The number of olfactory cells in the membrane varies between 150 and 300 million depending on the breed, while in humans there are about 5 million. These olfactory cells which are located in the nasal mucosa and are responsible for collecting odorous stimuli, nerve cells are provided with a peripheral extension ending in cilia or filaments, which reach the surface of the nasal mucosa and are covered by a thin liquid layer secreted by glands called Bowman. This discharge has an important mission to capture and concentrate odorous substances in order to achieve this minimum energy stimulant that can produce the excitement of the olfactory receptors, called excitation threshold. The intensity of this threshold is influenced by multiple factors including the functional status of receivers and analyzers olfativosa central arousal, fatigue, stimulus characteristics (power, shape, duration, amplitude of the stimulated area…) , special types of environmental influences, etc.. To get to perceive an odor, the dog needs only the presence of nine thousand odorous particles, while the men are required approximately 7 billion particles. We can differentiate primarily in the canine olfactory sensory receptors and a total of three major nerves associated with these: olfactory trigeminal and vomerosanal.

– The olfactory nerve: response to small molecules and allows the dog get to discriminate the differences between thousands of odors. – The trigeminal nerve: supplies the olfactory function in case of failure of it and helps protect against harmful odorous stimuli. – The vomeronasal nerve: addresses to answer the larger molecules, such as pheromones.