(CNN) – A wagging tail, a loving lick, a playful jump, a heart-melting gaze. You know when your dog is happy to see you.
Now, new research from Japanese scientists suggests that a dog’s eyes may well up with tears of happiness when reunited with their owner after a period of absence. The tears may help cement the bond between human and dog — a relationship that goes back tens of thousands of years.
Like humans, dogs have tear ducts that well up with tears to keep their eyes clean and healthy. But tears in dogs, which tend not to fall as they do when humans cry, hadn’t been linked with emotion before.
Takefumi Kikusui, a professor at the Laboratory of Human-Animal Interaction and Reciprocity at Azabu University in Japan, decided to investigate dog tears after watching one of his two standard poodles when she had puppies six years ago. He noticed that her eyes got teary as she nursed her puppies.
“We found that dogs shed tears associated with positive emotions,” Kikusui, who coauthored the research that published Monday in the journal Current Biology, said in a news release.
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