Surely you have heard it a thousand times: the vision of a dog is much more limited than, for example, that of a human, since it does not distinguish the colors. In fact, they say that come with your sense of smell, which, in comparison, is hiperdesarrollado. And it is that indeed, the snout of a dog works through a mechanism infinitely more complex than ours.
As soon as there is a gust of wind, its fluffy truffle helps capture each aroma that brings with it the breeze, to then record them "in stereo". I.e.: each nostril captures odors separately, allowing you to distinguish not only what source they come from, but where each one of them is.
For accuracy, as soon as the air enters through the nose of the dog, he meets two compartments: one for breathing, and the other to smell. So it passes their smell receptor cells, which are incredibly numerous in relation to the human. Up to 300 million are located in their snouts in comparison to the 5 million that we have.
We already say that their sense of smell is much more developed than ours, and in fact there is evidence that bring to light the virtues of a body that works like a Swiss watch. While the man inspires and expires by making use of the same hole, his pals quadruped collects air by the front trenches, but it drives out on the sides of these cracks, generating air movements which facilitate the introduction of new molecules of smell. Molecules whose information is processed by a much more developed than the human brain by having a "bulb of smell" more big. They distinguish and remember a great variety of odors.
Hey, if we are able to smell a perfume and recognize who take it to have it forward in a small room, the dog would be able to assimilate to each of the ingredients of the same... being in the middle of a football field. Everything has a distinguishable oloroso profile for the dog: each animal, or even insect that is in a street tree. And you can know both where and in which direction it is moving.
The dog's nose can detect things that are not even visible: thanks to its organ vomeronasal, located on the upper palate of the mouth, detect hormones that all animals (including humans) release naturally. That alert them of threats, says if this or that are potential friends or foes, warns States of mind, and even allows you to detect diseases and deduce if pregnant woman who has front. Do you ever wondered why it helps you when you're sad or they are angry when they see you angry? Because such States of mind derived hormones.
There is more. As if not enough advantage that lead us in the field, their sense of smell travels in time! The past manifests leaving footprints odorous aftermath of someone, either impregnating aromas of the sites that has been in your body. And the future is in the breeze conveying with it smells of who is approaching. So trees, corners and traffic signals become authentic diaries for the dog. Indicate who has been there, what has eaten...
With such development of the sense of smell, normal that many dogs receive specific training to be able to detect bombs, or even alert of cancers in patients who don't know it yet. Not for nothing we say that it is our best friend...