Dog people will understand the angst suffered when parted away from your furry friend, and will also know that some dogs just have a hard time when left alone. But there might also be involved some tears. A new study showed that dogs produce more tears when reuniting with their owners.
The research, done by Japanese scientists, found that dogs that were separated from their owners for more than five hours had their eyes filled with tears when reunited and this could be linked to the increase of oxytocin, the “bonding hormone”.
According to the study, this could show that there is a relation between positive emotion and tear secretion in a non-human animal.
To get to this conclusion, Professor Takefumi Kikusui, co-author of the research at Azabu University, told the Guardian that he noticed how one of his poodles had a different expression when nursing her puppies and realized that her eyes were teary.
“That gave me the idea that oxytocin might increase tears,” he said. “We previously observed that oxytocin is released both in dogs and owners when interacting. So we conducted a reunion experiment.”
The study consisted of measuring the volume of tears 18 different dogs produced while in their normal home environment. To do so, they used a special strip of paper and measured how far long the moisture had been.
Then, these strips were compared to others that were used to measure the volume of dogs that had been reunited with their owners after five hours of separation.
Researchers noticed that when reunited with their owners, dogs produced a significantly greater volume of tears. This increase was not seen in 20 dogs that were reunited with a familiar human that was not their owner.
Researchers believe dogs use tears as a way of communication with humans since they can “play a role in eliciting protective behavior or nurturing behavior from their owners,” they wrote, and that it can help create a deeper relationship between humans and dogs.
The study is still in its early stages. Scientists hope to keep studying the tears in dogs to see if this happens as well when they reunite with another dog friend or in any other situation.
