Effect of rapid changes in environmental conditions on canine detection of methyl benzoate

Abstract

Detection canines are utilized worldwide in some of the most challenging field conditions for the detection of narcotics, explosives, and other targets. Much remains unknown, however, how these challenging conditions impact detection canine performance. Anecdotal evidence suggests that detection dogs require a “start-up” period – a short duration of time working – before performing optimally. These dogs commonly rest in climate-controlled settings (such as in a climate-controlled vehicle) and quickly transition to searches in contrasting conditions, which may exacerbate the issue. Accordingly, this study sought to quantify the magnitude and duration of the start-up period, and to identify any further effects on performance due to rapid transitions into extreme temperature/humidity conditions. The detection threshold of seven dogs was established for methyl benzoate (an odor simulant of illicit cocaine) under standard conditions using an air dilution olfactometer. A series of evaluations were then conducted to determine changes in this threshold when the dogs were rapidly transitioned from standard conditions to one of six temperature/humidity conditions - hot-humid, warm-humid, hot-dry, standard, cold-dry and cold-humid. Temperatures ranged from 0 to 40 ºC and relative humidity ranged from <40 % to >85 %. Changes in detection threshold were measured via a series of three “probes” of six trials, with a 2 min inter-probe interval to habituate to environmental conditions. Probes started at the dogs’ estimated threshold and decreased in concentration based on correct performance. Overall, dogs showed substantial decrements in the hot-humid condition followed by moderate decrements in hot-dry and warm-humid conditions. Cold conditions did not produce statistically significant decrements. In addition, the data indicate that a start-up period does exist when canines transition from a state of rest directly into a search assignment. The duration of this start-up period was initially measured to be several minutes long; but after the first series of testing (approximately a couple months of training/testing), the dogs only exhibited a decrement in performance on the first trial of a session. Overall, the results suggest that environmental conditions and a brief “start-up” effect should be considered as important variables that can impact detection canine performance.