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About sniffing, smelling and a dog's nose

Generally, most of us realize that a dog has a better sense of smell than humans. Because he senses broken bones and pulls us to them through half the estate. Because he can sniff the cat before we even realize that the dog has already sniffed something. Because he feels a tiny delicacy hidden deep in our pocket. In addition to sniffing sex, the dog can also sniff the readiness to brew, what illness the dog has recently undergone, or what was the last meal he ate. Increasing the age is also not a problem for him, because aging is a metabolic and therefore chemical process. And as you know chemistry means fragrances. The dog senses that another dog was bathing, that he just urinated or that he has a need to do so. He senses his identity, condition and probably even his emotions — whether he is scared, worried or happy. And probably everyone has also heard about hunting dogs missing or poachers, dogs looking for mines and forbidden substances or detection dogs, looking for urine samples of people with cancer.

He senses his identity, condition and probably even his emotions

Dog nose — Photo by Marek Szturc on Unsplash

Hunting dogs can detect much more than just a disease. After dogs were trained to look for drugs and explosives, the possibilities soon became endless. People started training dogs looking for smuggled agricultural products, venomous snakes and plant pests. Dogs are trained to look for microscopic amounts of environmental pollutants, toxic products used in industry or ending up in landfills, or even derived fuels. They sniff sea cucumbers illegally removed from the Galapagos Islands and smuggled fangs and horns of elephants and rhinos. And dogs search for us, people: rescue and tracking dogs follow the trail of the missing, find dead or escaping criminals, as well as people who lost their orientation and are lost.

The American legal system confers power on dogs: no one else but the US Supreme Court has qualified dog smell as a tool unlike any other.

A man gives out a strong enough smell that a dog can find even after a long time, underwater, when the person has already moved away, and even when the object with which he was in contact has been torn apart by the explosion. In one study, it was found that trained bloodhounds are able to recognize who was touching the homemade bomb, just after its explosion. The smell left on the load casing when setting the mechanism is “even”, even if there is not much left of the bomb itself. Dogs are trained to find people who have drowned: the odour of decomposition leaks onto the surface of a lake or other stagnant water tank. Some dogs even manage in the river. Where sonar, divers and underwater cameras fail, the dog can start from the shore, and then by boat, narrow the search space to an area of ​​six meters in diameter. Avalanche dogs are able to find missing ones under a seven and a half meter layer of snow. The smell of man comes to the surface and the dog, digging a little to make sure, signals the right place.

Dog’s ability to recognize early that you’re approaching home

Perhaps you think your dog has some psychic abilities? Many people think so. Because how is it possible that much earlier before you get in the door, your dog already knew that you are coming home?

The truth is, in reality, however, we announce our arrival from afar as effectively as if we were wearing a cowbell around our neck or emitting a smell as strong as skunks. We appear to the dog before we actually come and stay in place long after we left. So yes … dogs have some special skill. A special ability to sense smells.

A few years ago a certain experiment was carried out to check to what extent the prediction of owner return is dependent on smell. It has been suggested that in addition to obviously sensing a person and hearing him through the door, there is a powerful combination of two factors. One of them is the unique smell of the owner for his dog. The second one is the ease with which dogs learn our habits: we leave the house and come back at similar hours. But the question arises: how can your dog know that it is just the time of your return, since: first — he does not know his watch, and secondly — every day the sun sets at a slightly different time? It was found that the smell we leave behind at home every day fades at a certain rate. As our absence continues, the house smells less and less.

Accordingly, a test was carried out involving the introduction of the “fresh” smell of the owner into the house. The goal was to see if he would make a dog who thinks his master just left the house will be surprised when he appears in the door.

The test has been confirmed. In cooperation with the marriage, the authors of a certain scientific program a few hours after leaving the owner put at home his sweaty undershirt, spreading such a strong smell as if a man left quite recently.

Unsurprisingly, the dog, contrary to its custom, did not wait outside the door when its guardian returned at the normal time. He slept on the couch because since the strong smell of the guardian still hung in the air, he could not expect it until a few hours …

Sniffing Golden Retriever puppy - Photo by Will Malott on Unsplash

Dog’s noses are fascinating: as diverse and as full of individual details as human fingerprints. But what’s with that nose that it’s so good?

Dogs use scents to communicate. In dogs, like many other mammals, the olfactory system does not end in the nose. Dogs have a kind of “second nose” below the bone separating the nostrils and above the palate. It is the so-called Vomeronasal organ (what scientists shorten to VNO) or Jacobson’s organ, which serves the sense of breath no less than the nose. Thanks to the VNO organ, dogs are able to identify pheromones, which are very fine chemical fragrance molecules that the usual smell mechanism does not recognize. The VNO is hidden behind the nose, so it does not reach the air sucked in when it is inserted. Fragrances must dissolve in saliva and are sucked in with it. The pumping mechanism is either activated by direct contact with the odour molecule or requires the animal to make an awfully silly grimace known as flehmen. VNO can detect pheromones due to the fact that they are mainly water-soluble substances, not very volatile molecules with low atomic mass. Similar features have many other molecules, i.e. hormones, which can carry information about the identity of the animal or group to which it belongs. VNO receptors are particularly sensitive and highly specialized, in contrast to olfactory nasal receptors that respond to a wider range of substances. So dogs sniffing their mouths and backs alternately are nothing more than chemical communication of their sex, readiness to brew, information on health — and about their identity in general. Saliva and urine can carry the same information for any animal.

Sniffing dog - Photo by Andrey Konstantinov on Unsplash


If you’ve ever seen a horse wrap a highlander’s lip, frowning as if he had just eaten a lemon and lightly popping its mouth, then you’re witnessing a classic flehmen. The whole grimace is to draw the scent into the share nose organ. Similarly, the pig opens its mouth wide; the cat has a half-open muzzle (which makes him look concerned). Also, the dual tongue of the snake moves to capture the smells, then delivers them symmetrically to both parts of the VNO.

The vast majority of dogs, in classic flehmen, do not turn their lips like a horse. Sometimes, after an inhalation sequence, the dog may wrinkle his nose with a clearly visible grimace and bare his teeth. Licking is even more effective. The extraordinarily long canine tongue is great not only for licking leftovers from a butter container, but is also great for delivering fragrance particles to the VNO for them to be examined there.

The dog’s nose is constantly moisturized thanks to the mucous glands, which allows the fragrance particles to stick and move them inside the nose, and there are special hairy structures that transport the fragrance further. Eventually, the fragrance particles land on a special, porous bone structure and remain there regardless of the breathing process. When the dog sniffs, the smell is transferred from the structure to the olfactory receptors, but when the dog breathes the air passes below the bone structure on which the smell “hangs” and goes to the lungs.

And such a quick and loud roar when exhaling, which you probably hear, allows the dog to clean his nose of the previously collected smell and download a new one for analysis.

In addition, the dog’s nose contains receptors that react to temperature changes, which allow you to turn to a cool breeze that can carry new smells.

The dog also has Maser’s organ (responsible for quick evaluation of smells, e.g. when collecting food) and Gruenberg’s scroll at the end of the nose (responsible for the reception of pheromones, heralding danger).

A significant part of the dog’s brain is responsible for analyzing smells!

The front of the nasal cavity has two nostril holes that lead to the right nose, two to fifteen centimetres away. Interestingly, the dog can use each nostril separately and in different ways. When he feels something new and pleasant or at least indifferent, he begins to sniff first with his right nostril and then switches to the left. `

“By filming dogs that sniffed cotton balls saturated with different fragrances, the researchers found that the smells of lemon, food and secretions of the female trigger the” right to left “scheme. However, when the dog was in contact with the smell of adrenaline or sweat of the veterinarian employed in the kennel, he was sniffing his right nostril. It is believed that the choice of the nostril is associated with the cerebral hemisphere involved in a given activity. The right nostril connects to the right hemisphere (i.e., located on the same side — unlike other sense organs that connect to opposite hemispheres)., Which is more often associated with anxiety or aggressive behaviour than the left, analyzing familiar stimuli. If the dog sniffs you only with his right nostril, then you are distrustful.“ — Alexandra Horowitz “Being a Dog: Following the Dog Into a World of Smell”

Why is this so important?

First of all, we must remember that we get to know the world mainly through the sense of sight. In contrast, the dogs learn everything about the environment through the sense of smell: they know who was in the staircase in the morning and how long ago, which neighbour stopped longer at the letterbox and whether the dog from the next neighbourhood is healthy, sick, old or young. This is their way of watching the world, so if our dog sniffs heavily, let him, because he watches the world his own way, as we look around and gather information using the sight.

This is their way of watching the world

Have you ever seen your dog revolve around a toy abandoned on the grass and can’t seem to find it even though it has it in front of you? His smell is all right, he simply explores the surrounding environment, just as we observe an area by our eyes. He usually moves with his nose towards the toy, stops for a moment over it, exhales briefly and goes on. For the bipedal creature standing next to it, that is, its owner, for whom eyesight is the most important, it looks as if it had fooled it in the stupidest way. This is not true. His dog will return to his toy. First, it simply assesses the concentration of all the smells in the environment to find the strongest — just like you, you look through all the delicacies at a party, before you focus your attention on the chocolate fountain. Along the way, the dog performs a series of quick “short breaths, five to twelve per second. Such sniffing takes place at a rate comparable to canine panting — an average of 5.3 tongue movements per second — so it’s probably just as energy efficient.

Secondly, sniffing is also one of the calming signals sent by dogs to other individuals of their species as well as to us humans. Were you in a situation where the dog ran away from you and you called him? And nothing. You are calling more upset. Thread. You cry furiously and your pet suddenly starts to smell the grass and doesn’t want to approach you at all or does it with a huge bow. And this sniffing is a signal for us: “calm down, I hear you are nervous and I do not feel comfortable.” If our dog, seeing someone coming from the other way, starts to step aside and smell it, let him do it — he communicates to the world that he is not looking for problems and sends one of the calming signals that is to enable him and the other person to pass by comfortable conditions, no confrontation.

And the last function of sniffing, very practical for us: it silences the dog, relaxes and tires him. Sniffing and pulse rate showed a correlation, too. When dogs are sniffing, their pulse rate is going down. The more intensely they are engaged in the sniffing behaviour, the more their pulse rates are lowering.

Hence the popularity of activities related to this skill: nosework (odour detection), tracking or ordinary olfactory games.

The olfactory play has many advantages:

  • we have a tired, satisfied dog who can discover new smells and take on new challenges every day, which significantly improves his quality of life satisfaction;

  • successfully searching for hidden rewards (delicacies, toys, people) build confidence in fearful dogs;

  • mental fatigue after olfactory work works very well in behavioural therapy of hyperactive dogs;

  • providing olfactory play in our cooperation builds a relationship with the dog and affects the quality of the dog-guide relationship;

  • waiting for us to prepare the toy and issue the “search” command teaches impatient dogs how to control their emotions.

What olfactory games? 

How many dogs and how many owners, so many ideas for sniffing! The most popular are olfactory mats, i.e. rugs with long fleece fringes, in which the dog needs to look for treats or food, and which are very often used by behaviourists in the treatment of anxiety dogs and to provide the dog with the right amount of mental work. In addition, all kinds of hiding delicacies at home, in various rooms, e.g. before leaving for work, burying toys in the sand, limping delicacies in the bark of trees, and spreading delicacies in the grass works well. These are just a few ideas :)

Very good are also the toys from which the dog must get treats (kong, dough balls, but also the economic versions from a rolled towel, rolls of toilet paper or crumpled paper balls). Such toys, based on the sense of smell, require the dog to work out how it can extract fragrant treats and thereby stimulate his brain to work.

The more fun with the nose, the better! We can use the whole daily portion of food for treasure hunting by our dog. Let’s remember not to demand too much from our pet at first and tell him a little bit, and with time he will become a seasoned seeker 

Finally, a small curiosity:

Did you know that in addition to building the mouth, some other physical characteristics and behaviour of dogs are also subordinated to the sense of smell? For example, bloodhounds are endowed with such large ears (sometimes exceeding 33 centimetres) for a reason. They contribute to the super sniffing abilities of this breed. When the dog sniffs with a low nose, its ears sweep the ground, lifting fragrance particles out of it. They are like two fans mounted near the mouth blowing the smells straight into the dog’s nose. Even saliva dripping from the mouth of a dog helps deliver fragrances to the share nose organ where they are further analyzed.

You can talk about a dog’s nose for hours!

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