A search-and-rescue dog is one trained to find missing people after a natural or man-made disaster. The dogs detect human scent and have been known to find people under water, under snow, and under collapsed buildings.
A dog with aptitude for finding dead bodies or body parts, whether buried, hidden or submerged, may be called a "cadaver dog". In Croatia such dogs have been used to find burial sites almost 3000 years old. Police, death investigators and anthropologists may work closely with cadaver dogs and their handlers. 
Training of a search dog is usually begun when the dog is still a puppy.
Numerous countries, cities and regions have search and rescue organizations using dog-and-handler teams that can be mobilized in an emergency or disaster. Here are a few organizations.