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Unbelievable Things Dogs Can Smell

Anuj Mudaliar Nov 23, 2018
The fact that dogs have a very good sense of smell is common knowledge. However, few realize how sharp this ability really is. Here, we discuss some really unbelievable things that dogs can detect by using their noses, thereby helping humans in a number of fields.

Did You Know?

The nose of every dog is made in a pattern of ridges and dimples, which along with the outline of the nostrils, is unique like human fingerprints. Reputed breeders register the nose print of their dogs, which helps in case the animal gets lost or stolen.
An examination of the working of a dog's brain will reveal that, it specializes in identifying a vast variety of scents. Dogs are known to rely largely on their sense of smell, similar to how most humans rely on the sense of sight.
The area of the brain associated with processing smells is more than 40 times bigger than that of a human. Also, dogs can have between 125 to 300 million olfactory receptors in their noses, depending on the breed. This means that, a dog's sense of smell can be 10,000 to 100,000 times stronger, enabling them to sense some truly surprising things.
Given their spectacular abilities, humans have made use of dogs for detection purposes since time immemorial. While their use as drug sniffer dogs are well documented, there are many other lesser-known fields where dogs have used their sniffing abilities to good effect. Let's see what all things dogs can smell through.


Hormones in the human body are always changing in response to our physical and emotional states. Dogs are very adept at identifying these changes through their acute sense of smell, and they know if a person is afraid, sad, or ill.
To make the best use of these skills, therapy dogs are now trained to appropriately accompany people with severe cases of depression or anxiety, and help take the load off their minds, which makes their help in psychiatry a great boon.


With the eruption of travel, either through bus, train, or airplane, the number of bedbug infestations has increased by a huge margin in the last decade. The worst part about this is that, bedbugs are extremely sneaky in nature. They bite people painfully, suck their blood, and escape with almost ninja-like stealth back into their hiding places.
In response to this menace, pest exterminators have started offering services, where dogs are used to sweep homes for these pesky pests.
Dogs can smell through things such as furniture, fake walls, etc., and alert the handler to potential hiding spots of the bugs. Although this service is quite expensive, studies have shown that dogs which are trained for this purpose have an extremely high accuracy rate (up to 96%).

Drowned Corpses

In the United States, police forces often use dogs to find things that are underwater, such as drowned corpses, or pollutants which are harming the environment. They are trained to recognize a wide range of scents.
So, the scent emitted from a dead body floats with the water currents of the river or lake before being released into the air. Dogs can track the scent either by being on a boat, by swimming, or even from the shore, eventually leading the searchers to the pollutant or body.


Since the 1960s, beekeepers around the globe have been fighting a battle against the 'American Foulbrood' disease, which has impacted several colonies, even threatening extinction for some bee species. However, since 1970s, dogs have been aiding the apiaries by detecting diseased beehives, which are discarded, before the infection has a chance to spread.
Dogs do this by recognizing the scent of the disease-causing bacteria. They can easily inspect over 100 hives for infection, within an hour. However, the same work, when done by a human, could take up to two days, making these trained dogs really invaluable. Similarly, dogs can also be trained to detect bacteria and fungi which cause diseases in plants.

Whale Feces

Whales are very elusive creatures, and biologists study every scrap of information available to them to get a better understanding of these marine behemoths. Their feces are also important in order to understand their diet and health, which is why, researchers are often out in boats hunting for these giant turds.
There is only one problem. The feces floats on water for approximately half and hour before sinking to the seabed, which means that they have to be found quickly. To counter this problem, dogs are now trained to detect floating poop.
With their exceptional sense of smell, they can trace whale feces from over a mile away. They usually guide the boat captain towards the whale waste by leaning left or right, or by twitching their ears.


Most of us have heard about truffles at some time or the other. They are wild fungi which grow deep beneath the ground, and due to the difficulty in growing them in farms, they are very rare, and can cost hundreds of dollars. While it is very difficult for humans to detect the fungi, dogs can detect the scent quite easily.
Therefore, these animals are trained to run around the countryside and dig up the truffles when they detect the scent. Although pigs can also detect truffles, they are more likely to eat the fungi, which is why dogs are more preferred. However, trained dogs are very expensive to purchase, running into several thousands of dollars.


Dogs are capable of smelling changes in human hormones and sugar levels. Therefore, in the past decade, several dogs have been trained across the world to detect conditions such as epilepsy, diabetes, and cancer.
They can detect the unique smell of tumors, low blood-sugar levels, and hormones that occur 10 - 15 minutes before an attack of epilepsy. With training, they can alert the human to the approaching predicament, thereby giving the person a good chance of taking precautionary measures.
Researchers believe that, well-trained dogs have a better accuracy rate than regular medical machines which are used to detect the ailments.

DVDs and Computer Hardware

While the role of drug dogs for smelling things like cocaine, heroin, etc., is well known, recently, police dogs have also been trained to identify a material known as polycarbonate. This material is used in most computer related items, such as CDs, DVDs, and hard drives.
So, dogs have been instrumental in wreaking havoc on illegal pornography, DVD counterfeiting, and other cyber-crime trades occurring largely across Southeast Asia. Such has been the success of these canine units, that DVD pirates in Malaysia offered a USD 30,000 reward for the death of the dogs.

Ovulation in Cattle

With the immense demand on dairy and meat products, cows are most often impregnated with the use of artificial insemination. However, this process has a risk: farmers may inseminate the cows with bull semen at a time when the cow is not ready. Doing so can prove very costly, as bull semen is very expensive to purchase.
A few such mistakes can even push a farmer into bankruptcy. To avoid such errors, farmers are training dogs to detect when the cows are in heat. Dogs smell urine samples of the cows and identify chemical signatures, which indicate whether the cow is ready for pregnancy or not. Well-trained dogs have nearly 100% accuracy rate in this task.

Minerals and Ores

In Finland, the government sponsors programs which train dogs in finding mineral deposits. With several valuable sulfide rocks available across the nation, the finds made by the dogs can have a good impact on the country's economy.
Dogs can easily track the rotten egg-like smell of sulfide which comes out into the air whenever such rocks break. Because they have an accuracy rate of more than 94%, in more recent times, many other countries have adopted this program for themselves.

Ambush Equipment

Dogs have been part of the American army since the Revolutionary War. Usually, they helped in alerting the troops to intruders, or to smell out enemy soldiers in unfamiliar terrain.
While these facts are well known, few know that, during the Vietnam War, dogs were not only used to detect humans, but they were also able to smell out weapons, tunnels, booby traps, landmines, and other forms of ambush, saving the lives of several US soldiers.
They were trained to alert their handlers to traps without resorting to barking, in order to avoid detection by the enemy. Dogs used other signals such as raising the hair on their neck, crossing their ears, or even walking on their hind legs, if they located anything dangerous.
With our increase in knowledge about the potential of dogs in detecting disease, crime, etc., just through their noses, the applications are seemingly endless. People can benefit tremendously from these animals, and live a better life, proving once again that dogs truly are man's best friend.