How Dogs Work

Human Remains Detection: Dogs in this category are trained to detect and find the scent of human remains. Cadaver dogs can find buried, submerged or fragmented human remains in all sorts of terrain. Lakes, swamps, collapsed structures and wilderness areas are no problem for the appropriately trained dog. Cadaver dogs can be used to find trace evidence and to search specific areas where human remains are suspected. All well trained dogs in this category can detect and alert the handler to a huge spectrum of human tissues including but not limited to; bone, bone fragments, teeth, blood, burnt and charred tissues and items that have previously been in contact with any of the above.

Trailing Search: Dogs in this category are trained specifically to follow the scent trail left on the ground by a subject. Trailing dogs can scent discriminate, and will only follow the scent of the subject in question while ignoring other individuals in the area. Trailing dogs use a scent article such as an article of clothing to follow where the missing person walked to allow searchers to find clues and deploy other resources in the direction the missing person traveled such area search dogs. Well trained dogs in this specialty can follow trails that were left by the victim several days prior to the search beginning with amazing accuracy.

(According to Bob Sessions Rescue Sept/Oct 1995)

The Nose Knows

How is an air-scenting dog able to detect the presence of a lost, hidden or completely confined subject? It all begins in the nose. Humans have approximately 5 million sensory cells in our nose dedicated to detecting scent. In contrast, canines have an estimated 125 to 220 million sensory cells to carry out the same function.

When air-scenting dogs zero in on a human scent, they’re really detecting dead skin cells. The average human body sheds approximately 40,000 dead skin cells a minute as normal biological function. These skin cells are covered with bacteria, even on a person stepping out of the shower. The bacteria eat and digest the skin cells, giving off a gas that we call body odor. This body odor, combined with other scents given off by the human, is what the air-scenting dog targets.

A grouping of shed skin cells is called a raft. A flake of dandruff is a recognizable raft. Larger rafts typically fall to the ground. This is what the bloodhound tracks. The smaller rafts, or individual cells, are light enough to be carried by the slightest movement of air. These rafts can travel great distances in open areas, or pass through small cracks, porous materials or crevices. They can even be carried through water to emerge on the surface. During movement, rafts continue to give off the gas generated by the bacteria.

by Bob Sessions