Dogs cry happy tears when their owners come home

By Pol Allingham via SWNS

Dogs cry "happy tears" when their owners come home, according to a study inspired by a scientist's own pet pooch welling up with joy.

When Professor Takefumi Kikusui’s standard poodle had puppies six years ago he noticed the dog’s face changed when it nursed the puppies - it had tears in its eyes.

Prof Kikusui said: “That gave me the idea that oxytocin might increase tears.”

He explained that dogs produce tears, they just don’t fall like humans’ do.

Kikusui, of Azabu University in Japan, followed up his idea and discovered dogs had more tears in their eyes than normal when reunited with their owners, and their base level of tears didn’t change when they met someone they didn’t know.

When the researchers added oxycontin to the dogs’ eyes they filled up with tears too, supporting the theory that the release of oxycontin causes dogs to cry when they’re back together with their owners.

It was already known that the hormone is released in dogs and their owners when they play, but studying the reunification of the two is new.

The Japanese team also asked people to rate pictures of dogs’ faces with and without artificial tears in them, and people loved the teary-eyed pets more. This suggests dogs’ tears help forge stronger connections between people and their dogs.

Kikusui was surprised.

“We had never heard of the discovery that animals shed tears in joyful situations, such as reuniting with their owners, and we were all excited that this would be a world first!," he said.

He added: “Dogs have become a partner of humans, and we can form bonds.

“In this process, it is possible that the dogs that show teary eyes during interaction with the owner would be cared for by the owner more.”

The study, published in the journal Current Biology, showed dogs shed tears in happy situations, but they haven’t tested it on negative emotions yet.

The research team are yet to discover if dogs cry when they reconnect with other dog pals, but they hope to figure out if this tearful reaction also has a social function in the canine world.