Dogs Also Cry Out Of Happiness Because Of Oxytocin Or The “Love Hormone”

Oxytocin or the “love hormone” is produced in the human brain’s hypothalamus and released when we feel connected to other beings through the ability to develop empathy, love, and trust. The hormone is known to play a crucial role during childbirth and breastfeeding and also gets released during sex or something as simple as hugging or kissing a loved one.

Scientists have found that the neurotransmitter, oxytocin, is not something that is only produced in human brains. But when dogs experience positive feelings — like seeing their favorite human return home — they swell up with happiness and get all teary-eyed because of their brain’s ability to release oxytocin.

In a new study published in the journal Current Biology, lead author Takefumi Kikusui of Azabu University in Japan and colleagues demonstrated how the love hormone could make dogs teary-eyed whenever they feel happy or get excited.

“When dogs reunite with their owners, they exhibit highly affiliative behavior, including gazing at their owners, wagging their tails, jumping up, and licking their owner’s faces,” the researchers wrote in their paper. “Physiologically, oxytocin concentrations increase in dogs during a reunion with humans.”

The researchers worked closely with dogs, including a poodle named Kochi, who showed unbridled joy and excitement after seeing its owner return home following six long months of absence.

In the first experiment, the researchers measured the dogs’ tear volumes in their normal home environment when their respective owners were present and also within the first five minutes of a reunion after the dogs were separated from their owners for up to seven hours.

“Following separation from the owner in the dogs’ day care centers, dogs secreted larger tear volumes during reunions with their owners than with familiar non-owners, and tear volume during a reunion with the owner was significantly greater than the baseline tear volume,” the researchers observed.

Once this was established, they looked at oxytocin’s role in generating tears among dogs. For this, they made the human participants rate pictures of dogs’ faces that had artificial tears and other clear-eyed dogs. They also asked the humans to rate how much they would want to care for different dogs based on whether the dogs were teary-eyed or not.

“The dog photos with artificial tears were ranked significantly higher than the normal tearless dog photos,” the researchers noted.

“Unlike any other animals, 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 concluded.

“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 further leading to interspecies bonding,” they added in their paper.