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When humans are reunited with their pets, owners might shed more than a few tears. But do dogs do the same? Until now, most evidence has indicated that, while they do exhibit empathic responses to humans in need of comfort, dogs do not cry. But a new study from Japan, published in the journal Current Biology, suggests that our canine companions might actually well up, too, when reunited with their owners. 

It’s no secret that dogs have close emotional bonds with their owners, demonstrating keen social intelligence and displaying human-like emotions. When pets reunite with owners from whom they have been separated for a period of time, they display “affiliative behavior.” These are actions that another organism finds satisfying or as agreeable behavior that helps create social connection between two parties.  

In the case of dogs reunited with their owners, the pups exhibited affiliative behavior like licking human faces, jumping on their owners, and wagging their tails. During these times, they experience the release of oxytocin, the so-called “love hormone,” as other studies have shown. 

Determining If Dogs Shed Tears

In this study, the scientists proposed that dogs would emit tears during owner reunions because of oxytocin; in response, owners would want to comfort the animals in turn. Researchers initially asked people to rate how much they wanted to care for a dog based on photos where dogs featured had either no tears or artificial tears. People ranked the pictures of dogs. Those with artificial tears ranked higher than those without artificial tears, meaning that people desired to care for dogs with tears in their eyes. In real life, such a reaction could reinforce an existing human-canine bond.   

Pug laying down indoors looking sad.
claudiodoenitzperez/Getty Images Plus via Getty Images

From there, researchers selected 18 dogs without separation anxiety or health issues, ones that had owners with good handling experience. Scientists measured these dogs’ daily tear production. They captured the volume of dogs’ tears when the dogs were home or spending time together with their owners versus when they were reunited with their owners after being home alone for five to seven hours. It was found that dogs teared up significantly more when they got back together with their owners after a time apart than when they were home with their owners. 

However, it’s important to note that no mention was made of the dogs’ breeds and how that might have impacted the study. For example, Shih Tzus have more prominent eyeballs, which could potentially skew the results. While some female dogs were spayed, all male dogs involved in the study were neutered, notes Dr. Jerry Klein, DVM and AKC’s Chief Veterinary Officer. While both male and female mammals secrete oxytocin in stressful situations, females produce more than males, which could also have skewed results. 

A similar test was performed with 20 dogs at a daycare facility. Tears were measured after the owners left as well, as well as when the owners returned. Dogs were separated from and then reunited with a familiar figure and with their owners; results showed that dogs emitted more tears when reunited with owners than familiar non-owners. In addition, some dogs were dropped off at daycare, then their tear secretion was measured once they were given either a control substance or oxytocin. Dogs who received oxytocin secreted more tears than those with the control substance.   

Pembroke Welsh Corgi puppy laying on a black leather cushion.
Nadeika/Getty Images Plus

Do Dogs Cry from Emotion?  

Dogs crying for emotional reasons may be be more in our minds than not. “Apart from the hormone oxytocin, one probable reason that humans respond to a dog’s tears is the behavioral principle of generalization,” says Dr. Mary Burch, Ph.D., a certified applied animal behaviorist and director of the AKC’s Family Dog Program. “We have a tendency to pair tears with the crying of someone (either a person or animal) who is in pain, sad, or in an emotional state where they need our caring and support. We know how we feel when we cry, and we connect in an emotional and sympathetic way with dogs who are tearful. 

It’s clearly possible that dogs exhibit tears to elicit caregiving behaviors from humans. Contact is clearly super-important in establishing relationships for canines and humans alike. As dogs and humans developed alongside one another, perhaps they did indeed begin emitting tears to ensure they’d be taken care of to further the human-canine bond. Or at least we can hope our dogs miss us that much when we’re gone. 

Related article: Do Dogs Grieve the Loss of Their Human Owners?
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