Dogs cry with gladness when greeting their humans
People often cry tears of joy in the throes of emotion. A new study shows that dogs do, too: they become teary-eyed when they are reunited with their owners1.
When a dog and its owner lock eyes, both produce oxytocin, the ‘love hormone’ associated with emotional bonding, according to previous observations. Scientists have speculated that a pup’s tearful eyes might make humans want to care for the creature.
To examine this, Kaori Murata at Azabu University in Kanagawa, Japan, and her colleagues separated 18 dogs from their owners and, on reuniting the pairs several hours later, measured the volume of the animals’ tears. They also applied oxytocin to the dogs’ eyes to see if the chemical induces waterworks, and asked people how they felt while looking at photographs of wet-eyed dogs.
The dogs’ eyes moistened when the animals greeted their owners. Adding oxytocin also resulted in tear production, leading the researchers to suggest that this hormone mediates the emotional response. Moreover, people associated more-positive emotions with tearful dogs than with those with dry eyes. The authors say that this is the first study documenting happy tears in a non-human animal.
doi: https://doi.org/10.1038/d41586-022-02280-z
References
Murata, K. et al. Curr. Biol. 32, R1–R3 (2022).
