Researchers in Japan have found that dogs might be like humans more than people realize.
A study published Monday in the journal Current Biology suggests that the eyes of man's best friend might fill up with happy tears when they reunite with their owner after being away from them.
In a press release, the scientists said they conducted the Schirmer tear test on 22 dogs for their experiment, allowing them to compare a dog's tear volume before and after being away from its owner or someone they knew for five to seven hours.
They placed a piece of paper under the dog's eyes to gather the tears, then they measured them, the study said.
Researchers found that when reunited with their owner, the dogs' tear volume increased significantly than when they were reunited with a familiar non-owner.
According to the study, researchers also found that if a solution of oxytocin - a hormone associated with love - is added to the animal's eyes, the tear volume increases.
"We found that dogs shed tears associated with positive emotions," the study's co-author Takefumi Kikusui said in a statement.
According to Kikusui, this type of study is a possible "world first.".