There is a saying  English that says a dog is a man's (and woman's) best friend. Dogs and humans have shared close and loving relationships  thousands of years. Scientists believe the bond between humans and dogs is deeper than we thought. The scientists discovered that dogs cry tears  joy when they see their owners after a period  absence. The scientists conducted a small-scale study  22 dogs. They tested the behaviour  the dogs.  particular, they looked  how the dogs reacted when they were reunited  their owners and with other people they had daily contact . The scientists said that when the dogs saw their owners, they cried.
The researchers,  Azabu University and Jichi Medical University, put strips  paper under the dogs' eyes. They then checked to see if, and when, the dogs cried. The scientists found that when the humans and dogs were reunited  five to seven hours  separation, the dogs shed tears. Researcher Takefumi Kikusui said: "We had never heard  the discovery that animals shed tears  joyful situations, such as reuniting with their owners." He added: "Their tears might play a role  the deepening  mutual relationships." He believes the tears may make humans love their dogs more. He said: "It's possible that dogs who show teary eyes  human interaction would be cared  more."