Dogs cry tears of joy when reunited with their owners – proof of the strong emotional bond between humans and their canine companions, according to a new study. Dogs have tear ducts that flood with happiness in a variety of situations, including seeing their owners for the first time after long periods of absence, according to researchers in Japan. “We found that dogs shed tears associated with positive emotions,” Takefumi Kikusui, from the Human-Animal Interaction and Reciprocity Laboratory at Azabu University, said in a statement. “We also made the discovery of oxytocin as a possible mechanism behind it,” Kikusui said, referring to the so-called love hormone, which produces warm, fuzzy feelings. During the study, published Monday in the journal Current Biology, Kikusui and his team placed paper strips known as the Schirmer Tear Test inside the eyelids of 22 dogs. They then measured the amount of tears the dogs produced for one minute before and after being reunited with their owners after being separated for five to seven hours. A new study shows that dogs shed tears associated with positive emotions.Getty Images After the owner returned, the tears they produced increased by an average of 10 percent, the researchers said. Instead, the researchers did the same thing with people who didn’t own canines and found that the dogs’ tears didn’t increase at all. To examine the role oxytocin played, the researchers placed a solution containing the hormone in the animals’ eyes and found that the number of tears increased significantly after the liquid was added, according to the study. The researchers used people who were not dog owners to see how the study would change. Getty Images/Cavan Images RF Kikusui said he was inspired to research the cause of Fidos’ emo eyes after seeing one of his poodles tear up while nursing her puppies six years ago. The researchers said they still don’t know whether, like humans, dogs cry when they are experiencing negative emotions. And they don’t know if a dog’s tears serve a social function in the canine world. But Kikusui said the study shows, “Dogs have become people’s companions.”
