Dogs cry when they’re happy, sometimes doing it just to impress their favourite humans.

Japanese researcher Takefumi Kikusui of Azabu University noticed one of his poodles got teary while nursing her newborns and wondered if love was to blame – or more scientifically, oxytocin, which does the same thing to people (among a bunch of others that would be pretty awkward around a dog).

His team at Azabu University separated dogs and their owners, then tested how teary the canines got when they were reunited. They tried the same with dogs and strangers to see if that worked too.

“Tear volume indeed went up when they got back together with the familiar human and not with a person they didn’t know,” the researchers said.

Dosing the dogs with oxytocin increased the waterworks, leading Kikusui to conclude that after tens of thousands of years of domestication-driven evolution, they’re more like us than we think.

“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.”

Just a dog.
Barking or bawling? (Image: Pexels)

They weren’t mean enough to see if the reverse is true – whether dogs shed tears when they’re unhappy. Not this time, anyway.

In the same study, published in Current Biology, people shown pictures of dogs were more likely to positively respond if the dogs with teary eyes, suggesting it helps ” forge stronger connections between people and their dogs”.

“Dogs have become a partner of humans, and we can form bonds,” says Kikusui. “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.”