The dog’s nose, together with the olfactory system, represents an early warning system useful for identifying the presence of food and any dangers: consequently, it plays a very important role in the survival of the animal.
The dog’s nose is a powerful tool that guides them into a world very different from the one we are able to perceive. Undoubtedly, it is difficult for us humans (who tend to relate everything to ourselves) to be able to accurately understand the enormous power of canine smell.
What is behind this amazing ability? In an attempt to answer this question, scientists have set themselves the goal of elucidating the physiology of canine smell. In this article we will tell you about some of the most relevant discoveries.
6 curiosities about the dog’s nose
1. It is a multifunctional organ
The air that reaches the dog’s nose is distributed in such a way as to allow the performance of two functions. One part is intended for smell, while the other for breathing: a dog’s nose, in fact, has the ability to separate the air.
One part directly reaches an olfactory detection chamber which distinguishes odors, while the other crosses the trachea and is reserved for breathing. Olfactory sensing occurs when air forms eddies that circulate through a system of turbinates, where the olfactory receptors are located. In dogs, the turbinate system is much more complex than that found in humans.
The canine turbinate system involves an area dedicated to the sense of smell measuring approximately 100 square centimeters, an area far exceeding the five square centimeters believed to be present in humans.
Thus, the olfactory function and acumen of dogs may depend on the flow and permanence of the odor molecules in the so-called ethmoid recess. Here, the smell receptors are exposed to prolonged contact with the olfactory molecules of the inspired air.
2. The dog’s nose has a second odor detection system
Between their nose and mouth, dogs have a special organ with which they identify smells. This organ is still present in humans, but it is only a non-functional vestige.
It is known as the vomeronasal organ or Jacobson’s organ and is considered an auxiliary organ of the sense of smell. Through this organ, the dog identifies non-volatile chemical signals, which require direct physical contact with the source of the smell, such as pheromnes.
It is interesting to know that, unlike the main olfactory pathway, which sends neuronal signals to the olfactory cortex, the vomeronasal organ sends neuronal signals to the accessory olfactory bulb, then to the amygdala and, ultimately, to the hypothalamus.
3. And why so many receptors? They are used to smell you better
The repertoire of olfactory receptors in mammals includes hundreds of different types of receptors. These specialized proteins are very different and manifest in different sub-compartments of the nose.
The dog’s nose is believed to have significantly more olfactory receptors than in humans. However, it should be noted that there are no reliable quantifications that indicate what the limit of the canine olfactory capacity is.
What we do know is that, in humans, the number of functional olfactory genes is around 450, compared to more than 800 known in dogs. A study of just two dogs estimated that the canine sense of smell exceeds ours by four to five orders of magnitude. This means it would be 10,000 to 100,000 times sharper.
However, recently other groups of scientists have tried to establish that there is no relationship between the number of olfactory genes of a species and the sensitivity of smell.
According to some experts, comparing a dog’s olfactory capacity to the sense of taste (by way of example only), while a human might notice the presence of a teaspoon of sugar in coffee, a dog could perceive a teaspoon of sugar in a million gallons. (corresponding to 3,785,411 liters) of water, which is equivalent to the volume of two Olympic swimming pools.
4. The olfactory bulb is the “thinking” counterpart of the dog’s nose
The odorous substances attach to these olfactory receptors and generate a signal that is transmitted to the brain. The brain area that decodes the signal triggered in the nose by the odorous substances is the olfactory bulb. Also in this case we can detect a difference between different species.
We know that the volume of the olfactory bulb in dogs and humans constitutes, respectively, 0.31% and 0.01%, in relation to the volume of the brain.
5. The humidity of the dog’s nose is a fundamental aspect
A dog’s nose secretes a thin layer of mucus, which keeps it constantly moist. This mucus is useful for the purpose of effectively absorbing and capturing odorous molecules.
Dogs continually lick their noses to taste aromas through their mouths. There is no reason to be surprised, therefore, that they smell anything before eating it.
6. Dogs smell in 3D
Dogs can smell using each individual nostril independently. We know that a dog’s brain uses the different characteristics of smell through each nasal cavity, from which it is able to accurately determine the origin of the aroma.
This phenomenon manifests itself in a manner analogous to our vision. Each eye forms its own (slightly different) image of the world, which the brain processes to produce the three-dimensional image we perceive.
In summary, the dog’s nose is crucial for its survival and reproduction. The ability to recognize a variety of odorous substances associated with food, predators and mating partners is essential for its species.
As a result, their sense of smell possesses the ability to identify and distinguish an almost unlimited number of chemical compounds. This result is achieved thanks to an elaborate olfactory system composed of different chemosensory subsystems.