In search dog work the age of the trail is one of the most important aspects of the search. The age of the trail is how old the footprints is in the sand or how long ago the person left the scent at the location.
In other words, if a person is missing 1 hour then the trail or track of scent they left behind is 1 hour old. When a person has been missing 15 minutes the trail has an age of 15 minutes.
As you and your dog gets close to the person the scent becomes fresher or hotter (younger). The further you are away from a person the colder or older the scent.
Your dog will react differently to cold and hot scents. A dog is usually more excited the hotter the scent and a dog is more inclined to slow down to study and work older scents. By watching your dog you can tell the age of a trail or scent.
Dogs are amazing in regard to how old of a scent they can find and follow. The Bloodhound is known as having a cold nose because they can follow cold trails as well as hot trails or tracks.
We might think a hot trail of scent would be easier for our dogs to follow but this is not the case because the scent particles have not settled and are floating around as a person moves. As the scent trail ages the particles settle on surfaces condensing into scent pools or trails that concentrate in one area or line of travel.
For this reason a dog can follow an older scent trail easier then a person who only moments before ran away. In training search dogs we want to make sure the dog is given every chance they can to achieve the goal of finding the lost person. With this in mind, you want to make reliable courses and trails for your dog to follow. The first training courses should always be prepared fairly simple for your dog to follow with the scent trail settled and aged.
Otherwise your dog will become disappointed and discouraged or confused by us asking them to follow a scent that is not reliable or consistent. From a dog’s point of view, a scent that is floating everywhere is difficult to follow.