This secretion has the important mission to catch the odorous substances and to concentrate them with the intention of reaching that minimum stimulating energy that gets to produce the excitation of the olfactory receivers, denominated excitation threshold. The intensity of this threshold is influenced by multiple factors as they are the functional state of the olfactory receivers and of the central analyzers of excitation, the fatigue, the characteristics of the stimulus (power, forms, duration, amplitude of the stimulated area. ), environmental influences of special type, etc. In order to be able to perceive a scent, the dog needs solely the presence nine thousand odorous particles, whereas in the man are necessary 7 trillions of particles approximately. We can basically differentiate in the canine sense of smell the sensorial receivers and a total of three nerves majors associated to these: olfatorios, trigmino and vomerosanal.
– The nerve olfatorio: it responds to small molecules and it allows the dog to be able to discriminate the existing differences between thousands of scents. – The trigmino nerve: it replaces to olfatorio in case of functional interruption of the same and aid to protect against injurious odorous stimuli. – The vomeronasal nerve: one takes care to respond to molecules of greater spread, as it is the case of pheromones. The parts of the canine brain that process and analyze the olfactory information, are the pineal lobe, the somestsica crust and the lmbico system, organs all located in the cerebral crust. The canine sense of smell besides presenting/displaying between 40 and 50 times but olfactory cells that the human, each cell of first has of 100 to 150 cilia, against 6-8 of human the olfactory cells. The cilium is an prolongation of the olfactory cell, that extended in the nasal snot, will be stimulated before the presence of the odorous cells. Consequently to greater number of cilia, major possibility of contacting with possible molecules odorous.
