How dogs work
According to Johnston, dogs have the ability to use concentration gradient information to locate an odor source. The dog coming
into contact with the periphery of a vapor plume will initially encounter only relatively low concentrations of target compounds.
Dogs are also extremely efficient in processing information. Minimal sampling effectively guides them to rapidly deploy to
the odor source. Dogs are tasked to move from very low concentration gradients to higher vapor concentration gradients. Not
only are dogs able to detect target odors, but they can discriminate them from non-target odors, even when the non-target
odors are of higher concentration. Dogs are capable of learning a number of odor discriminations that can be demonstrated
interchangeably. Alhough most target odors are actually comprised of many different odor compounds, the dog is thought to
detect and respond to only a few and learn to recognize a substance in terms of its most abundant vapor constituents. In the
case of explosives, the most abundant compounds are solvents.
Besides the dog's sophisticated olfaction capabilities, the CDRI notes its other unique advantages over equipment technology.
The vapor wake detection dog is intended for use in venues attended by large numbers of people such as airports. The dog can
instantaneously sample plumes of air coming from persons and from what they are carrying through 'choke points' such as security
screening areas, ticket and gate areas.
Unlike stationary equipment, dogs are mobile and can maneuver through crowds. They are also psychologically a deterrent against
terrorist acts. Plus, dogs' vapor collection, signal processing and detection cycle times are instantaneous, and therefore
less likely to be foiled by terrorists. Unlike equipment and machines that may be compromised, each animal is different.
"With the inclusion of the Animal Health and Performance Program, the CDRI team is able to address not only detection dogs,
but bird dogs, retrievers, guide dogs and agility dogs," says Robert Gillette, DVM, MSE, Director of AAHP, CDRI and VSMP.
Through its research, the CDRI is also looking at the psychological component of a dog's performance, which can affect metabolic
function and its ability to perform its designated tasks. It was once thought that when you work or exercise an animal, you
were stressing the animal. But what the team is finding is that the work itself releases stress, and so the dog actually is
in a better state of mind while working or exercising.
Initially, when it was recognized that dogs had the ability to detect various substances, the effort was made to understand
the dog's capability and to try to design machinery and technology to mimic the ability. That was a portion of the mission
of the original IBDS. "What we found during the 1990s was that we can develop instrumentation that can perform some of the
tasks that a dog can do, but we've never been able to develop instrumentation that would beat the whole package of the dog's
capabilities," Gillette says. It is difficult to maneuver an instrument to determine where the source is — you have to take
a machine to the source. "Machines can be developed that detect certain levels of certain chemicals or odors, but we still
don't have the whole package," Gillette says.
Although according to regulations a dog can't invade the private space of an individual, that doesn't mean that a dog can't
smell air or vapors within a given area. "It's not our intention for the dogs to directly smell people," says Gillette. "In
large areas such as airports, train stations and event gatherings, what we can do is have the dog smell vapors within its
reach." The distance is somewhat dependent on many factors, especially how the scent is deployed from the source. For example,
in a subway location, the air moves within an enclosed space and in and out. This creates a different air flow than in an
open airport terminal.
In the case of the incident on Northwest Airlines flight 253, how close would a trained detection dog have to have been to
have picked up that explosive? Probably not that close. Certainly if vapor wake detection dogs were utilized in the airport,
they might be able to detect explosives within that environment, on persons or within a carry-on.
In the general case of the airport scenario, does the dog have to be within inches of its target? Not necessarily. "A dog
can be within 10 to 50 feet and can pick it up the scent," Gillette says. "Within any venue, such as an airport, if we can
find an area where there is a bottle neck, then that compresses the potential sources within the space where a dog can work,
scent or detect. Even if a person walking with an explosive backpack moved within an area, a dog-handler team could go into
that area at a later time, up to 15 minutes afterward, detect the device and follow that scent trail through the terminal
to where that person was standing."