article image

Anatomy of a Dog Snout as Viewed by The Caninologist

The Caninologist

A dog’s snout has 300 million sensors. Someone actually calculated this, and confirmed it’s neither 200 million nor 400 million but 300 million. On the other hand, if you said a dog snout has half a billion sensors, you wouldn’t be too far off.

Humans have only 5 million sensors. A dog’s nose is estimated to be 100 million times more sensitive than a human’s, give or take an order of magnitude or so.

That’s according to Secrets of the Snout: The Dog’s Incredible Nose, a 2018 book by Frank Rosell, a Norwegian professor who knows a ton about dog snouts.

At birth, a puppy’s nose is well designed to find nourishment. The snout has 5,000 heat sensors. That’s according to a blurb on a sack of dog food somebody delivered the other day. If anyone can confirm this, please let me and Dr. Rosell know.

In nearly all cases, a dog will go where its snout points. The typical dog snout is many times — maybe a thousand times — more sensitive than a typical human’s. And yet they still eat that stuff.

Dog heads have complex structures and airways inside their noses that underlie their sniffing skills. Deep back of the nostrils, everything comes together in the twisted “olfactory recess.”

This structure, which acts like a sponge for air and odor molecules, takes up a large amount of space. It contains no brain. Dogs have a hole in their head. All the twists of the nasal passages that make up the olfactory recess create surface area to accommodate all those sensors.

Dogs sniff five times a second. They pant at the same pace.

Many years ago, I wrote a newspaper story about human laughter, and how chimpanzees laugh differently than humans because the chimps generally walk on all fours, and we walk on two legs. This may also explain why dogs don’t really laugh like us, either. But they do laugh at us.

Scientists in 2009 attached some special muzzles to dog subjects to model how sniffing works. Among other findings, they learned that each nostril acts independently of the other, which helps dogs track where a scent is coming from.

Some humans can wiggle one nostril at a time. Each nasal passage is separate from the other. But we smell with both nostrils at the same time and that’s that.

Dogs lick their snouts a lot. They like to keep them wet. Smells soak in better, maybe.

A new study out this year discusses an artificial nose — aka “volatile organic chemical analyzer” — in action. This one was deployed to tell the difference between a disease-carrying dog in Brazil and a non-disease-carrying dog in Brazil. It worked with 95 percent accuracy.

People have taken nose prints of dogs. They are kind of like fingerprints only with more mucus, usually. But no dog has yet been convicted on this basis.


Carl T. Hall is a longtime union organizer in San Francisco who is now a co-owner of Word A Café, a dog friendly coffee shop now open for business in the Bayview Neighborhood. Readers can pick up copies of Bay Woof there, too.

Main article photo by: Photos by CC