Conducting canine detection requires the handler to have a working knowledge of scent, including its origin and its transmission to, and behavior in, the environment.
Scent is produced when molecules from an object are dispersed into the air and register a sensory reaction in the brain. Molecules shed by the object become more and more dispersed as they move farther away.
Primary scent cone Mammals are able to detect both the presence and the relative concentration of scent. That is, they are able to discriminate and follow a pattern of increasing concentration to its source at the apex of the scent cone.
Interruptions to and enhancements of the spread of molecules from the source may distort the scent cone. The model of the ideal scent cone and the principles of environmental scent cone distortion constitute scent cone theory. It is essential that handlers have a solid understanding of the basic concepts; even well-trained canine will not perform well without a handler that can guide the process.
Handlers must analyze the operational environment to determine the potential for scent cone distortions. Based on this assessment handlers can anticipate the canines response and guide the canine appropriately.
An infinite number of environmental alterations or distortions can exist based on the terrain, vegetation, climate, season, and weather conditions. However, there are a number of principles of scent cone distortion that handlers must understand.
Additional Principles to consider:
- Water will move the scent away from the scent away from the source along scent conduits in response to gravity and/or currents, along surface or underground waterways, or following established erosion or drainage patterns.
- Wind or water flow can be altered by scent barriers, which may cause the formation of secondary scent pools, potentially forming a new, secondary scent cone remote for the target.
- Variable wind patterns can cause an uneven distribution of scent molecules in the air and scent cone distortion or breaks.
- Water flow along a conduit can interrupt the absorption of scent into the soil creating a scent void near the target at nose level.
- Elevation of the target with a horizontal scent cone can produce a scent void near the target a the canine's nose level.