Researchers at the University of Porto in Portugal also found that dogs yawn even when they only hear the sound of their owners doing the same.
"Unexpectedly, results showed an interesting interplay between contagion and social effects. Not only were dogs found to catch human yawns, but they were also found to yawn more at familiar than unfamiliar yawns," study author Karine Silva was quoted as saying by LiveScience.
Past research has linked contagious yawning to empathy -- the ability to understand and interpret another's emotions -- in humans. They have shown that people who perform better on empathy-related tasks also contagiously yawned more.
A link has also been seen in baboons -- they catch yawns best from baboons they are closest with. A 2008 research had also indicated that most dogs catch yawns from their owners as well, but other studies questioned this finding.
In the new study, published in journal Animal Cognition, Silva and team played several sounds to 29 pet dogs to see their reactions: their owner's natural yawns, a natural yawn from another human, and, as a control, these yawns played backward, which doesn't trigger contagious yawning in animals.
They played the sounds back to the dogs consecutively for five times, followed by five seconds of silence. They cycled randomly through the four types of sounds in two sessions, separated by seven days.
Only 40 per cent of the dogs tested ended up yawning during the experiment. Eight of the dogs yawned while the human yawning sounds were being played, and one yawned during control sounds. These dog yawns came significantly more often when they were listening to their owner's yawn.
"Although not allowing for conclusive inferences about the mechanisms underlying contagious yawning in dogs,the study provides first data that renders plausible empathy-based, emotionally connected, contagious yawning in these animals," the researchers said.
"If it emerges that it is, then giving the growing range of roles being played by dogs in human society (as service and therapy dogs, for example), it could turn out a useful complementary tool for selecting the most appropriate dogs (in terms of empathic processing) for specific tasks," they added.
