Physiological Stress Responses in Dogs

The heart and respiratory rate of each animal were measured using a clinical stethoscope in the home environment before the behavioral tests and considered basal values. The same procedure was repeated in the novel environment immediately after the OFT and used as acute stress parameters. Additionally, saliva samples of dogs were collected by using a Sarstedt^® Salivette cotton swab in both environments to measure the cortisol levels of the dogs. All saliva samples were collected at the same time interval, i.e., between 10 and 12 a.m. Like other physiological measures, the saliva sample taken in the home environment was used as basal cortisol value, while the one collected 10 min after the OFT was used as an indicator for acute stress. It has previously been shown that approximately 10 min is needed after the induction of a stressor for a detectable increase in peripheral cortisol to occur^{76 (link)}. Saliva samples were transported at + 4 °C in sample containers and stored at – 20 °C until cortisol analysis. In order to avoid any food residue in the mouths of the dogs, dog owners were asked to restrict the food intake of their dogs starting two hours before cortisol sampling.