Dogs Produce Tears When They're Reunited with Their Owners, Study Finds
Michelle Milliken
Are you happy to see your dog after you've been away on vacation, or maybe even after a day's work? They may just feel the same way.
A new study conducted by researchers in Japan and published in Current Biology discovered that in addition to wagging tails and smiling faces, something else happens when a dog sees its human after a bit of an absence: teary eyes. This appears to be due to a hormone linked to happiness.
Takefumi Kikusui, study co-author from Azabu University, says, "We found that dogs shed tears associated with positive emotions. We also made the discovery of oxytocin as a possible mechanism underlying it."
Kikusui says he was interested in investigating this link between happiness and tears in dogs after his poodle had puppies. Whenever she was nursing them, she appeared to tear up, which made him think that oxytocin may increase tears.
The team says past studies had shown there was oxytocin released during interactions between dogs and owners. To build on this, the researchers measured dogs' tear volume before they were reunited with their owners, and then again afterward. In so doing, they learned that tear volume increased during these interactions with their owners but not with strangers.
The team also added oxytocin to dogs' eyes to see if tears were produced, and they were. The researchers say this shows that the happy hormone oxytocin may be behind the teary eyes of pooches happy to see their owners.
Kikusui says, "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!"
Another finding? Those teary eyes could endear our pups even more to us. The team asked people to rate pictures of dogs, and participants ranked dogs with artificial tears in their eyes more positively than those without them.
The team hopes to see if dogs can have the same reaction when reunited with their fellow pooch friends, too. Until then, just remember that your happiness on seeing your dog's face after an absence is likely returned.
