We all know how loyal dogs can be. While it can be hard to leave them, oftentimes coming home to their affection is a huge comfort after a long day. According to new research, it seems their joy extends beyond a wagging tail and gleeful jumps. The study shows that dogs actually shed tears of joy when they reunite with their humans after an extended time apart.
That's right. Pups can be so overjoyed to see their humans that their eyes actually well up. “We found that dogs shed tears associated with positive emotions,” Takefumi Kikusui, a professor at Azabu University in Japan, says. “We also made the discovery of oxytocin as a possible mechanism underlying it.” Usually referred to as the “love hormone,” oxytocin works the same in dogs as it does in humans. Meaning that it is released to strengthen bonds, which, in the case of canines, is with their owners.
Kikusui was inspired to start the study after noticing tears in his standard poodle's eyes when she was nursing her litter of puppies. He also notes that while dogs don't necessarily cry, their eyes do well up and even shed occasional tears. “We had never heard of the discovery that animals shed tears in joyful situations, such as reuniting with their owners, and we were all excited that this would be a world first!” Kikusui continues.
In the study, Kikusui and his colleagues measured different dogs' tear volumes prior to being separated from their owners and then upon their reunion. The results showed an increase in the tear volume after dogs were returned to their owners. Afterward, they performed another experiment, in which oxytocin was added to dogs' eyes. This also resulted in a higher tear volume. “Dogs have become a partner of humans, and we can form bonds,” Kikusui adds. “In this process, it is possible that the dogs that show teary eyes during interaction with the owner would be cared for by the owner more.”
A new study shows that dogs shed tears of joy when they reunite with their humans after long periods apart.