A study reveals that dogs shed “happy tears” when their owners return home after being apart for an extended time.
According to the study published in Current Biology, Japanese researchers observed the behavior of 22 dogs, comparing their reactions before and after reuniting with their owners and other people they knew.
To test their theory, researchers placed paper strips under the dogs’ eyes during routine interactions with their owners. After five to seven hours of separation, they repeated the process just before reuniting the dogs with their owners.
The results showed that when dogs see their owners after long hours of separation, that is the only time they shed tears.
Moreover, the increase in tear production was significantly higher when dogs reunited with their owners compared to when they met other familiar people.
The researchers suspected that the tears were linked to their emotions, which is why they applied a solution containing oxytocin, also known as “love hormone” involved in bonding. After using the hormone, they found out that the dogs’ tears significantly increased.
“We had never heard of the discovery that animals shed tears in joyful situations, such as reuniting with their owners,” said Takefumi Kikusui, one of the study’s co-authors. The study suggests that a dog’s tears might play a role in the deepening of mutual relationships with their owners.
So, the next time you see your dog’s eyes glistening when you walk through the door, it’s not because of something in their eye—it’s because of the love and bond you share.
