Dogs get tears of joy when reunited with owners, study finds
PHILADELPHIA (CNN) -- Man's best friend may be more like man than we realized. New research from Japanese scientists suggests a dog's eyes may well up with tears of happiness when reunited with its owner after an absence.
Dogs, like humans, have tear ducts that produce tears to keep their eyes clean and healthy, but tears in dogs hadn't been linked with emotion before this study.
To investigate the link, researchers measured the amount of tears among 18 dogs with a standard test.
It involved a paper strip placed inside the eyelids of the dogs for a minute before and after they were reunited with their owners after five to seven hours of separation.
They did the same test when dogs were reintroduced to people they knew, but the amount of tears only increased during reunions with their owners.
The study was published Monday in the journal Current Biology.