The Dog’s Nose (2)
by Dr. Resi Gerritsen and Ruud Haak
Internal Nose
Separated by the nasal septum in the internal nose, there are left and right nasal cavities. The structure and the furnishing of the internal nose is by the so-called microsmatics (animals with a poor odor perception, like people, monkeys, chamois and birds) different of those which are the macrosmatics (animals with an excellent odor perception, for instance dogs).
In a microsmatic (osmé = smell), only a small part of the nasal cavity is given to the olfactory epithelium (regio olfactoria), while the biggest part is used for normal breathing.
The nasal cavity of a macrosmatic, like our dog, is a real labyrinth of folds (nasal conchae), which for the biggest part are covered with olfactory epithelium. Because of this labyrinth of nasal conchae, also called turbinates, the surface of the internal nose is greatly enlarged. These turbinates are situated from the side face of the nose to the septum, but have no connection with the septum. Like the rest of the internal surface of the nose, the turbinates are covered with mucous membrane that has a rich blood facility and contains sensory neurons (olfactory cells) on a lot of places.
In front of the nasal cavity we find the conchae maxillaris, of which the mucous membrane comparatively has fewer olfactory cells. The most important function of these turbinates is to warm and moisten incoming air. The mucous membrane of the conchae maxillaris contains many supporting cells with vibrating hairs on it, which keep the dirt out of the nasal cavity. Dirt that comes on these vibrating hairs will be moved away by their rhythmic movements.
Behind the conchae maxillaris we find the conchae ethmoidalis, which fills the rest of the nasal cavity. The mucous membrane of these turbinates contains large numbers of olfactory cells, which give the dog the ability to scan odors.
Sinuses
In the dog parts of the sinuses also have olfactory epithelium. In pups the sinuses are very small, but will grow as the dog gets older. ‘The sinuses are larger when the skull is bigger,’ Prof. K. Wagner (1930) wrote, and he added that ‘It looks like as if this characteristic especially is bound to the searching senses’.
Within the sinuses there are the maxillo sinus, situated directly above the mouth cavity in the area of the roots of the teeth. Infections in the upper jaw can cause infections in the sinus, affecting the ability to smell. The frontal sinus lays in the frontal bone; the olfactory epithelium is also in this cavity.
(to be continued)
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From: Dr. Resi Gerritsen and Ruud Haak, K9 Scent Training, A Manual for Training Your Identification, Tracking and Detection Dog.
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Wagner, K. (1930). Rezente Hunderassen. Eine osteologische Untersuchung. Oslo.
