Dogs have been humankind’s best friend for millennia, offering us companionship and affection. Our furry friends also benefit from this relationship since we give them love and care in return. A new study by Japanese researchers found that dogs can cry tears of joy when reunited with their owners.

Researchers found that dogs experience an intense emotional response during human interactions. Canines cry joyful tears most often when they reunite with their owners. However, they also become teary-eyed while cuddling or receiving pets from humans. It seems that the “love hormone” causes this heartwarming response, according to the research.

“We found that dogs shed tears associated with positive emotions,” said Takefumi Kikusui of Azabu University in Japan. “We also made the discovery of oxytocin as a possible mechanism underlying it.”

Kikusui and his colleagues made the findings after one of his two standard poodles had a litter of puppies. He observed that the dog had tears in her eyes while she nursed her newborn pups. The tears didn’t roll down her cheeks as they do in humans but welled up in her eyes.

“That gave me the idea that oxytocin might increase tears,” Kikusui says.

Earlier experiments discovered that both pups and humans release oxytocin, the maternal hormone, during interactions. This time, researchers wanted to investigate whether dogs would cry when reunited with their owners after a few hours apart.

Their findings appeared in the journal Current Biology

Study Shows That Oxytocin Makes Dogs Cry Happy Tears


For the study, researchers measured canines’ tear volume before and after reuniting with their owners. The dogs and their humans spent about five to seven hours apart for the research. The team discovered that their tear volume increased during reunions with a familiar human but not with a stranger.

Next, they added oxytocin to the dogs’ eyes and observed that this made the canines cry more. The experiment confirms that the hormone oxytocin causes dogs to cry when they see their humans.

Kikusui said the findings came as a surprise. “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!”

Finally, the team showed people two photos of each canine: one with artificial tears produced by a saline solution and an unaltered picture.

“Ten photos from five dogs were randomly presented on the computer screen, and the participants scored on a five-point scale from positive (want to touch, and give some care) to negative (fearful and avoid) for each photo,” the study authors said.

Humans Prefer Dogs With “Puppy Eyes”

Most participants reported having a significantly greater desire to care for the dogs with “puppy eyes.” Pups seem to have learned the trick to getting their owners’ attention!

The hormone oxytocin elicited an emotional response in the participants and heightened their urge to connect with the dogs.

“Unlike any other animal, dogs have evolved or have been domesticated through communication with humans and have gained high-level communication abilities with humans using eye contact,” the researchers wrote.

“Through this process, their tears might play a role in eliciting protective behavior or nurturing behavior from their owners, resulting in the deepening of mutual relationships and leading to interspecies bonding,” they continued.

In the study, researchers observed that pups cry during positive human interactions. However, the team still doesn’t know whether dogs cry when they also experience sadness. They also haven’t yet tested if canines produce tears when reuniting with their canine friends. In the future, they aim to discover if tears play a role in social interactions between dogs.

For now, researchers know that puppy dog eyes can melt humans’ hearts and strengthen the bond between both species.

“Dogs have become a partner of humans, and we can form bonds,” said Kikusui. “In this process, it is possible that the dogs that show teary eyes during interaction with the owner would be cared for by the owner more.”

Seeing a dog cry joyful tears in your presence can brighten even the darkest days. Canines also show their love in other equally adorable ways that we will list below.

Three Key Signs That Your Dog Loves You

  • They give you licks and kisses: Behavioral experts say that dogs offer their owners kisses as a sign of submissiveness. Since you’re the one who feeds and cares for them, they see you as the dominant member of the “pack.” Dogs also give kisses to their human family to show affection and appreciation.
  • Your dog cuddles with you: Nothing feels better than snuggling with your dog after a stressful day at work. Studies reveal that petting canines can decrease stress and anxiety, another reason to appreciate the furry friends in our lives.
  • They jump up and wag their tail when you come home: Your pet will anxiously await your return when you’re gone all day at work or school. If you walk in the door and they immediately jump on you, that’s a clear sign of unconditional love! They may also greet you by wagging their tail or wiggling back and forth in excitement.

Here is a fun bonus fact about pups. Did you know that their heart rate increases when you say, ‘I love you?’ A canine behavioral expert discovered that dogs’ heart rate jumps 46.2% when they hear those three words. We don’t know what will if that doesn’t melt your heart!


Final Thoughts on Study That Reveals How Dogs Cry Tears of Joy

If you ever see your dog cry, don’t become alarmed. It just means your best friend feels overjoyed to see you! Or, if your canine just had puppies, she might shed happy tears at the thought of being a mom. Japanese researchers found that dogs cry in response to oxytocin, the “love hormone.” They found that dogs produced more tears when they reunited with their owners after several hours apart.

Also, the study authors determined that humans felt a stronger urge to care for dogs with “puppy eyes.” It seemed that when participants saw a dog cry, it also increased their oxytocin levels.