our dogs often wonder what they are thinking. Perhaps we would gain more insight into their minds if we wondered, “What are they smelling?”

Alexandra Horowitz, in her new book “Being a Dog,” says that all dogs have the ability to create "a picture of the world through smell." This is partly because of the design of their snouts. Each nostril is controlled separately, allowing the dog not only to detect a particular smell, but also to locate it in space.  

A dog’s nose allows them to get a different odor sample with each nostril. Most dogs also have a long snout, which humidifies and filters the air as it delivers it to the back of the nose. At the end of the nose, right between the eyes, both dogs and humans have a little patch of tissue called the olfactory epithelium. This is where receptor cells sample the odors and send them to the brain. The dog has hundreds of millions more receptor cells than humans do.

Dogs also “sniff” differently than people do. Researchers looking at the fluid dynamics of air flow found that dogs inhale through their nostrils but exhale through the side slits of their nose, so that the inhaled odor molecules stay in the back of the nose longer. Dogs also breathe in a circular motion, which creates a little puff of air on the ground that stirs up even more odor molecules to be sniffed. This is why your dog sticks his nose so close to what he is smelling.

Dogs can tell time through smell. Strong odors are newer odors, laid down more recently. A weaker odor is something that was left in the past. So a dog can smell not only the moment, but the past. They can also detect in the air what’s coming around the bend, so in a way they can also smell the future.

Because of their amazing odor-detecting ability, dogs are used in all sorts of work. They are used to find drugs, explosives, missing people, goods that are brought into the country illegally, even illicit cell phones and computers. They can be trained to provide assistance to diabetic owners by detecting changes in breath odors that indicate abnormal blood sugar levels. One of the newest areas using dogs’ smelling superpower is cancer detection. Some dog owners noticed that their dogs were persistently sniffing an area of the owner’s body. When the owners went to the doctor and got checked out, the areas turned out to be cancers such as melanoma and breast cancer. Since that discovery researchers have now realized that dogs are able to detect various cancers on the breath, in urine, in blood and on the skin.

But back to our own dogs, who sometimes annoy us with their constant “stop and smell the roses” approach to their daily walks. Horowitz warns that pulling dogs away from smell-rich environments, such as fire hydrants and tree trunks, can cause them to lose their predisposition to smell. When dogs are living in our visual world, she says, "they start attending to our pointing and our gestures and our facial expressions more, and less to smells."

Horowitz recommends letting your dogs go for “smell walks.” Let the dog choose the direction, and let her just hang out with her nose to the ground, smelling her world. Remember that although people primarily interface with their environment visually, dogs do so “nasally”. The same way we like to stop and take in a beautiful mountain view or watch a hawk soar on thermals during a walk, dogs want time to stop and savor all of the odors on the breeze.

Walking my dogs through the neighborhoods of North Asheville after moving back, I found myself wondering if they could smell any trace of the two dogs I used to walk on these same streets when I lived here 20 years ago.  When I walk through this neighborhood now, certain sights will make me grow nostalgic. Perhaps dogs also grow nostalgic when they catch a whiff of a familiar smell -   the lingering smell of a now deceased companion or a cedar smell that reminds them of the shavings in their whelping box. We can never know exactly what is going on in our beloved dogs’ minds, but thanks to books like “Being a Dog” we can understand more about how they experience the world and how we can make it the best experience possible.

Alexandra Horowitz, the author of the lively, highly informative New York Times bestselling blockbuster Inside of a Dog, explains how dogs perceive the world through their most spectacular organ—the nose—and how we humans can put our under-used sense of smell to work in surprising ways.

To a dog, there is no such thing as “fresh air.” Every breath of air is loaded with information. In fact, what every dog—the tracking dog, of course, but also the dog lying next to you, snoring, on the couch—knows about the world comes mostly through his nose.

In Being a Dog, Alexandra Horowitz, a research scientist in the field of dog cognition and the author of the runaway bestseller Inside of a Dog, unpacks the mystery of a dog’s worldview as has never been done before...


Great insight and interested in reading "Being a Dog" and "Inside a Dog." Love hearing Dr Garner's perspective. Good reminder to enhancing my relationship with my Brother Wolf rescue Bullet.