A new study has found that dogs cry tears of joy when reunited with their owners after an extended period of time.
It’s long been thought that dogs love and bond with their humans just as much as humans bond with their dogs.
The love dogs have for their owners has largely been anecdotal, as pet parents claim to know in their hearts how much their dogs love them.
But now, science is confirming that idea thanks to researchers at the Laboratory of Human-Animal Interaction and Reciprocity at Azabu University in Japan.
A new study, “Increase of tear volume in dogs after reunion with owners is mediated by oxytocin,”
was published in the journal Current Biology shows a link between emotions and tears in dogs.
More specifically, it shows that dogs produce emotion-elicited tears when reunited with their owners after being separated for a period of time.
In a press release, the study’s lead author, Professor Takefumi Kikusui, explained that he first got the idea to research dogs’ tears when he noticed his poodle had teary eyes when nursing her pups.
“That gave me the idea that oxytocin might increase tears,” he said.
To test the idea, researchers measured dogs’ tear volume and determined the amount of tears produced before and after being reunited with their owners. In addition, they calculated the amount of tears produced when dogs interacted with strangers they didn’t know.
In the end, they found that dogs’ tear volume increased when they were reunited with a person they were familiar with.
Researchers also found that when they added oxytocin to dogs’ eyes, the tear volume increased. This supported their idea that oxytocin plays a role in tear production.
In the press release, Kikusui noted, “We found that dogs shed tears associated with positive emotions. We also made the discovery of oxytocin as a possible mechanism underlying it.”
“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!” he added.
We didn’t really need research to show us that our dogs love and care for us, but it’s nice to have science to back up what we already knew!