Dogs Shed Actual Tears Of Happiness When Reunited With Owners

A wagging tail, a loving, playful jump, a heart-melting gaze. You know when your dog is a joy to see you.

Japanese Scientist's New Research About Dog’s Eyes With Tears

Recent research from Japanese scientists suggests that a dog's eyes may end up with tears of happiness when reunited with its owner after a period of absence. The tears may cement the bond between human and dog, a relationship that goes into tens of thousands of years.

Like humans, dogs have tear ducts that well up with cry to keep their eyes clean and healthy. However, tears in dogs, which tend not to fall as when humans cry, hadn't been linked with emotion before.

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Dog Tears Investigation By Azabu University In Japan

Takefumi Kikusui, a professor at the Laboratory of Human-Animal Interaction and Reciprocity at Azabu University in Japan, confirmed to investigate dog tears after watching one of his two standard poodles when she had puppies six years ago. He detailed that her eyes got teary as she nursed her puppies.

We found that dogs shed tears associated with positive emotions, Kikusui, who co-authored the research published Monday in the journal Current Biology, said in a news release.

We also discovered oxytocin as a possible mechanism underlying it, Kikusui said, referring to the hormone that is sometimes called the love or maternal hormone in humans.

The Schirmer Tear Test

Kikusui and his team measured the number of tears among 18 dogs with a standard test called the Schirmer Tear Test to investigate the link. It includes a paper strip placed inside the eyelids of the dogs for a minute before and after reuniting with their owners following five to seven hours of separation.

The length of the wet part evaluated tear volume on the STT. The baseline was about 22 mm, and the rejoin with the owner increased by 10%, Kikusui explained via email.

With the help of 20 dogs, researchers compared the number of tears before and after reunions with their owners and individuals with whom the animals were familiar. Only the rejoin with the owner increased the number of tears.

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Oxytocin's Role In Producing The Tears

To understand whether oxytocin played a role in producing the tears, they applied a solution containing the hormone to the surface of 22 dogs' eyes. The tears significantly increased after they applied the oxytocin, compared with a control solution.

Also Read: An Eatery Offers Free Last Meals To Dying Local Dogs In Heart-Warming Gesture

There's still a lot the researchers do not know about dog tears. Humans often cry in response to negative emotions; however, researchers didn't test to see if dogs did the same. They do not know if a dog's ability to tear up plays a social function in the canine world.

Kikusui said it was possible humans would better care for dogs that got teary-eyed. His team showed 74 people images of dogs' faces with and without artificial tears 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, Kikusui said in a statement, and we can form bonds.