A Dog’s Nose: Why They Can Detect Odors

www.suecoletta.comIn my post, What Happens at the Body Farm? I touched on cadaver dogs. Many of you wanted to learn more about these super sniffers, so let’s find out why a dog’s nose can detect odors and later, we’ll move onto how you can print your dog’s nose, and why.

It’s no secret that dogs have a far superior sense of smell than we do. Hence, why cadaver and drug dogs have become an integral part of law enforcement. In order to fully grasp dogs’ ability to track scents, we must first look at how this is possible.

Where we rely on our sight to interpret the world around us, dogs use their sense of smell. To really appreciate a dog’s olfactory ability, let’s first examine the structure of this amazing organ.

Structure of a Dog’s Nose

Inside any nose, ours included, are bony scroll-shaped plates called turbinates, over which air passes. A microscopic view reveals a thick, spongy membrane that contains scent-detecting cells and nerves that transport the information to the brain. Our scent-detecting area is about one square inch (about the size of a postage stamp). In dogs, if we were able to unfold the scent-detecting area to its full capacity, we’d find that it may be as large as 60 square inches (about the size of a sheet of printer paper).

Though the size of this surface varies with the length of the dog’s nose, even flat-nosed breeds can detect odors far better than we can. Additionally, a dog’s brain is also made for identifying scents. The part of the brain that’s devoted to analyzing smells is actually 10 times larger than ours, allowing dogs to better identify smells 10K-100K times more accurate.

“Let’s suppose they’re just 10,000 times better,” says James Walker, former director of the Sensory Research Institute at Florida State University. “If you make the analogy to vision, what you and I can see at a third of a mile, a dog could see more than 3,000 miles away and still see as well.”

To grasp dogs’ inherent power, below is a table from the Dummies Guide that shows the amount of scent-detecting cells.

Humans — 5 million

Dachshund — 125 million

Fox Terrier — 147 million

Beagle — 225 million

German Shepherd — 225 million

And the superstar scent trackers — Bloodhound with their 300 million scent-detecting cells. Bloodhounds have an added advantage. When they track, their floppy ears sweep the air toward their nose to amplify the scent.

Real Life Superheroes

Experts have reported incredible true stories about dogs’ amazing abilities. Information gathered from Nova.

  • The black lab in Seattle who detected a floating orca scat from up to a mile away, across the choppy waters of Puget Sound.
  • The drug-sniffing dog that found a plastic container filled with 35 pounds of marijuana submerged in gasoline within a gas tank.
  • The cancer-sniffing dog who insisted a spot on a patient’s skin was melanoma after doctors had pronounced the area cancer-free. A subsequent biopsy confirmed melanoma in a fraction of the cells.

A Dog’s Nose

Our dogs’ noses have a pattern of ridges and dimples that, in combination with the outline of its nostril openings, make up a nose print — as unique as a A DOG'S NOSE: WHY THEY CAN DETECT ODORSfingerprint. There are companies that even register dogs’ nose prints in order to locate lost or stolen pets. This practice is especially popular among kennel clubs.

Dogs’ noses also function quite differently than ours. When we inhale, we smell and breathe through the same airways. When dogs inhale, a fold of tissue inside their nostril separates these two functions into different pathways.

Bioengineers at Pennsylvania State University are now working to reverse-engineer the canine nose to aid in the design of artificial noses that can detect odors as well as dogs.


In humans, the sense of smell is relegated to a small region on the roof of our nasal cavity, along the main airflow path. In other words, the air we smell releases as we exhale. In dogs, however, about 12% of the inspired air takes a detour into a recessed area in the back of the nose, dedicated to olfaction, while the remaining incoming air sweeps past that nook and down the larynx, into the lungs. Within the recessed area, the odor-infused air filters through turbinates, the scroll-shaped bony structures I mentioned earlier. Olfactory receptors within the tissue line the turbinates. These receptors recognize the odor molecules by their shape and send electrical signals to the brain for analysis.

We can’t wiggle our nostrils independently, but dogs can. This, along with each nostril’s aerodynamic reach, helps them determine which nostril an odor arrived in, aiding them in locating the odor’s source.

In addition, dogs have a second olfactory capability that we don’t have — an organ we don’t even possess. It’s called the vomeronasal organ, aka Jacobson’s organ. Located in the bottom of a dog’s nasal passage, this organ is solely used to detect pheromones. However, the pheromone molecules never mix with odor molecules or their analysis, because the organ has its own separate nerves that lead to a part of the brain devoted entirely to interpreting its signals.

Amazing, right? If any of you have ever had a dog in heat, this is why potential mates from thirty miles away littered your front lawn. And why, a wave of panic shot through your core when you envisioned them invading your house and mounting your precious baby.

Training Cadaver Dogs

Training a cadaver dog requires regular contact with human blood, decaying flesh, and bones. In the United States, dog handlers can legally obtain bodily components like human placenta and blood, but it isn’t always easy to find. Which is why trainers like Mary E. Cablk, a scientist at the Desert Research Institute in Nevada, often resort to using their own blood. Substitutes are available commercially, called ersatz odors — the most common is Sigma Pseudo Corpse Scent, which comes in three scents: recently dead, decomposed, and drowned.

However, the best way to train a cadaver dog is by using real scents at places like The Body Farm. Cablk had this to say about what type of dog is best to train: “You don’t want a really smart animal. Its curiosity might lead to distraction. Instead, look for a midsize dog that never tires of playing with a tennis ball or pull toy. Eventually, you will teach the dog to associate the smell of death with its toy by making the toy smell like death.”

“Your dog should be exposed to, and trained to find, all sorts of dead bodies — on varied terrain, day or night, rain or shine,” she said. “You have the whole gamut, from old dry bones to somebody who dropped dead from a stroke an hour before you showed up. Until proved otherwise, every area is a crime scene. Coach your dog to calmly sit or lie down when it locates a scent’s source. Digging, peeing, and frolicking can destroy evidence.”

How to Print Your Dog


Don’t let the smile fool you. My baby, Cascius, would NOT be happy if I tried this. Besides, he leaves enough prints on the glass doors to ID him a thousand times over.

But if you’d like to try to print your dog, here’s how:

Wipe your dog’s nose with a towel to dry the surface. Pour food coloring onto a paper towel and lightly coat your dog’s nose. Hold a pad of paper to his nose, but make sure to let the pad’s sides curve around the edges to pick up the full nose impression.

This may take a few tries to get the right amount of food coloring and pressure to produce a viable print. Food coloring is non-toxic and can easily be removed. I shouldn’t have to say this, but please don’t use ink or paint. Not only could you cause harm, but how would explain your dog having a blue or red nose?

Fascinating unrelated detail: Male dogs tend to use their left paw more, whereas females tend to use their right. And you know, I find this to be accurate. My dog is male and he’s definitely a lefty.

About Sue Coletta

Member of Mystery Writers of America, Sisters in Crime, and International Thriller Writers, Sue Coletta is the bestselling, award-winning author of psychological thrillers and mysteries. OOTG Flash Fiction Offensive magazine published her flash fiction and her short stories are published in numerous anthologies and collections. InSinC Quarterly featured her forensic articles about Radiocarbon Dating and Skeletal Differences. In 2017, Feedspot awarded her Murder Blog as one of the Top 50 Crime Blogs on the net. Sue's also the communications manager for Forensic Science and the Serial Killer Project. As a way to help fellow crime writers, Sue created a team of crime experts (detectives, coroners, police captains, etc.) and founded #ACrimeChat on Twitter. She's also a proud member of the Kill Zone, where she blogs every other Monday.


  1. WOW! I knew dogs’ senses of smells were amazing, but the analogy about our sight made me realize just how amazing! Thanks for sharing this information.

  2. Wow, it’s amazing!
    and i just know that GSD has 225 million of the amount of scent-detecting cells. That’s why police commonly using the breed of german Sheppard dog…
    this is great information, thanks for sharing

  3. Sue – I thought of you today when I heard this episode of the Criminal podcast. It’s fantastic. http://thisiscriminal.com/episode-29-officer-talon-10-30-2015/
    Colette Sartor recently posted…Carve Premium Edition of “La Cuesta Encantada”My Profile

  4. How amazing is this article!!!!
    Well, I never realised just how incredible a dog’s nose actually is….really impressed!
    Fabulously written, kept me entertained right to the end….thank you for sharing 🙂

  5. Love this post so much. I’ve always been fascinated by service dogs. I was at a coffeehouse once where a young woman was working on her computer with her Saint Bernard service dog lying quietly underneath the table. When someone asked what he helped her with, she said that she had a rare disorder and he was trained to scent when her body chemistry changed, signaling an attack which required her to go to the hospital. Fascinating stuff.

    I’ve done nose work with my own GSD, and though he’s easily distracted (so true that really smart dogs aren’t always the best for nose work), when he’s really into the game, I’ve seen his head whip around to follow the scent he’s following as it’s carried on a breeze. It’s wonderful to watch. And he’s got this regal alert position that kills me every time.
    Colette Sartor recently posted…Stumbling Toward OptimismMy Profile

    • Wow, Colette. “When her body chemistry changed”–incredible! I’ve always had Rotties and Shepherds, so I know exactly what you mean by “regal alert position.” It gets me every time, too. In Marred, I originally went into detail about service dogs’ abilities. Colt (One of Sage and Niko’s dogs) was training to be a service dog, but he was too smart and playful to graduate. Even though that section didn’t make it into the final version, I did show how well-trained Colt was, and how he and Ruger reacted to threats looming nearby. They’re some of my favorite chapters in the book.

  6. Loved the comparison with eyesight. It really brought it home to me how much better a dogs sense of smell really is compared to ours.
    Bun Karyudo recently posted…My Post-Wine Post WhineMy Profile

    • I was amazed by that too, Bun, but not really surprised. There’s a man who lives down the street, and he’s always struck me as “off,” if you know what I mean. My dog agrees, too. That guy can’t get anywhere near our property without Cascius totally flipping out, ready to rip this guy’s throat out if he dares step foot on the grass. Yet, he allows other strangers (UPS, FedEx, propane company, etc.) to walk up to our door. Obviously he senses something sinister about this man, and that’s good enough for me.

  7. My guide dog Trigger is (despite being a good working dog) something of a scavenger. It always amazes me how he can find an old burger box lying on the ground of interest but I guess it has much to do with his sense of smell!

  8. So incredible that they could even sniff out the cancer… I am so grateful for the ability for our two species to work together for the good of all life. Thank you for the post.

  9. Wendy Anne Darling

    Absolutely fascinating! Thanks so much for this post, Sue; it explains a lot!

  10. I’m always mesmerized watching working dogs at airports and once watched a K-9 in action. Thanks for another excellent post.
    June Lorraine Roberts recently posted…Travelling: South AmericaMy Profile

  11. #LearnSomethingNewEveryDay! Neat post!

  12. Fascinating post, Sue! I’ve been around a number of police K-9’s and never ceased to be amazed by what these guys can do. Handlers have told me that when they’re on a fresh track of a fleeing felon, the dogs are picking up on the phenones released by fear and it’s like following a trail of neon lights.

    BTw – just tested Tobi and never noticed in his 15 years that he’s always a lefty 🙂
    Garry Rodgers recently posted…ELVIS PRESLEY — WHAT REALLY KILLED THE KINGMy Profile

    • Ah, tracking the scent of fear. Very cool. In all my years having dogs I never knew if they were righties or lefties, either. Crazy, right? Dogs get more and more fascinating. I wonder what other secret powers they possess. Tobi is 15? Wow. He looks great.

  13. Dogs are really amazing creatures. I’m a cat person (don’t laugh) but I love those lovable and service-oriented canines. Your informative post makes me appreciate them all the more.
    Mae Clair recently posted…Digging Out by Mae ClairMy Profile

    • While researching this post I kept staring at my dog’s nose. (I think I was giving him a complex) But I’m amazed at their ability. And it makes me wonder about other animals, like cats. Do they have secret abilities that we’re unaware of? They’re all so secretive. 😉

  14. This is really interesting! Thank you. I like the border control inspections when the Customs person eyeballs you, but the dog quickly sniffs and moves on. They know who the real baddies are. Dogs are so clever.
    Joycelin Leahy recently posted…The Fragrant Beauty – PhotographyMy Profile

  15. I love this kind of stuff and used to have a rabbit hunting Bassett. Looks like I still have to enter a plethora of data before I can comment. Your email said this changed. Only mentioning it so you’ll know.

  16. This is absolutely fascinating, Sue. Experiencing the world the way a dog does is so different from the way a human does, and a lot of it is that dogs have different strengths. Scent and the ability to follow it and know is definitely one of them. I’ve also read that dogs can distinguish scents that are mingled together, as you get in, say, a stew. Their noses don’t say, ‘stew;’ they say ‘carrots, beef, potatoes, ‘ etc….

    • Exactly, Margot. They smell each vegetable, not the entire stew. They can also detect one teaspoon of sugar in 1000 gallons of water, equal to two Olympic sized swimming pools. Incredible noses.

      • …and cheese at incredible distances 🙂 Or my Ani does anyway…
        I’ve often wondered whether it is hearing or smell that alerts her to my younger son’s arrival ten minutes before he knocks on the door.

        • I think that’s their incredible hearing, Sue. It’s my understanding that they can hear our car engines up to three miles away. Which I believe, because my dog waits by the door five minutes before my husband walks through.

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