The bond between man and dog is so close their hearts beat in sync when they are together, an astounding new study shows.
The heart rates of owners and their dogs become lower when they are in close proximity, an Australian experiment in which heart monitors were strapped to dogs and their owners found.
The discovery shows dogs have a fundamental role to play in lowering stress, says sports scientist Dr Craig Duncan.
Canine scientist and Monash University PhD student Mia Cobb says dog owners even recover more quickly from a heart attack.
Dr Duncan and Ms Cobb separated three dogs from their owners and placed heat monitors on humans and the dogs and monitored what happened when they were reunited.
The owner sat on a couch and when the dog entered the room and jumped up to greet its owner the heart rates of both lowered.
"I wasn't expecting how much they were synced and it surprised and impressed me," says Ms Cobb.
Dogs and humans have different heart rates but the study showed they dipped and sped up at the same rate while they were together.
The human's heart rate dropped by around 20 points and the dog's by around 40 points when they were united.
Ms Cobb says patting a dog releases oxytocin, a chemical that relieves stress.
"I look at stress and anxiety and how it affects human performance on a daily basis," Dr Duncan says.
"I also know personally the incredible toll it can take on your health. My heart attack was brought on by stress and it nearly killed me."