It travels differently in mountains than valleys, on rainy days than on clear days, in dry, cold air than in warm, moist air. Handlers must be aware of the differences in order to give the dog the best chance for success. Handlers of water search dogs must also know about currents that can carry bodies and affect the diffusion of scent. Training a dog to follow a particular scent begins with short sessions in which the dog finds his master. Gradually increasing the distance, the owner hides in the house or the yard, behind furniture or shrubbery, in all kinds of weather.
Next step is to work in unfamiliar terrain with the owner and to introduce other victims.
The dog must learn to find people when the tracks aren't fresh, so aged tracks must be used. And they must learn to pick up scents in a random pattern, for lost children and old people seldom travel in a straight line. Dogs doing land or disaster searches must learn to walk on debris, rocks, and other uneven surfaces. They cannot become so intent on the search that they cause more rubble to fall or end up a victim themselves. SAR jobs Local and federal law enforcement agencies use search dogs to seek out contraband such as smuggled food or drugs or to find bombs, to trail criminals, and to locate lawbreakers in a building.