How Well Can Dogs Smell? 5 Weird Things Dogs Can Sniff Out

Dogs are known for sniffing out items like narcotics and explosives. Did you know that scent discrimination training can extend to stranger things?

Melvin Peña  |  Mar 5th 2015


In December 2007, I took my dog, Tina, hiking in the woods. When we got home, I was dismayed to find that my camera had fallen out of my pocket. Because we’d strayed from the trails that day to explore, I gave up the camera for lost.

The very next day, I decided to stick to the trails, but Tina started pulling me into the forest. After a few minutes, she stopped, and sniffed the ground. I looked down and there was my lost camera! I was awestruck.

Frequently, our dogs will sniff at us and then give us a good lick. This is one way in which we see a dog’s piercing senses of scent and taste working in tandem. Rather than the camera itself, it is much more likely that Tina recognized some trace of a scent or taste she associated with me among the leaves, leading her to the lost camera. Even without scent discrimination training, our dogs’ noses are absolutely remarkable organs.

Why do dogs smell everything?

Along with her tongue and ears, a dog’s nose is her most consistent and powerful tool for experiencing the world. Because dogs rely so heavily on their noses, their brains have adapted accordingly. The length of a dog’s muzzle makes a significant difference to the precision with which they can smell. Thus, a Beagle or a Basset Hound is a superhero of scent compared to, say, a Pug or a Pekingese, but any given dog’s brain has scent-processing equipment on a scale that dwarfs that of their human owners.

Dogs and scent discrimination training

There are few limits to what dogs can find with their noses. Whether it’s called “nose work,” “tracking,” or “scent discrimination,” there are as many approaches as names for teaching a dog to sniff out a particular item. If something has a scent, a dog can be trained to alert us to its presence, or, indeed, its absence. Even more astounding, it needn’t even be a physical item, only to have a particular odor or olfactory emanation associated with it.

All over the world, working dogs are being trained to use their noses to locate unusual items for science, manufacture, farming, and even human health. No matter what you’re looking for, chances are, a dog’s nose can find it. Through practice, a key word, or repeated exposure; with or without a direct command, here are just a few of the ways that dogs are helping people simply by following their noses.

1) Environmental changes

Dogs have been trained to detect any number of environmental factors. Dogs not only eat poop, for instance, but can seek out fecal matter and other human waste products found in raw sewage. They do this to trace the routes that sewage travels, and to discover potential leaks and hazards to drinking water reservoirs. This skill helps to preserve the quality of watershed areas and the purity of the water we use every day.

Dogs also help track changes in creatures that humans interact with, both wild and domesticated. Beekeepers utilize dogs to detect bacterial diseases that can negatively affect an entire hive of bees. Wildlife conservationists and scientists who study migratory patterns in a variety of animals — from birds to whales — have used dogs to locate the dung of these animals and collect it in order to research their dietary habits.

2) Invasive insect species

Certain insect species can wreak havoc on property and agriculture. In housing and real estate, dogs have been employed to sniff out termites living in the walls of buildings. They are also used to locate bedbugs returning to infest homes, hotels, and other living spaces from around the world. In the realm of farming, a well-trained dog can prevent crop loss by detecting both invasive insect species that are known to infest and eat growing crops, as well as diseases that can kill plants.

3) Illicit technology

In their capacity as police dogs, canine sniffers around the world have assisted law enforcement officials to find contraband in prisons and black market technology elsewhere. Because there are unique metals and chemicals in cellular devices, dogs have rooted out phones hidden in prisons and jail cells. Similar compounds used in DVD and Blu-ray manufacture have prepared dogs to find pirated movies.

4) Rare and precious food items

Truffles are a sort of rare and precious delicacy. Found growing near tree roots in Europe, the Americas, Africa, and Asia, truffles are used in any number of recipes, as well as prepared and eaten on their own. While pigs are most famous as truffle hunters, they have also been known to eat them upon discovery. Dogs trained to find truffles are more likely to take pride in finding these fungi than to devour them.

5) Human health issues

Dogs’ noses are sensitive enough to detect hormonal and chemical changes, not only in their owners, but in complete strangers as well. Ranchers utilize dogs to know when their cattle are in heat, so yes, dogs can also smell when humans become pregnant. Your dog may not understand what exactly is going on, but can detect the scent of new hormone production associated with pregnancy.

Likewise, dogs have been proven to recognize a wide range of scents linked with human diseases. Dogs are trained to sense when diabetics are most in need of an insulin injection. They can also smell chemical byproducts in sweat, breath, urine, and feces to detect skin, lung, bladder, ovarian, and colorectal cancers.

What odd things have your dogs sniffed out?

Humans have been exploiting their dogs’ extraordinary sense of smell since time out of mind. Over the last 150 years or so, however, scent discrimination training has become increasingly exacting and dedicated. We’ve all heard of and seen, at airports, checkpoints, and other sites, police dogs whose job it is to locate fugitives, missing people, explosive devices, and a wide variety of narcotics. What is the strangest thing your dog has ever found?

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About the author: Melvin Peña trained as a scholar and teacher of 18th-century British literature before turning his research and writing skills to puppies and kittens. He enjoys making art, hiking, and concert-going, as well as dazzling crowds with operatic karaoke performances. He has a one-year-old female Bluetick Coonhound mix named Idris, and his online life is conveniently encapsulated here.