The journal Current Biology published a study by Japanese researchers who found that dogs are able to cry from overwhelmed emotions, reports The Guardian. "This is the first report demonstrating that positive emotions stimulate the secretion of tears in non-human animals", - the scientists said.
Study co-author Takefumi Kikusui of Azabu University said he was inspired to work by observing his own poodles. When the poodle became pregnant, the scientist noticed a particularly tender look in her, and looking closer, he realized that there were tears in the dog's eyes. “This led me to the idea that oxytocin (a hormone that causes a feeling of satisfaction and calmness next to a partner, - editor's note.) Can increase tearing. We have previously observed that oxytocin is released from both dogs and owners upon interaction”.
Scientists conducted an experiment involving 18 dogs, measuring their tear volume using a special Schirmer test in a normal home environment with the owner, as well as in a situation of meeting with him after a separation of more than five hours. It turned out that during the reunion, the secretion of tears was significantly more active. At the same time, when the dogs met with a familiar person who was not their owner, they did not cry with joy. An additional experiment showed that instillation of oxytocin into the eyes increased the amount of tears produced by the dogs, which was not the case when using another solution that did not contain oxytocin.
The authors of the study notice that dogs have acquired good communication skills in communicating with people using eye contact. Because of this, their tears are able to evoke in us response emotions - the desire to protect them and take care of them.
However, according to Kikusui, despite the results, the team still had questions: “We don't yet know if dogs shed a lot of tears during a reunion with another dog, and how they use tears to communicate with each other. It is necessary to clarify the social function of dog tears”.