The Sense of Smell in Dogs
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In the early 20th century, the German ethologist, Jakob Johann von Uexküll, coined the term 'umwelt' to refer to the different ways in which animal species perceive their environment depending on their sensory abilities. Uexküll theorised that organisms can have different umwelten, even if they share the same environment. When analyzing their surroundings, dogs heavily rely on their sense of smell.
In this AnimalWised article we will explain how the dog's sense of smell works and how you can stimulate this sense in your dog.
How does a dog's sense of smell works?
When dogs inhale, they divide the air into two streams through their nasal turbinates. The turbinates are long, narrow, sinuous boards of bone that protrude into the airway of the nose. One stream enters the lungs to allow breathing. The other reaches the olfactory membrane, where odor molecules are captured and processed by special cells.
Unlike humans, dogs have an additional olfactory organ that enhances their ability to smell. The Jacobsen's organ, also known as the vomeronasal organ (VNO), is a specialized part of the dog's olfactory apparatus. It is located in the soft tissue of the nasal septum in the nasal cavity, just above the roof of the mouth (the hard palate).
This organ serves as a secondary olfactory system specifically designed for chemical communication. This is because this organ detects pheromones (body odors), perhaps giving the dog its tremendous ability to identify and recognize animals and people.
The nerves of the Jacobsen organ lead directly to the brain and differ from the other nerves in the nose in that they do not respond to common odors. Rather, these nerve cells respond to a range of substances that often have no odor at all. In other words, they work to detect "imperceptible" odors.
To maximize their olfactory capacity, dogs increase the speed of their breathing by inhaling and exhaling very rapidly, a movement known as "sniffing." Additionally, dogs have a good scent memory, which enables them to recognize other dogs, even if they haven't seen them for years.
You might be interested in this other article, where we explain why dogs smell each other's butts.
In comparison to humans, how good is a dog's sense of smell?
The sense of smell of dogs is extraordinary and far superior to that of humans.
First, the epithelium or olfactory mucosa of the dog covers an anatomical area of 150 to 200 square centimeters, while that of man is only between two and 10 square centimeters. Given this fact, it is obvious that dogs have many more olfactory receptors than we do, about 250 million compared to humans' five million.
If we compare the size of the area of the brain responsible for processing odors, humans are also at a disadvantage. Since our olfactory bulb does not have to process as much information as a dog's, it takes up much less space in our brain. In fact, the part of a dog's brain responsible for analyzing smells is about 40 times larger than the comparable part of the human brain. It is even estimated that dogs can smell 1,000 to 10,000 times better than humans.
We humans have trained dogs to help us with a variety of tasks that require detecting odors that are imperceptible to us. For example, there are dogs that specialize in detecting human bodies in water, under the snow, or under rubble. Others are able to detect drugs or explosive substances in large areas and from great distances. Finally, there are dogs that are able to smell chemical changes in our bodies to warn us in advance of hypoglycemia, epileptic seizures, and other illnesses.
You may be interested in this other article, where we explain how dogs are trained to find drugs.
Interesting facts about the sense of smell of dogs
Now that you know how many olfactory receptors dogs have and how their sense of smell works, let us look at some more interesting facts:
- Dogs are not able to "get used" to smells: When we notice an odor in the environment, we gradually become accustomed to it and after a while we are no longer able to detect it. This process is called "odor habituation." This phenomenon does not occur in dogs, because since the sense of smell is their most important perception channel, they never stop perceiving the odors that surround them, even if they have been exposed to them for a long time.
- Dogs can use their sense of smell to establish temporal sequences: This is because they are able to detect the concentration of odor molecules in the environment. The higher the concentration of molecules, the more intense an odor is, and the less time has passed since the source of the odor was present. Thanks to this ability, dogs can easily follow tracks of humans or other animals.
- Not all dogs have the same olfactory ability: Breed, skull morphology and genetics, among other aspects, influence the development of the sense of smell in dogs. Currently, the dog with the best sense of smell is the bloodhound, also known as the Saint-Hubert dog, a dog of Belgian origin that has more than 300 million olfactory receptors. This sense is less developed in brachycephalic dogs (flat muzzle) or dolichocephalic dogs (very long muzzles) because their anatomy makes it more difficult for odor molecules to pass through than in mesocephalic dogs (proportional muzzle).
- Each of the dog's nostrils functions separately: Unlike our nose, the canine nose has two holes or nostrils that can independently sense odors to locate their origin and send different signals to the brain. This is often colloquially referred to as "sniffing in stereo or 3D sniffing".
- The dog's nasal pattern is unique to each animal: The lines and patterns that make up the skin tissue of the dog's nose are unique to each individual, just like our fingerprints. This discovery has led to several countries already using dog nose prints as proof of identification in cases of loss, theft, or abandonment.
You may be interested in this other article, where we explain what 10 smells dogs hate.
How to stimulate a dog's sense of smell?
Depending on your dog's preferences, you can offer them an infinite number of options to train their sense of smell alone or accompanied. Something as simple as hiding food, toys, or even hiding ourselves around the house, can be very stimulating and fun for your dog. Learn some tips on how to train your dog's sense of smell:
- Make the most of daily walks: You do not have to spend a lot of time thinking about how to stimulate your dog's sense of smell every day. It is sufficient to offer them enriching walks and let them explore everything they want. Ideally, you should let your dog sniff around large, green, and quiet locations like a field or park while wearing a long leash. Also, let your dog spend several minutes smelling the same spot, since there should be very interesting information there. If your dog does not normally sniff when you walk them, you can encourage them to do so by scattering pieces of food around a certain area and encouraging them to look for it, helping them as you see fit.
- Use puzzles and interactive toys: The sense of smell can also be stimulated without leaving the house. There are hundreds of toys and puzzles on the market in which food can be hidden for the dog to find and retrieve. These products have a double advantage, because they not only invite the dog to sniff more, but also provide a mental challenge that promotes decision-making and other cognitive functions. Of course, we must adapt the difficulty level of these games to the abilities and experience level of our dog because if not, it can also be a frustrating experience.
- Play hide and seek with your dog: Stimulating your dog's sense of smell does not always require physical materials or toys. You can also do this by playing a game of hide and seek inside or outside the house. While one person holds and distracts the dog, run into a room or behind a piece of furniture and hide. Along the way, you can touch various objects to leave a trail that the dog will follow. Once hidden, say their name or whistle once to get your dog to come to you.
If you want to know more games you can play with your dog to stimulate their sense of smell, do not miss the following article on games you can play with your dog at home.
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