Heart rate and behavioural responses of dogs in the Ainsworth's Strange situation : a pilot study

The possibility of linking physiology and observable behaviour is of great importance in gaining a better understanding of the dog's reactions to environmental changes and potential stressors. Many studies of human-dog interactions explored the issues concerning attachment of people to their pets, whereas only few studies investigated the nature of the dog-human relationship or the dog's level of attachment to its owner. The aim of this study was to investigate dog's reactions to different emotional situations integrating physiological (heart rate) and behavioural measures. Seventeen adult dogs were tested in a 'strange' environment using a modified version of Ainsworth's Strange Situation Test. The procedure consisted of an introductory episode followed by eight consecutive experimental episodes in which the dogs were placed in an unfamiliar environment, introduced to an adult stranger and subjected to separations from the owner. During each observational session the behaviour of each dog was videorecorded and heart rate was measured in order to allow a comparison between heart rate and behaviour. The level of activity of each dog in each experimental episode was assessed recording 12 different behavioural categories. The heart rate values during the first experimental episode were analysed to obtain a baseline for each subject and the dogs' heart rate across episodes was assessed and compared to the baseline values. Furthermore, the effect of specific events (stranger's entrance and owner's return) on dogs' heart rate was evaluated. The results of the present pilot study show that socioemotional conditions induce changes in both behaviour and heart rate in adult dogs and that these changes, especially those at the behavioural level, indicate emotional stress.