Most of us have seen search and rescue dogs locating lost children on television shows.  On TV, dogs use any means possible to find a lost person, from sniffing for human scent in the air to sniffing an article of clothing and tracking that individual's unique scent.

While search and rescue dogs are capable, in principle, of being trained as both air scent and trailing dogs, most dog handlers train their dogs to perform only one of these disciplines.  Therefore, the most valuable dog team, in terms of obtaining a high probability of detection, is one with a dog that can switch back and forth between air scenting and trailing as conditions dictate.

All humans, alive or dead, constantly emit microscopic particles bearing human scent.  Millions of these are airborne and are carried by the wind for considerable distances.  

AIR SCENT DOGS

The air scent dog is the type most frequently encountered.  This dog finds lost people by picking up traces of human scent that are drifting in the air, and looks for the "cone" of scent where it is most concentrated.  This dog will not normally discriminate scents, so there is the possibility of a "false alarm" if other people (searchers, citizens) are nearby.  Airscent dogs work best in situations such as large parks or private lands that are closed at the time, since the dog will home in on any human scent.  The success of an air scent dog will be affected by a number of factors, including wind conditions, air temperature, time of day, terrain, and presence or absence of contamination (auto exhaust, smoke, etc.).  The best conditions for air scent dogs to work are early mornings or late afternoons on cool, cloudy days when there is a light wind. 

TRAILING DOGS

The trailing dog is often referred to as a "tracking" dog, although "tracking" and "trailing" are not the same to the purist.  The trailing dog is directed to find a specific person by following minute particles of human tissue or skin cells cast off by the person as he or she travels.  These heavier-than-air particles, which contain this person's scent, will normally be close to the ground or on nearby foliage, so the trailing dog will frequently have its "nose the ground," unlike the air scent dog.

A Bloodhound is typically trained for scent discrimination.  Each dog is usually worked in a harness, on a leash, and given an uncontaminated scent article (such as a piece of clothing) belonging to the missing person.  The dog follows that scent and no other.  At times, the dog may track, following the person's footsteps, or air scent, and home in on the subject's scent. 

Field contamination (scent of others) should not affect his work.  He should be able to trail scents on pavements, streets, grass, water, etc.  If there is a good scent article and a point where the person was last seen, a trailing dog can be the fastest way to find the victim.  Without the scent article and a point where the person was last seen, these dogs cannot work effectively.
   
While those are the two standard types of search and rescue dogs, there are also other dogs trained to find lost people.

TRACKING DOG

A tracking dog is trained to follow the path of a certain person.  It physically tracks the path of the person, without relying on air scenting.  This dog is usually worked in a harness and on leash. This type of dog is effective when pursuing an escaped criminal if no scent article is available.  These dogs are also used successfully in search and rescue operations.

DISASTER DOG

A disaster dog is trained to find human scent in very unnatural environments, including collapsed structures and areas effected by tornadoes, earthquakes and other disasters.  This dog is trained to work on unstable surfaces, in small, confined spaces and other settings not usually found in the wilderness.

CADAVER DOG

A cadaver dog reacts to the scent of a dead human.  The dog can be trained for above ground and buried cadaver searches.  Although many dogs have the potential to detect human scent, whether dead or alive, the cadaver dog is trained to locate only human remains.  The training process includes detection of very minute pieces of cadaver or even blood drops in a specified area.

WATER SEARCH DOG

A water search dog is trained to detect human scent that is in or under the water, focusing on the scent of the bodily gases that rise up.  As a team, the handler and dog usually work in a boat or along the shoreline.  Because of currents and general changes in the water, it can be hard to pinpoint the location of a body.  To enhance the chance of location, a diver should be ready to search as soon as the dog indicates.  Additional teams, unaware of the previous teams' findings, work independently to indicate a location.   This allows team members to determine the most likely location of the body.

AVALANCHE DOG

An avalanche search dog is trained to detect human scent that is in or under snow, subsequent to an avalanche.  These dogs are trained to detect the scent under many feet of snow, sometimes, 15 feet or more!

WHAT TO DO IF YOU ARE LOST

To enhance your chances of survival, make it easy for the searchers and their canine partners to find you.  If you get lost, STAY PUT.  Your chances of survival increase if you don't wander around.  You can aid the human searchers by placing easily seen colored items at eye height and in open areas which can be spotted from the air.

Family members SHOULD NOT handle belongings owned by the lost person. Once they do, the items are contaminated and cannot be used by a trailing dog.

Establishing priorities if you are lost, especially if you are lost long-term, is one of the first steps to survival.  Basic needs are food, fire, shelter and water.  Shelter is usually required first, but this can depend on where you are and individual circumstances.  An adult can survive for three weeks without food, but only three days without water.  Never wait until you run out of water before you look for more.  Conserve your supplies.   Remember that the human body loses 4-6 pints of water each day.  Loss of liquids through respiration and perspiration increases with work rate and temperature.  This must be replaced by actual water or water contained in food.  You can retain fluids and keep loss to a minimum by avoiding exertion, not smoking, keeping cool, staying in shade, not lying on hot ground, eating as little as possible, breathing through the nose and not drinking any alcohol.

Considering all of the above, always attempt to remain in the area in which you were first "lost" to make it easier for the rescue party and the specially trained canine to locate you.