Trial of evaluation of emotions using heart rate variability in free moving dogs

Heart rate variability (HRV) is a physical and noninvasive index of the autonomic nervous system and has been used in a wide range of fields such as human medicine, veterinary and animal behavior. Measuring devices have been improved miniaturization and light-weighting and they make it possible to measure a dog's electrocardiogram (ECG) under a free moving condition. HRV has been known as an index not only of physical activity but also to evaluate an animal's emotional status. One concern is a difficulty in dissociating physical activity and emotional status in HRV parameters. In this study, we examined how the physical activity component and the emotional component affect in HRV. We measured HRV and acceleration of the dogs under two conditions, the physical activity (motion) condition and the reward condition where food treats were emotional stimuli and under the motion condition. As a result, a dog's HRV values were linearly regressed on the acceleration data. SDNN (Standard Deviation of NN intervals) affected by the composite acceleration in reward condition while rMSSD (root Mean Square of Successive Differences) affected in motion condition. These suggested that the physical activity and HRV indices distribute on regression lines and emotional stimuli influences each HRV indices differently