“I Missed You!”

Those without dogs are often quick to dismiss the canine ability to feel emotion and express love. We dog lovers know otherwise—and now science has proved it. New research from Japan suggests that dogs actually tear up with happiness when reunited with their guardians after a long absence.

The researchers found the link between dog tears, happiness, and oxytocin, the so-called “love hormone.” Like us, dogs have tear ducts that produce tears to keep their eyes clean, but the link between tears and emotion had not been previously demonstrated.

Takefumi Kikusui, a professor at the Laboratory of Human-Animal Interaction and Reciprocity at Azabu University in Japan, began investigating dog tears after noticing one of his two Standard Poodles got teary as she nursed her puppies.

Through the study, they “found that dogs shed tears associated with positive emotions,” says Kikusui, who co-authored the research published in the journal Current Biology. “We also made the discovery of oxytocin as a possible mechanism underlying it.” It is still not known if dogs tear up in response to negative emotions, as humans do.

With the help of 20 dogs, researchers then compared the amount of tears before and after reunions with their owners, as well as other people the dogs were familiar with. Only the reunion with the owner increased the amount of tears.

The researchers also found that humans were more apt to take care of dogs with a teary-eyed look, hypothesizing that the tears may help cement the bond between human and dog. His team showed 74 people pictures of dogs’ faces with and without artificial tears in them and asked them to rank the animals. People gave more positive responses when they saw dogs with teary eyes.

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

This article originally appeared in the award-winning Modern Dog magazine. Subscribe today!