We’ve all seen happy videos of dogs jumping for joy when their owner returns home, but their emotions may go even deeper than previously thought. It turns out, dogs can likely cry tears of joy.
A new study by Japanese scientists suggests that dogs may produce tears of happiness when their human returns to them.
The researchers measured the tears of 18 dogs who were reunited with their owners after five hours apart. They then compared them to those they produced when united with a familiar human who was not their owner.
The study found that the dog’s volume of tears was higher when they were reunited with their owner, indicating that it was them specifically who generated an emotional response.
The tears appear to be linked to oxytocin, which is known as the “bonding hormone.” Researchers also found that dogs produced significantly more tears when reunited with their owner after time apart than when they were both together in their house.
Takefumi Kikusui, a professor at Japan’s Azabu University, co-authored the research. He first noticed a possible link between happiness and tears in dogs after seeing his pet poodle seemingly well up when nursing her puppies in 2016.
The research is the first of its kind ever to demonstrate that non-human animals are able to cry due to positive emotions.
“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 authors 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 further leading to interspecies bonding.”
Recent studies on dog behavior
This isn’t the first study this year to give us more insight into our canine companions.
Research published back in April found that, despite previously held conceptions, dogs’ behavior often isn’t linked with their breed.
Many people will be aware that dogs like pit bulls, Rottweilers, and Staffordshire terriers are often thought of as aggressive, while Labradors and Golden Retrievers are seen as more happy and friendly. The research, however, cast doubt on these assumed truths.
Researchers from University of Massachusetts UMass Chan medical school analyzed more than 18,000 pet dogs, and came to the conclusion that breed may actually only be responsible for a small percentage of character traits.
“Breed offers little predictive value for individuals, explaining just nine percent of variation in behavior,” the authors wrote.