Abstract: Fourteen dogs (7 males and 7 females) were tested for their heart rate (HR) and heart rate variability (HRV) responses in different activities and environmental challenges while their movement was controlled. First, we wanted to compare the dogs? cardiac responses in different body positions (lying, sitting and standing) and during slow walking to reveal their possible influence on HR and HRV. Second, we tested the HR response during an attentive state when the dog was gazing at its favourite toy while remaining in a steady body position. Finally we investigated the heart activity during separation from the owner. We also analysed the individual differences and the influence of gender on the heart responses. We found that the HR increased during periods of increased activity (walking) and was lowest during lying, while it did not differ between sitting and standing. At the same time no changes in HRV were found in the case of different body positions and walking. In contrast, HRV significantly increased when dogs oriented towards their favourite toy, and we found a distinct individual characteristic HR change in this situation compared to the similar body position without the toy being shown. Interestingly during separation from the owner the HR did not increase, but when a strange person was petting the dog, a significant increasing effect was seen in the HR. However the HRV increased only when the petting was discontinued. In general, large individual variation was found with regard to the HR and HRV, while gender did not influence the cardiac activity of the dogs.These results show that body position affected HR significantly in dogs. Further it seems that HRV could be a good indicator of the dog's attentive state. Thus in future studies both the physical and cognitive factors should be given more attention when HR or HRV is investigated as a dependent variable.