DOGS cry with joy when they see their owners after a short spell apart, scientists have found.
Pups well up when their favourite people get home because of a rush of “love hormone” oxytocin.
It starts when they see their owner after five to seven hours apart, such as following a school or work day.
The phenomenon applies even more with other people the dog has met before.
Scientists say it is the first time dogs’ emotional link on reuniting has been proven.
The experts arrived at their findings after measuring tears in 18 dogs.
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Tear levels then increased when oxytocin was dripped in the mutts’ eyes, linking the hormone to the emotional display.
In humans, oxytocin helps the brain build feelings of love, trust and affection.
The experts also found people show more emotion when shown photos of tearful dogs compared to dry-eyed hounds.
Professor Takefumi Kikusui, of Japan’s Azabu University, said: “We’d never heard of the discovery that animals shed tears in joyful situations, such as reuniting with owners.”
He said the finding was a “world first”.
Prof Miho Nagasawa said dogs were the only animals to have gained high level communication with humans using eye contact.
She added: “Their tears are thought to play a role in eliciting protective or nurturing behaviour from owners, resulting in a deepening of relationships and interspecies bonding.”
