We talked about this very subject for weeks and quite in-depth. Believe me, I know the difference between cadaver dogs and air scent dogs and scent trail dogs and water dogs.
Air Scent Dogs
Pick up a scent and follow it, but not necessarily a certain person's scent. They don't work as well if other people are around (thus stopping volunteer searches, etc.)
Trailing Dogs
Use an item with a clean scent and follow scent on the ground. They'll only follow the scent of the particular person.
Tracking Dog
Follows a person's path, but doesn't use air scent. Often used when a scent item isn't available.
Cadaver Dog
A cadaver dog reacts only to the scent of a dead human.
Water Search Dog
A water search dog is trained to detect human scent that is in or under the water, they are trained to alert at the scent of body gasses. Usually done from a boat or shoreline.
There are also other types, but I don't think any of them would be used in a case like this. MOO
http://www.ussartf.org/dogs_search_rescue.htm
Also:
Three La Plata County Search and Rescue air-scent canines have conducted ground searches.
Dylan's mother gave investigators some of Dylan's clothing so canines know his scent.
http://www.kktv.com/news/headlines/S...tml?mobile=yes
Also, if you go back to 12/12/12 you will see many posts discussing this very thing.