By Kerri Fivecoat-Campbell
Studies have shown that people yawn between 5-15 times per day. Sometimes we find ourselves yawning when we’re tired, as a way to release ear pressure, or when we see someone else yawning.
However, years of studies on yawning have yet to conclusively prove why we yawn.
Humans are not the only species that yawn—yawning can be found in a variety of animals including birds, monkeys, cats, and yes, dogs.
Why do dogs yawn? We asked some experts to weigh in on this common dog behavior.
What is a Yawn?
Wayne Hunthausen, DVM at Westwood Animal Hospital in Westwood, Kan., who is also a animal behavioral consultant and author of “The Behavior Problems of the Dog and Cat,” defines a yawn as “extending the jaw with a rapid intake of air that expands the lungs that sometimes is accompanied by vocalization.”
In humans, it has long been thought that yawning is a sign of boredom. “We used to believe that the purpose of a yawn was to gulp down air to wake up a fuzzy brain,” says Stanley Coren, professor emeritus in the department of psychology at the University of British Columbia in Vancouver and author of the book, “Do Dogs Dream?”
Other early studies may have pointed that yawning is a physiological response to being in a warm room and that yawning may cool down the brain, said Hunthausen. “The study effectively found that people yawned less in cooler environments,” he said.
However, he said, modern studies have researchers believing that yawning in both humans and animals may be a sign they are tired—for example, your dog may yawn when he wakes up - but it is often more of a psychological and communicative sign.
Dog Yawning: A Sign of Stress?
Ask any dog trainer and they will tell you that the reason a dog yawns is to communicate that he is in a stressful situation. “I see dogs yawn everyday in stressful situations,” says Sean Savage, a certified professional dog trainer and behavior consultant in Kansas City, Mo. “Dogs in obedience scenarios that are not responding well to training yawn. I’ve also seen dogs that need to go outside yawn as a way to communicate,” he says.
Coren explains that dog yawns are not only signals to humans of stress, but can be a form of communication between dogs as well. “There have been studies that show that sometimes a passive dog will yawn in response to an aggressive dog, which causes the aggressive dog to break off the interaction,” says Coren.
Is Yawning Contagious Between Dogs and Your Dog and You?
Contagious yawning between humans is well documented, but can dogs “catch” the yawns from other dogs or from their humans?
A 2014 study published in Animal Cognition did conclude that shelter dogs that had a rise in salivary cortisol levels, which is a sign of stress, caught contagious yawns more often than those dogs that didn’t have a rise in salivary cortisol levels. This suggests that stress yawns among dogs might be contagious. [i]
Several studies have concluded that yawns are contagious between humans and dogs. One of the most famous studies, which was conducted by researchers at Tokyo and Kyoto universities and published in U.S. science journal PLOS One in 2013, concluded that “contagious yawning” was a sign of empathy dogs were showing their humans and not a sign of stress.
The researchers studied two-dozen dogs and involved humans both familiar and unfamiliar to the dogs. The people involved in the study also made different facial expressions and mouth gestures to determine if dogs could tell the difference.
Researchers also monitored the dog’s heart rate to rule out yawning as a stress response. The results revealed that dogs yawned contagious yawns more often with familiar humans. "Our study suggests that contagious yawning in dogs is emotionally connected in a way similar to humans," says Teresa Romero of the University of Tokyo who led the study.[ii]
Georgina Lees-Smith, a certified canine behavior consultant near London in the U.K., who has studied and written about the varying theories about dog yawning for her post graduate degree in psychology and neuroscience, says that her own anecdotal research seems to support that theory.
“I’ve conducted a study with my own dogs and have found that if you yawn and your dog yawns, it shows a definite social connection with your dog,” she says. “It really is quite lovely.”
The Dog Yawning Conclusion
While we cannot be absolutely sure why dogs yawn when they are not tired, modern studies have suggested that dogs yawn for several reasons, based on the circumstances:
- Dogs may yawn as a response to stress
- As a communication signal toward other dogs
- In empathy (or at least in response to) their humans