When it comes to contagious yawns, a new study suggests dogs are no more immune than humans.
The Japanese study of 25 dogs found that pups, like humans, tend to yawn after seeing someone else yawn - especially if that someone is their owner. But the yawns have to be genuine, with only a Lab, a Maltese, a Chihuahua and two mixed breeds reacting to fake yawns.
"Our study suggests that contagious yawning in dogs is emotionally connected in a way similar to humans," study author Teresa Romero at the University of Tokyo said in a statement.
The study was published today in the journal PLoS One.
To rule out the possibility that the dog yawns are part of a distress response to seeing strained human faces, the researchers measured the animals' heart rates and found no increase during real or fake human yawns.
"Although our study cannot determine the exact underlying mechanism operative in dogs, the subjects' physiological measures taken during the study allowed us to counter the alternative hypothesis of yawning as a distress response," Romero said.
Other fun, furry findings: A male Siberian husky and a female German shepherd mix yawned the most during the study, with five and six yawns apiece; and the oldest dog - an 11-year-old miniature poodle - yawned only twice. Fourteen of the dogs failed to yawn at all.
But not all humans are prone to contagious yawning either. Only 45 to 60 percent of healthy adults experience the phenomenon, according to the new study. And while some research suggests it's a form of release, other studies find it plays a role in communication and empathy.
So next time you and your pooch get a case of the yawns, consider it a testament to your friendship.