The results of a new scientific study reveal that dogs do cry–and they cry the most when reunited with their human family members. Like humans at a wedding, the researchers say that dogs cry from positive emotions and that oxytocin (aka the “love hormone”) may be the impetus.
Earlier observations have revealed that oxytocin is released in both dogs and their owners during interactions. The researchers decided to run a reunification experiment and see if it brought dogs to tears.
The researchers used a standard test to measure dogs’ tear volume before and after reuniting with their owners. They found that tear volume went up when the dogs were reuntied with a human family member but not with a stranger. When the researchers added oxytocin to the dogs’ eyes, their tear volume also went up. That finding supports the idea that the release of oxytocin plays a role in tear production when dogs and their people get back together.
Researchers also asked people to rate pictures of dogs faces with and without artificial tears in them. Much to the surprise of the researchers, people gave more positive responses when they saw dogs with genuine teary eyes. These findings suggest that dogs’ tear production helps to forge stronger connections between people and their dogs.
The take away
The findings suggest that dogs produce tears in situations that humans consider “happy.” What has not yet been tested is whether dogs produce tears in response to negative emotions as well. Also still unknown is whether dogs make tears when they get back together with other dogs. This requires future research on the social worlds of dogs. What does appear to be the case from the current study are clear implications for the dog-human bond.
Journal reference: Murata, K., et al. Increase of tear volume in dogs after reunion with owners is mediated by oxytocin, Current Biology Journal, Volume 32, ISSUE 16, PR869-R870, August 22, 2022.