Hearing a baby cry makes pets uncomfortable

Photo / Thinkstock

Hearing a baby cry makes people uncomfortable and new research has revealed it also stresses out man's best friend.

A recent University of Otago study has shown dogs, like humans, experience an increase in the stress hormone cortisol when they hear a human baby cry.

Psychology professor Ted Ruffman said the study, by former student Min Hooi Yong (who now lives in England), showed dogs were wired in a similar way to people in their reaction to hearing a baby cry.

The study will be published in the journal Behavioural Processes.

''It looks very much like empathy,'' Prof Ruffman said.

However, the response did not mean the dogs were aware the crying baby was in distress, he said.

''It is a very low-level form of emotional contagion.''

While other animals such as rats had been shown to have empathy for fellow rats, Prof Ruffman said this was the first study he knew of which showed ''cross-species'' - canine response to human distress - indication of empathy.

The study exposed about 74 people and 75 domestic dogs of many different breeds to three different sounds - a baby crying, computer-generated white noise and infant babbling.

After listening to the sounds for 13 minutes, saliva was taken from both and tested for cortisol levels which indicate empathy.

The white noise generated a stress response in both humans and dogs.

There was no response to babbling.

But only when hearing a baby cry did the dogs' cortisol levels increase and they showed signs of submissiveness and alertness.

Dogs' submissive response included lowering their head, the ears going back and flat, their tails lowered in some cases between the legs or wagging rapidly.

While many people were certain their dogs knew when they were upset, that had not been proven and their behaviour could be due to them seeking comfort when their owners retreated.

In this study, their owners were not distressed and the crying was coming from an alternative source.