Results of the repeated measures ANOVA regarding the change of the cardiac responses of the whole sample of dogs.

<p>Significant differences are marked in bold.</p

Effects of the threatening approach on the HRV depending on the reactivity to the stranger.

<p>Changes in the mean heart rate variability (SDNN) of reactive and non-reactive dogs before, during and after the threatening encounter in the presence and absence of the owner. Dogs that growled or barked during the threatening encounter were categorised as behaviourally reactive.</p

Results regarding the change of the cardiac responses of dogs depending on their behavioural reactivity during <b>separation</b> (repeated measures ANOVA).

<p>Dogs that showed stress vocalisation during separation from the owner were categorised as behaviourally reactive dogs. Significant differences are marked in bold.</p

Results regarding the change of the cardiac responses of dogs depending on their behavioural reactivity during the <b>threatening approach</b> (repeated measures ANOVA).

<p>Dogs that growled or barked during the threatening encounter were categorised as behaviourally reactive. Significant differences are marked in bold.</p

Effects of the threatening approach on the HR depending on the reactivity to the stranger.

<p>Changes in the mean heart rate (HR) of behaviourally reactive and non-reactive dogs in the episodes before, during and after the threatening encounter in the presence and absence of the owner. Dogs that growled or barked during the threatening encounter were categorised as behaviourally reactive.</p

Effects of the threatening approach on the HRV depending on the reactivity to separation.

<p>Changes in the mean heart rate variability (SDNN) of behaviourally reactive and non-reactive dogs in the episodes before, during and after the threatening approach of a stranger in the presence and absence of the owner. Dogs that showed stress vocalisation during separation from the owner were categorised as behaviourally reactive dogs.</p

Effects of the test order on the HR in behaviourally reactive dogs.

<p>Changes in the mean heart rate (HR) of dogs that were reactive to the stranger in the episodes of the threatening encounter in the presence and absence of the owner in the two orders (A order: N = 8, B order: N = 9).</p

Set-up of the playback experiment.

<p>Set-up of the playback experiment.</p

Investigating Empathy-Like Responding to Conspecifics’ Distress in Pet Dogs

<div><p>Empathy covers a wide range of phenomena varying according to the degree of cognitive complexity involved; ranging from emotional contagion, defined as the sharing of others’ emotional states, to sympathetic concern requiring animals to have an appraisal of the others’ situation and showing concern-like behaviors. While most studies have investigated how animals reacted in response to conspecifics’ distress, dogs so far have mainly been targeted to examine cross-species empathic responses. To investigate whether dogs would respond with empathy-like behavior also to conspecifics, we adopted a playback method using conspecifics’ vocalizations (whines) recorded during a distressful event as well as control sounds. Our subjects were first exposed to a playback phase where they were subjected either to a control sound, a familiar whine (from their familiar partner) or a stranger whine stimulus (from a stranger dog), and then a reunion phase where the familiar partner entered the room. When exposed to whines, dogs showed a higher behavioral alertness and exhibited more stress-related behaviors compared to when exposed to acoustically similar control sounds. Moreover, they demonstrated more comfort-offering behaviors toward their familiar partners following whine playbacks than after control stimuli. Furthermore, when looking at the first session, this comfort offering was biased towards the familiar partner when subjects were previously exposed to the familiar compared to the stranger whines. Finally, familiar whine stimuli tended to maintain higher cortisol levels while stranger whines did not. To our knowledge, these results are the first to suggest that dogs can experience and demonstrate “empathic-like” responses to conspecifics’ distress-calls.</p></div

List and definitions of the coded behaviors.

<p>List and definitions of the coded behaviors.</p