You Are Not My Handler! Impact of Changing Handlers on Dogs' Behaviours and Detection Performance.

Dog-handler relationships can directly impact team success. Changing a dog's handler may therefore compromise detection performance. However, there are currently few studies which support this. This research explored the performance and behavioural impact of changing a dog's handler. Nine dogs trained at scent detection were accuracy tested with a familiar and unfamiliar handler. Both handlers were female with similar dog handling experience. The dogs were tested along brick lines containing target, non-target, and control samples. Testing was separated into four sessions, with each session having 36 samples. The dogs' accuracy scores were then calculated and testing footage behaviour coded. The dogs had significantly higher sensitivity ( = 0.045) and negative predictive value (NPV) ( = 0.041) scores when handled by the familiar handler. With the unfamiliar handler the dogs performed more stress-related behaviours, and were distracted for a higher proportion of time ( = 0.012). Time spent distracted was negatively correlated to detection performance (correlation = -0.923, < 0.001). With the unfamiliar handler the dogs' performance did not improve throughout testing ( = 0.553). This research demonstrates how these dogs' detection performances were impacted by changing handlers. Future research is required to determine if professional dog-handler teams are impacted similarly.