Types of Detection Dogs--How Many Can You Name?

When I began working on Service and Therapy Dogs in American Society, I was soon struck by the proliferation of service dog types, including the fairly recent category of hypoglycemia alert dogs and the still anecdotal migraine-alert dog category. This is nothing compared to the list of scenting dogs that were assembled by a group of chemists in 2004. They came up with 30 scent detection dog categories. Some of these categories probably only represent a few dozen dogs, but many of them are essential to law enforcement and are found throughout the world. The categories are:

1. Abalone (endangered mollusk poaching) detector dog
2. Agricultural product (importation) detector dog
3. Arson (accelerant) detector dog
4. Brown tree snake (pest species) detector dog
5. Airport/runway detector dog
6. Cadaver (human remains) detector dog
7. Chemical weapon detector dog
8. Citrus canker detector dog
9. Concealed person detector dog
10. Currency detector dog
11. Drug (narcotic) detector dog
12. Explosives (bomb) detector dog
13. Gas leak detector dog
14. Gold ore detector dog
15. Gun/ammunition detector dog
16. GYPSY moth larvae detector dog
17. Land mine trip wire detector dog
18. Melanoma detector dog
19. Missing person detector dog
20. Rotten power pole detector dog
21. Scent line-up detector dog
22. Screw worm detector dog
23. Seal detector dog
24. Search and rescue (warm blood) detector dog
25. Syringe needle (dried blood) detector dog
26. Termite detector dog
27. Tracking (fleeing suspect) detector dog
28. Truffles detector dog
29. Water search detector dog
30. Wildlife detector dog

The list was compiled for an article in the Journal of Analytical and Bioanalytical Chemistry. Lorenzo, N., Wan, T.L., Harper, R.J., Hsu, Y.L., Chow, M., Rose, S., and Furton, K.G. (2004). Laboratory and Field Experiments Used to Identify Canis lupus var. familiaris Active Odor Signature Chemicals from Drugs, Explosives, and Humans. Analytical and Bioanalytical Chemistry, 376: 1212-1224.

For more on the use of detection dogs in conservation projects, see Brown, C., Stafford, K., and Fordham, R. (2006). The Use of Scent-Detection Dogs. Irish Veterinary Journal, 59(2), 97-104. dogs have been used to find dead bats at wind farms. Arnett, E.B. (2006). A Preliminary Evaluation on the Use of Dogs to Recover Bat Fatalities at Wind Energy Facilities. Wildlife Society Bulletin, 34(5), 1440-1445. They have also been trained to detect microbial growth in buildings, which can cause respiratory and other symptoms in occupants. Kauhanen, E., Harri, M., Nevalainen, A., and Nevalainen, T. (2002). Validity of Detection of Microbial Growth in Buildings by Trained Dogs. Environmental International, 28, 153-7. A master's thesis filed with South Dakota State University studied dogs trained to find ferrets. The thesis was adapted into an article Reindl, S.A. et al. (2006). Efficacy of Scent Dogs in Detecting Black-Footed Ferrets at a Reintroduction Site in South Dakota. USDA National Wildlife Research Center Staff Publications; Kerley, L.L. and Salkina, G.P. (2006). Using Scent-Matching Dogs to Identify Individual Amur Tigers from Scats. Journal of Wildlife Management, 71(4), 1349-1356 (a unique study in that the dogs were not trained just to recognize tigers, but also to identify individual tigers).

In the Federal Register of October 2, 2013, the Fish and Wildlife Service reported that dogs had been used in an attempt to identify and locate potential natural roosts of the bonneted bat in Florida. 78 Fed. Reg. 61004 (October 2, 2013), at 61007 and 61018.  The dogs were obtained from Auburn University's EcoDogs. 

Scenting Skills Now Part of Genetic Research on Dogs

We shed 30,000 to 40,000 skin flakes each minute. (Picture shows electroni microscope image of a desquamated skin flake, at least a thousand of which you'll shed by the time you finish reading this piece.) Clothing is permeable to this particle stream and it comprises between 70% and 90% of house dust. These skin flakes spread up and out from the body by heat and air currents in a pattern known as a plume, and are a major part of the scent trail that a tracking dog follows. (See Gary S. Settles, “Sniffers: Fluid-Dynamic Sample for Olfactory Trace Detection in Nature and Homeland Security—the 2004 Freeman Scholar Lecture,” 127 Journal of Fluids Engineering 189 (March 2005); Robert Hunt, “The Benefits of Scent Evidence,” FBI Law Enforcement Bulletin, p. 15 (November 1999).) How the olfactory systems of dogs work is a study in itself, as are the fluid dynamics that describe the dissemination of the plume—how far and how quickly it spreads. Dogs can generally find scent trails within 48 hours after the target has been in an area but much longer periods have been reported. An FBI newsletter describes a case where a bloodhound followed a trail from a car abandoned 17 days earlier to a suspect’s apartment building. This dog was even able to follow the 17-day old trail into a commuter station to a kiosk where the suspect caught a bus. The dog was thus able to ignore the scents of thousands if not tens of thousands of commuters in tracking the suspect. (Guy J. Hargreaves, “Detection Dog Lineup,” FBI Law Enforcement Bulletin (January 1996).) Another area of research on dog scenting concerns the dog genome. In 2008, a team of Polish scientists determined that variations in olfactory receptor genes “might affect the olfactory ability of service dogs in different fields of specific substance detection.” Twin dogs with a specific gene variant were able to track better than other dogs with different variants of the gene. (A. Lesniak, M. Walczak, T. Jezierski, M. Sacharczuk, M. Gawkowski, and K. Jaszczak, K., “Canine Olfactory Receptor Gene Polymorphism and Its Relation to Odor Detection Performance by Sniffer Dogs,” 99(5) Journal of Heredity 518-527 (September/October 2008).) Thus, it might soon be possible to predict, both for cancer sniffers and other detection dogs, whether a puppy is a good candidate for such work. It might even be possible to select for genetic predisposition to high tracking skills in breeding programs. Whether that kind of dog breeding will be a good thing I am not sure, but I have no doubt that someone will make it part of a breeding program sooner or later.