Skip to main content

Science says dogs cry tears of happiness when reunited with their humans

New study shows dogs cry happy tears when reunited with pet parents

A man hugs a Golden Retriever, facing away from the camera
Eric Ward / Unsplash

There are so many ways to tell whether a dog is happy. We all know to look for a wagging tail, but there are countless clues hidden in a dog’s body language to let you know how they feel. But for the first time ever, Japanese researchers have confirmed that dogs show emotion in another way: by crying.

While the image of a crying dog can be enough to bring a person to tears themselves, empathetic people can rest assured–there are no sad dogs here. In fact, scientists recently discovered that dogs cry happy tears when reunited with their pet parents. Now that is a sign of true love!

A woman hugs her small, brown dog and laughs as the dog sniffs her face
Tamas Pap / Unsplash

Scientists wanted to explore whether tear reactions are similar in dogs and people

Azabu University professor Takefumi Kikusui was first inspired to discover the role of tear production in dogs while watching one of his Standard Poodles nursing her puppies. He noticed that she appeared to tear up while nursing, and the professor hypothesized that dogs can experience happy tears, too. After a bit of research, this pet parent and the professor found zero studies focusing on emotional tear production in animals.

Recommended Videos

The study he co-authored was published in Current Biology and shows that dogs do indeed experience emotional tear production. In fact, researchers “measured tear volume in dogs before and after reunions with owners and familiar non-owners” to test their theory. They found that dogs’ tear production increased after a reunion with a pet parent, but not after a reunion with a familiar person who wasn’t their owner.

As a confirmation, researchers studied whether or not canine tear volume increased with the introduction of oxytocin, a ‘feel-good’ chemical that the brain secretes. It did! This suggests that this emotional hormone plays a role in the ‘crying dog’ phenomenon.

a man dressed in a Jacket holds his black and brown dog in his arms and kisses the dog
Chewy / Unsplash

Tear production may help increase emotional bonds between dogs and humans

Tears have several purposes, including washing away debris in the eye. They can also be a physical manifestation of strong emotion and a tool for people to understand one another’s feelings. As Takefumi Kikusui and his colleagues uncovered, though, tears may also play a role in the human-animal connection.

The last phase of the study included a test in which people were asked to rate their impressions of pictures of dogs. Participants rated pictures of dogs both with and without artificial tears in their eyes, and they actually had a more positive impression of the dogs with tears. This could be because people relate more to an animal if they can physically see a sign of emotion. How fascinating!

Kikusui has come to the conclusion that the bond between people and pets might be even stronger than originally believed, especially since he has seen evidence of emotional response in dogs. Still, it’s easy to understand why some folks are surprised to learn that dogs’ emotions and humans’ emotions might show themselves similarly. People can’t wag a tail when happy and prefer not to sniff behinds out of curiosity, but our two species may not be as different as we think.

Gabrielle LaFrank
Gabrielle LaFrank has written for sites such as Psych2Go, Elite Daily, and, currently, PawTracks. When she's not writing, you…
6 ways to soothe your dog’s separation anxiety for good
Will your dog grow out of it on their own? We'll cover the facts
A small dog lies on a green welcome mat with someone's feet nearby

As difficult as it can be to be away from your pet, separation anxiety in dogs can make it even trickier. Between your pup’s inappropriate, destructive behavior and his clear distress, it’s completely understandable why you may dread leaving the house. Fortunately, you can learn how to ease separation anxiety in pets by keeping an eye on their demeanor and doing some research of your own.
It’s important to remember that nothing will change overnight. Anxiety is a fear-based psychological issue that should be attended to with as much patience and understanding as possible. Taking a gentle approach will help your dog stay confident and trusting throughout this journey with you. Don’t know where to start? Here are some ideas for dog separation anxiety help.

Rule out medical issues

Read more
Why do dogs like squeaky toys? The reasons are sweet and instinctual
The science and psychology behind dogs' love for squeakers
A brown and white border collie carrying a stuffed toy caterpillar in its mouth

If you have a particularly playful dog at home, it's not unusual to spend nearly as much money buying squeaky toys as you do on your dog's food. Destructive dogs have a knack for de-stuffing and de-squeaking toys in record-setting time, but it's still worth it when you're cleaning up shredded toys instead of your new shoes.
But why do dogs like squeaky toys so much? There's something about the high-pitched sound that gets most dogs worked up, but there's no denying that some pups are downright obsessed. Here's what you'll want to know.

Squeaky toys allow your dog to indulge their natural hunting instincts

Read more
Why do dogs eat dirt? There may be a huge health issue, experts say
It could be medical or behavioral — here's how to tell
Dog eating dirt

If your dog frequently comes in from the outdoors with a dirty mouth, don’t take it lightly. He could be consuming dirt, and that can lead to health problems, according to experts at UC Davis School of Veterinary Medicine. Dogs who develop unusual eating habits where they persistently chew and consume nonfood-related items, including dirt, suffer from a disorder known as pica.

But why do dogs eat dirt? Experts say that this eating disorder can be a symptom of an underlying medical problem, stem from behavioral issues, or simply be that a dog is attracted to the smell and taste of the soil. If your dog is a compulsive dirt eater, you should discuss the problem with a veterinarian to rule out any serious health issues.
Medical reasons why dogs eat dirt

Read more