study
Dogs cry with happiness too
Dogs can also produce tears of joy, according to a new study. photo
© Patrick Pleul/dpa-Zentralbild/dpa
The dog is considered man’s best friend. When his mistress or master comes home, he happily wags his tail. And also in the eyes you can see it flashing.
Dogs can shed tears of joy when they see their master or mistress again. This is what a team led by the Japanese researcher Takefumi Kikusui from Azabu University in Japan writes in the journal Current Biology.
The scientists investigated whether not only humans, but also their four-legged friends sometimes cry when they are emotionally overexcited. “We found that dogs shed tears associated with positive emotions,” Kikusui said in a statement. Oxytocin, also known as the “cuddle hormone”, may play a decisive role in this.
Kikusui and colleagues made the discovery after one of his two poodles had puppies. While nursing her puppies, something changed on her dog’s face: the scientist says she had tears in her eyes. “That gave me the idea that oxytocin might increase tears,” says Kikusui. The hormone produced in the brain plays a major role in birth as well as in coexistence among people. It induces labor, stimulates milk production, strengthens the bond between mother and child, and can also strengthen couple bonds and build trust in other people among adults.
From earlier observations, the researchers working with Kikusui also knew that oxytocin is released during interactions in both dogs and their owners. They now wanted to find out whether dogs cry when they are reunited with their master or mistress. That was the case – unlike a person they didn’t know. Also, when they added oxytocin to the dogs’ eyes, their tears increased. Dogs, the researchers say, appear to produce tears in situations that humans see as “happy.” The question remains open as to whether dogs also cry when faced with negative emotions.