Tracking Dogs
Dogs who follow the actual footsteps of a person as closely as possible. They are usually discriminating ground disturbance as the smell to go on - crushed vegetation, disturbed dirt, ect. Many law enforcement dogs are taught this way - i.e. hot tracksh.These dogs may or may not be taught to scent discriminate. They just go after the most recent, most obvious scent. You need to try and start at the PLS ( point last seen.)
Trailing dogs
Dogs who follow human odor due to the skin rafts drifting off, odors from those cells, ect. These dogs will follow the trail of several feet to several yards away from the actual foot prints, depending on where the wind has taken the scent. Most trailing dogs are taught to scent discriminate, so the handler can tell the dog WHICH persons scent to follow. Trailing dogs work out much older tracks that tracking dogs. You would try to start at the PLS (point last seen)
Air scenting dogs
These dogs hunt for ANY human scent in a given area OR they can be taught to scent discriminate to look for a specific person. You usually try to have all the other searchers out of the dogs way , who runs off lead in a grid pattern. Indications that the dog has found someone range from a bark alert to a recall/re-find" which is where the dog located the victim and goes back to the handler, continuing this behavior until the handler reaches the victim.
Human remains/cadaver dogs