There are many different ways to use dogs for search and rescue operations.  Understanding these types can make the best use of search dog teams.  The main types of work the dogs can do are generally categorized as airscent (or wilderness), trailing, cadaver (land and water), and disaster.  Each of these types is explained in a little more detail below.

Airscent

Airscent usually refers to search dogs that use airscenting techniques to search areas.  Airscent dogs will ignore ground scent and will follow and locate people by catching the "hot" scent of people on the wind.  Airscenting techniques are very effective for covering large areas quickly and can produce high probabilities of detection if conditions are good for airscenting.  Some airscenting dogs are also trained to scent discriminate, meaning they can be pre-scented on an article from the missing persons and can pick this person from other in the search area.

Airscent dogs usually work off lead.  Airscent dogs are often called wilderness or area search dogs.  Most are trained to find the victim, alert the handler when the victim has been found, and the return the handler to the victim.  This is called a refind.

Trailing

Trailing or tracking usually refer to search techniques where the dog follows a ground based scent in order to find the victim.  The scent is left behind when people walk a particular path, and the dog is trained to follow these scent 'rafts" to the final location of the person.  While normally associated with Bloodhounds, many breeds of dog are used for trailing in search and rescue operations.  Trailing dogs are used in order to determine directions of travel as well as to locate victims by following their general path of travel.  Trailing dogs are usually scent discriminatory and can follow trails from several hours to several weeks old.

Cadaver / Human Remains Detection

HRD training refers to training the dog to recognize the scent of a deceased person.  JRD trained dogs are used in many search applications, from searching for long-missing victims to drowning victims.  HRD trained dogs are also used in many police based searched to pinpoint blood and other body evidence.  This is often called forensics HRD work.  Dog can be quite successful in locating the remains of a body, including small bones and teeth.  For water recovery work, dogs are trained to work from a boat and will indicated where the scent rises from the water.  This can help pinpoint search operations for dive and other recovery operations.  NASDA dogs perform a passive alert on JRD scent sources, which means they will locate the scent source, and perform a trained behavior which will not disturb the source.  Passive alerts generally consist of a sit, down, or bark.

Disaster

Disaster work is a variation of airscent work.  It combines the dog's ability to find a person with special training required to work in disaster conditions, including collapsed buildings, mudslides, earthquakes, and floods.  The disaster trained dog and handler spend a lot of time training control of the dog and directional control, so that the handler can send the dog onto rubble piles to perform closer searchers.  Both dog and handler undergo extra training for searching on unstable and dangerous surfaces.  The Federal Emergency Management Agency (FEMA) has a national program for disaster trained and certified dogs.

Articles

Some search dogs are trained specifically to find articles which may be clues associated with finding a lost or missing person.  These dogs basically use airscent techniques to cover the ground at close range, and can find small items the size of a quarter.  They often indicate articles by barking, or performing a specific trained behavior, such as a down.  Many dogs are also used in this capacity for police based work as well.