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A Dog's Nose Can Detect Disease, Disaster, and Death

Schatzie has bachelor's degrees in animal science and English and a master's in education.

A Dog's Nose Can Find Disease, Disaster, and Death

A Dog's Nose Can Find Disease, Disaster, and Death

Why Are Dogs Used for Their Sense of Smell?

Dogs are known as man’s best friend for several reasons: they offer warmth and companionship, unconditional loyalty, reliable protection, and they have fantastic noses. They are capable of smelling scents with a 10,000- to 100,000-fold superiority over human abilities and can detect odors present in the air in parts per trillion.

In essence, a dog could detect a rotten fruit among two million bushels. Their noses allow them to claim territory, interact socially, detect danger, and find food. And, their noses help us to live life a little easier and a whole lot safer.

Anatomy and Physiology of the Nose

We have approximately 6 million olfactory receptors within our noses. Dogs have 300 million, and the section of their brain responsible for scent analysis is 40 times larger. When we breathe in, we simultaneously inhale air for oxygen and for scent detection through the same pathway. Smelling takes place at the roof of our nasal cavity, where all air enters and exits on its way to and from the lungs.

Bioengineers have discovered a different method used by dogs: A fold inside the nostril divides air into two pathways, one devoted to smell and the other to getting oxygen. The smelling route traps 12% of the air in the back of the nose where its odor is analyzed. The rest of the air goes on to the lungs so the dog can breathe. By isolating the two processes, dogs achieve a far superior smelling ability.

Not to mention, dogs also have a better exhalation process. Air does not go out the same way that it comes in but instead gets pushed out through slits in the sides of the nose. This method helps propel new air in instead of pushing it out, allowing a continual sniff of scent for as long as 40 seconds.

Dogs can detect odors present in the air in parts per trillion.

Dogs can detect odors present in the air in parts per trillion.

What Can a Dog Detect With Its Nose?

Fortunately, although our sense of smell is by far inferior to that of a dog, we are still able to benefit from their innate skills in several unique and fascinating ways. Here is an outline of several areas in which canines use their noses to help humans.


A Labrador Retriever could accurately identify 97% of patients with colon cancer when presented with 185 stool samples from both cancer patients and noncancerous individuals. The dog was similarly successful when given the breath and stool samples of breast, prostate, and stomach cancer sufferers amid cancer-free samples. It didn’t matter if individuals had other conditions or if their cancers were in early or late stages. Dogs have reliably detected ovarian and bladder cancers, as well.


Canines can smell chemical changes and alert humans hours before an impending seizure. Individuals can then take the appropriate measures to either prevent an episode or make sure help is at hand.

Interestingly, dogs do not require training for seizure detection. It is a skill they are born with, and they will naturally whine, bark, or paw to alert of an upcoming attack. Some owners benefit from having their pets learn additional skills such as staying with them when they seize or pressing buttons that connect to emergency services.

Diabetes, Hypoglycemia, and Addison's Disease

Similar to those with seizures, individuals with these three potentially life-threatening diseases benefit from the assistance of medical-alert dogs. These animals are believed to be able to smell dips in blood sugar or pressure and perform attention-seeking behavior to alert their owners. They can also fetch medical supplies and push alarm buttons after they undergo the proper training.

Canines offer superior detection when structures would otherwise have to be torn apart to confirm any mold damage.

Canines offer superior detection when structures would otherwise have to be torn apart to confirm any mold damage.


After a mold dog has been offered samples of harmful microbes to hone its targeting skills, it can search for unwanted growth in buildings. Canines offer superior detection when structures would otherwise have to be torn apart to confirm any damage. They are also highly cost-effective and can scan buildings with hundreds of rooms in hours, minimizing time and money. Dogs have successfully hit on mold hidden in floors, in the adhesive coatings of cupboards, and even on the surface paint layer of walls.


Silas is a black labrador and terrier mix trained in the specialized practice of termite sniffing. Similar to mold dogs, the benefit of termite dogs like Silas lies in their ability to pinpoint unobvious problem areas and identify where the insects initially gained entry.

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Not only can Silas zone in on adult termites, but he also identifies their eggs. And, as if that isn’t enough, he will let owners of termite-infested homes know if they are also harboring bed bugs. Bed bugs produce their own unique aroma and for which dogs show an over 95% accuracy for detection.


In order to be certified as a firearm detecting K-9 team by the Eastern States Working Dog Association, Inc., dogs must be able to sniff out clean or recently fired guns, loaded or empty magazines, brass and shotgun shells, black and smokeless gunpowder, and empty shell casings hidden in buildings, in vehicles, in the open, and in packages.


The Transportation Safety Administration has begun a program using explosive-detecting dogs as a pre-screening tool in hopes of reducing the amount of time travelers spend in security lines. In a few select airports, people are being cleared for expedited flights without removing their shoes, emptying their bags, stepping through scanning devices, or submitting to invasive pat-downs.

Dogs may be superior at detecting explosives to machinery, as it takes a human to interpret what's on a screen, but a dog can recognize dangerous combustibles with a single sniff.


Our military considers an anti-IED program with dogs its most successful strategy for potential explosive detection. Machines, no matter how sophisticated, can malfunction. Further, each gadget generally targets a few specific IED components and requires the use of additional equipment for comprehensive protection. Machines are also bulky, difficult to transport, and costly.

In contrast, healthy dogs display 100% success at detecting several explosive components simultaneously, can move on their own, and cost less than one percent of a piece of IED-detecting equipment.

The U.S. military considers an anti-IED program with dogs its most successful strategy for potential explosive detection.

The U.S. military considers an anti-IED program with dogs its most successful strategy for potential explosive detection.

Pirated DVDs

Dixie, a Springer Spaniel, is just one dog used by UK Trading Standards authorities to zero in on bootleg DVDs. Not only capable of identifying whole, intact DVDs, Dixie can also identify DVD fragments that would otherwise be unnoticeable. She cannot, of course, smell the difference between an illegally copied DVD and a legitimately purchased one. However, she can help identify if DVDs are present and aid in any searches.

Dogs specialize in search-and-rescue and recovery techniques for the living and the deceased.

Dogs specialize in search-and-rescue and recovery techniques for the living and the deceased.

Human Searches and Recovery

Dogs can canvas extensive areas, sampling the air currents as they go in search of general human or a unique individual’s scent. Once they pick up on the targeted smell, they can then trace it back to its source.

Some dogs receive additional training to seek out recently deceased human bodies, fluids, and other decomposing materials. Others specialize in severely decayed bodies and skeletal remains and some even target ancient archaeological graves. Remains can be located both on the ground and underwater.


Remarkably, a plastic container filled with marijuana and immersed in gasoline within a gas tank has proven identifiable by drug-sniffing canines. In 2012, the Oregon State Police (OSP) drug detection program used ten dogs to assist officers in the seizure of 200 pounds of marijuana, 110 pounds of marijuana plants, 1.5 pounds of hashish, 55 pounds of cocaine, 82 pounds of heroin, 49 pounds of methamphetamine, and 3 pounds of psychedelic mushroom.

OSP drug dogs that participated in these operations include yellow labs Hank, Cookie, and Lola; black labs Thunder, Brogan, Quincey, Charger, and Maree; and a brown lab named Hemi.

Cell Phones

Inmates using cell phones to facilitate crime on the streets have a new hurdle to overcome: canine cell-phone sniffing patrols. Sold for around four hundred dollars each, cell phones allow convicts to become a danger to the outside public as well as their fellow inmates. Phones enable them to plan hits, organize escapes, access drugs, and arrange for the delivery of illegal and dangerous items to them in prison.

Hidden away in food, books, shoes, bedding, or elsewhere, cell phones can be challenging to locate without multiple thorough, time-consuming searches. Dogs, on the other hand, quickly follow their noses and hone in on the electronic devices.

Dogs are used to ensure travel safety and to detect explosives.

Dogs are used to ensure travel safety and to detect explosives.


Dogs can detect bees infected with Foulbrood disease, which is responsible for demolishing countless bee colonies throughout the United States in the early ’90s.

Buck, a black Labrador Retriever, is one dog trained to search bee colonies for lethal Foulbrood bacterial spores. Within minutes, he can analyze 20 hives, whereas a human would take three times as long to perform the same search.

Invasive Species

Digger, a rescue dog, was trained in aquatic invasive species detection and works alongside two other canines to sniff out the troublesome Zebra mussel in Minnesota.

In California, boat inspectors use canines to detect a different, though similar nonnative threat: the Quagga mussel. But trouble does not only travel by sea. Hawaii implemented a successful 20-year-long air cargo screening program that targeted brown tree snake stow-aways using dog detection teams.

Ovulating Cows

With proper training, dogs can detect when cows are in estrus, their period of fertility in which they can be successfully bred, with an approximate 80% accuracy. This is crucial for artificially inseminating or impregnating them.

If estrus is not detected, conception rates will be low and fewer calves will be born. In other words, knowing when a cow is in heat is critical. Farmers can either observe cows three times a day for half an hour each time to figure this out or utilize aids, such as dogs, to make the job easier.

Recognizing Dogs' Contributions to Society

Dogs and their noses save countless human lives. They warn of health hazards due to disease, mold, or hidden explosives, and can find people who are injured or lost. They offer us protection from crime by identifying illegal drugs and guns and by monitoring the behavior of inmates in our prisons. They keep invasive species in check on land or sea and in water or air. And, dogs help us sustain ourselves by protecting the well-being of bees—our honey and pollinator source, and maximizing the production of cows—our source of dairy and beef. Dogs, indeed, are man's best buddies!


This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.

© 2013 Schatzie Speaks


Schatzie Speaks (author) on August 18, 2019:

Thank you, Monica! I didn't either until I did the research for this article. I got the idea for writing this after I wrote an article on how cats help people. Then, I felt it was only fair if I created one for dogs as well! Mustn't be biased! ;)

Monica from United States on August 18, 2019:

Wow, this is was an interesting article. I had no idea that dogs could do so much. No wonder they are considered mans best friend.

Peggy James on August 12, 2014:

Love this hub! This is incredible information, some of which I'm learning for the first time. Kudos!

Larry Rankin from Oklahoma on May 14, 2014:

In answer to your question, both our cat and dog seemed to know something was up before we knew we were pregnant.

The applications of dog's sniffing ability is seemingly endless, and it is practical to pursue such channels. They are trying to develop computerized sniffers, but isn't it more financially feasible to just train dogs? Wonderful article.

Schatzie Speaks (author) on September 15, 2013:

Hi Solaras,

Thanks so much for the support and for sharing! I really appreciate it!

Schatzie Speaks (author) on September 15, 2013:

Hi Cidersage,

Thanks for reading and leaving me feedback! I am hoping to write more similarly themed hubs...progress is somewhat slow but I've got a few in the works! Hopefully it won't be too much longer before I can push that 'publish' button. ;)

Barbara Fitzgerald from Georgia on September 15, 2013:

Great post - Thumbs up and shared on FB!

Dan Daugherty from Longmont, CO on September 15, 2013:

Great pics and interesting content. I look forward to more from you along these lines.

Schatzie Speaks (author) on September 15, 2013:

Hi Mel Carriere,

Thank you so much! Haha, I'm sure there must be an identifying "mail" aroma; nothing seems to get past a dog's keen nose! I sincerely hope you encounter far more of the loving mailman sort than the opposite! I know my dog, who has an extreme fondness for the FedEx man and his fun-to-chew cardboard box deliveries, would adore you. :)

Schatzie Speaks (author) on September 15, 2013:

Hi Better Yourself!

I was in the same boat; I had heard of dogs being used as therapy/guide animals and in the military and police forces but the disease detecting was new info! As was the bee and mold sniffing! I already own a dog but am seriously considering making it two or three...can't have too much of a good thing! ;)

Thank you for your comment.

Mel Carriere from Snowbound and down in Northern Colorado on September 14, 2013:

Extremely well written hub. Dogs are amazing animals. As a letter carrier I wonder if we give off a distinctive "mail" odor because dogs that love the mailman tend to love all of them, and vise versa.

Better Yourself from North Carolina on September 14, 2013:

Very interesting! I have always known about the powerful sense of smell dogs have, but am amazed at some of the info above about detecting cancer and illnesses. Really enjoyed reading, thanks for sharing!

Schatzie Speaks (author) on September 13, 2013:

Hi epbooks,

I too love dogs! They are so talented and so smart we can train them to do almost anything if we have a biscuit as a bribe! :D Needless to say, my dog is a little on the plump side.

Thanks for reading!

Schatzie Speaks (author) on September 13, 2013:

Hi lifelovemystery,

They only discovered the whole inhale/exhale thing in detail recently, but it definitely helps explain why we could never come close to smelling what a dog can! They are trying to model smell detecting machinery after dog noses but without the large canine brain that comes with them I can't see any invention coming close to the real deal anytime soon!

Thanks for stopping by and commenting! :)

Elizabeth Parker from Las Vegas, NV on September 12, 2013:

I love dogs and they never cease to amaze me. Well written and informative hub. Thanks for sharing!

Michelle Orelup from Las Vegas, NV on September 08, 2013:

This is Fascinating! I had no idea that dogs were able to detect so many different things with their noses. I also didn't know that they don't inhale and exhale from their nostrils. Great information. Voted up!

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