Scent - Pheremones and Odor
Compare the canine's nose Inside) to the human nose--it is much longer. The olfactory lobe of the canine is many times larger. Therefore, his brain's ability to register different smells is many times greater than ours. There are different nerves inside of the nose that register smell.
One particular gland (running the long way on the roof of the canines mouth, like a pancake) is affected by anything that may happen to the large canine teeth. An infected canine tooth, will seemingly, impair the canine's ability to smell. This makes it doubly important that the canine's mouth be kept healthy. You must pay very close attention to the canine's teeth because these scenting glands are so close to the large canine teeth.
There are many more "scenting cells" within the canines nose (cross section) than there are in a human nose. Any scent that travels up the canine's nose goes to all these "sensors" or scenting cells, and fits into the proper "scenting cell" for that particular scent molecule.
The nerves then transmit that particular scent molecules' message to the brain where it is then identified for the canine. To the best of our knowledge it is believed this transmission is by way of a very small electrical impulse that occurs when the scent molecule finds and fits into the proper scenting cell in the nose.
There is a volatile mucous on the inside of the nose. Scent then, to be registered by the canine's system, has to be water soluble. Example of a thing not soluble would be a bar of steel it will not dissolve in water. After scent molecules are dissolved in the mucous inside the nose, they are accepted by the scenting cells and the impulses occur that send messages to the brain.
One theory is that the molecules for each scent are different in shape. It is believed each molecule must "fall into" that scenting cell that is shaped to fit it or it will not be registered with the brain. This is called the "lock and key" theory. Another theory is that smell is a matter of each molecule of scent having a given radio frequency level. There is another little nerve, just under the nose, that can sense different radio frequencies. This theory is not too popular and is not proven. The "lock and key" theory is the one most widely accepted. What makes one person smell different from another? Scent is a combination of perspiration plus the bacteria (on the body) and this is "body odor". Deodorants kill the bacteria. Anti perspirants try to reduce the amount of sweat your body scent. This is because the water coming downward meets and obstructs the upward current of rafts. Thus, you always smell worse as you first leave a shower because you have held and accumulated the rafts for a few minutes.
Animals have the apocrine sweat glands over the entire body, but humans only has eccrine sweat glands all over the body. More odor, therefore, is produced on the animals body than on the humans. There is no difference in a canine trained to seek humans, or marijuana, or dynamite. The processes are the same, only the molecules look different for each as a matter of physical structure.
Adrenalin triggers different chemical changes within the body that come to the surface and mix with the sweat and smell differently when bacteria act upon them. Fear scent is what is called "pheromones", another very special scent put out by the body. If you step on an ant you will notice all the ants begin rushing around. what actually happens is that ants close by immediately secrete firmness. This is like a red flag coming up and saying "there is danger to the colony". This is how animals scent that danger is present.
Ants talk to ants with pheromones, but ants cannot talk to birds or other insects, etc. One species cannot smell the pheromones of another, except with the human. When we send out pheromones, other species can scent them we believe. This is the exception to the overall rule. The pheromone is a fairly recent subject of study.
Experiments are being made in using canines at mental hospitals to pick out schizophrenics because they emit pheromones constantly. The fear scent is strictly the pheromones. Anxiety and other emotions may produce a different smell or scent and are different from fear scent.
There are basically eight different chemical compounds in perspiration. There are five different kinds of bacteria that generally inhabits the human body at all times. What you have, then, is a combination of these eight chemical compounds and five kinds of bacteria comprising odor. As you can see, you can come up with a figure something like 5,565 different smells. By mixing the different chemical compounds, such as when you are afraid or guilty or whatever, you can give off different odors for each. This is why different people give off different odors when frightened, etc.
If you want to train your canine to pick out all the people who are afraid, you can do that. You can train him to pick out all the schizophrenics. A person feeling guilty is generally sweating from the aprocine glands. Another person probably would be sweating as much, but not from aprocine glands. Of course, the guilty persons odor is coming out like a smoke bomb and smells of "fear" (probably of being found).
The rafts, airborne with bacteria and sweat on them, still floating around in the air, picked up by the canine, are what is called "air" or "airborne" scent. The canine has his nose right up in the air and he is really watching those wind currents. If the rafts come to rest on the ground, it is what we call "ground scent". There is, unfortunately, some slight confusion in what is called a "tracking" canine and what is called a "trailing" canine. If some of the rafts have come to rest on the ground, they are going to be some distance away from the person, depending on the wind.
There is also the track left as the person steps on the ground, crushing and killing any plants there. When the plant is broken and crushed they excrete different fluids. As these fluids are released by the crushed plant, they interact with bacteria in the soil. Decay (soil bacteria working on the crushed matter) starts immediately. Therefore, footsteps in the above situation would smell differently from an odor produced by perspiration and bacteria. Herein lies the problem. Some canines are taught to follow the odor produced by the crushed vegetation and soil bacteria only (track only the footsteps) etc. How do you check this? Most attempts to track are across nice grassy fields. Try it across sand. There is no soil bacteria in sand. Also, sand is usually very hot and this kills off the bacteria on any rafts left by a person. Concrete or other paved or hard surfaces also lack the odor of soil bacteria working on the plant chemicals. So, if the canine is trained strictly to work on the odors left by the footprints, you may not find the right person.
So, what you want to train the canine to do is go on both sides of where you know the suspect) footprints to be and pick up the rafts that have settled to the ground downwind from the footprints.
A person who weighs the same and has the same shoe size can cross the suspects footprints and confuse the canine because he will cause the same chemicals to come from broken vegetation and set off the same footprint odor as the suspects. In experimenting, don't wait an hour or so before putting in a cross track. A canine can tell this because the bacteria will have had more time to create odor on the older track and the canine can tell this because the bacteria will have had more time to create odor on the older track and the canine can tell the difference. If the cross track is put in at almost the same time, the canine will be confused.
Experiment with this by having two people of same approximate weight and shoe size walk tracks that intersect at right angles at the same time. When they meet have each of them take the other's direction of travel to finish the track.
Then see if the canine will be confused when he gets to the crossing of the tracks. If he keeps on in a straight line you will know he is confused.
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