Dog's olfactory abilities
It is well known that dogs possess a highly developed sense of smell, which some estimates put as high as a million times more sensitive than that of humans. This is largely attributable to anatomical differences within the nose and brain.
The process of smelling begins with the ‘keying in’ of odour molecules to olfactory receptor cells, located within the epithelium lining an upper region of the nasal chamber called the olfactory cleft. These are connected via nerves to an area of the anterior portion of the brain known as the olfactory bulb. Whilst humans are served by about 5 million olfactory receptors, dogs have more than 250 million, in an area of nasal epithelium some 50 times larger. A correspondingly greater proportion of the dogs’ brain is devoted to processing the signals received from these receptor cells.
For centuries, man has made use of the scenting abilities of dogs to track people and animals. Today, dogs are used widely and successfully by police and customs services to detect drugs and explosives, and are increasingly being trained for other purposes, such as detecting dry rot and gas leaks in buildings. The training of dogs to recognise human cancer by its smell is in its infancy, but has the potential to make a contribution in the field of cancer.
Peer-reviewed papers on the effectiveness of dogs in odour detection work are surprisingly scarce, but a selection of some of the more recent is given below:-
Schoon GAA, De Bruin JC. The ability of dogs to recognise and cross-match human odours. Forensic Sci Int 1994;69:111-8.
Schoon GA. A first assessment of the reliability of an improved scent identification line-up. J Forensic Sci 1998;43:70-75.
Komar D. The use of cadaver dogs in locating scattered, scavenged human remains: preliminary field test results. J Forensic Sci 1999;44:405-408.
Furton KG, Hong Y, Hsu Y-L, Luo T, Rose S, Walton J. Identification of odor signature chemicals in cocaine using solid-phase microextraction-gas chromatography and detector-dog response to isolated compounds spiked on US paper currency. J Chromatogr Sc 2002;40:147-155.
Lorenzo N, Wan T-L, Harper RJ, Hsu Y-L, Chow M, Rose S, Furton KG. Laboratory and field experiments used to identify Canis lupus var. familiaris active odor signature chemicals from drugs, explosives, and humans. Anal Bioanal Chem 2003;376:1212-24.
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Related Links
See the encouraging results of our latest study published in the BJM:
» BMJ.com
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» cancerdogs.org
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