The Dog’s Nose (1)
by Dr. Resi Gerritsen and Ruud Haak
Sense and Prickles
Thanks to his ancestors, the wolves, the dog possesses a highly developed olfactory system. Indeed most predators find their prey by smell. They also recognize family and enemies by the track they have left, their droppings, etc., so their olfactory system gives them information with a high survival value.
A sense is an organ that can pick up prickles from the outside world (for instance, recognizing prey or an enemy) or prickles from the body itself (hunger). These prickles then are changed into signals the brain can understand, which then provides the right response for the animal.
Functions of the Nose
M.D. Pearsall and Dr. H. Verbruggen described the functions of the nose:
1. As an airway, a connection from the outside world to the lungs.
2. As an ‘air conditioner’, by warming up or cooling down and moisturizing inhaled air. Lungs cannot exchange oxygen or carbon dioxide in dry surroundings.
3. As a filter to dispose of dirt, dust and irritants from the inhaled air.
4. As a source of reflex functions, like sneezing. Here the nose forms an early warning system to protect the fragile lung tissue.
5. As a sound box for barking or crying. The sinuses provide this.
6. As an organ to perceive odors. As a direction-finder. Both sides of the nasal cavity have an equal capacity to perceive odors. The littlest differences in intensity between these allows the odor source to be determined exactly.
For a better understanding of odor perception by dogs, it is good to first get a description of the anatomical structure of the olfactory system.
External Nose
The skull of dogs, like all mammals, consists of a frontal- and a nasal bone. The latter contains the olfactory system, the nose, in which we distinguish a front part, namely the external nose, and an internal part. The external nose carries out important functions, comparable to the functions of the external ear, that takes care of sound transmission.
The external nose picks up air turbulence and conducts odor substances to the internal nose. This picking up is stimulated strongly by the cartilage and strong, muscled structure of the forenose. The forenose is the lightly moist, bald part of the upper lip of the dog, usually black, although it can be brown, grey or rose depending, for instance, on the color of the coat. The surface of the forenose is characteristic for every dog. This is so specific, that a print of the fore-nose can be used for identification just like fingerprints are used for humans.
According to Prof. Dr. J. Bodingbauer, dogs with a large forenose are capable of greater scent achievements.
In the forenose are situated both nostrils, which are the entrance to the internal nasal cavities. With sniffing or more intensive smelling, the nostrils can be widened or narrowed, controlling the amount of air allowed in the nasal cavity. The muscles in the external nose of adult dogs, and in trained detector or tracking dogs, are strongly developed and because of that the external nose can be moved a little.
By sniffing, in combination with turns of the head and body, the dog can locate an odor source. This orientation will be stimulated by a moistened mucous membrane, formed by secretions of the Bowman’s glands. We do the same when we use a wet finger to determine the wind direction.
(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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Pearsall, M.D. and Verbruggen, H. (1982). Scent. Training to track, search and rescue. Alpine Publications, Loveland.
Bodingbauer, J. (1977). Das Wunder der Hundenase. Unsere Hunde, Vienna.
