Your dog might have jumped out the door and licked you when you came home from vacation. Also, that's not the only thing.

A new study published in the science journal Current Biology claims that your dog's eyes could be made wet by the emotions gushing inside.

The love hormone is thought to drive this tear production. Dogs and mammals release oxytocin while bonding with their babies. The lead author noticed that his poodle's eyes became watery when it nursed its puppies.

I thought that it might increase tears. Kikusui is a veterinary medicine professor at Azabu University in Japan.

In order to perform the test veterinarians folded a strip into the dog's lower eyelid and held it there for a short time. The strip measures tears that are already there, tears that are produced because of the strip itself, and tears that are not caused by the irritation of the eye.

The researchers included people who the dogs were familiar with, but not their owners, in order to make sure that the dogs produced tears because of their owners. When the dogs met their owners the tear volume went up more than when they met their acquaintances. The researchers found that the tear levels went up even more when they applied the solution to the dogs' eyes.

"I think this is potentially a groundbreaking experiment, simple and clever."

Miiamaaria Kujala is a cognitive neuroscience professor at the University of Helsinki. The study did not involve Kujala.

She explained that dogs and other animals don't cry a lot, so nobody had conducted this kind of experiment before. The scientific community will have to repeat this experiment in the future to confirm this finding.

The study found that the dogs' eyes made people care more. The researchers wanted to know how much people wanted to care for the dogs. The dogs with tears were ranked higher than the ones without tears.

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Dog tears could be used as a means of stoking human care. Producing tears might be a way to communicate. Humans can produce tears. Pheromones are chemical signals that animals use to communicate.

The area of dog cognitive research is still in its early stages. There are many theories as to why dogs grow so close to humans. Dogs were one of the first domesticated animals. The development of agriculture has been affected by our friendship with dogs.