bhmnscmmTIL yawning is observed in almost all vertebrate animals and is "contagious" across species. There is no consensus on why yawning occurs.
Flying SquidI used to have a dog that would yawn with a little whine whenever she was frustrated. It was adorable.
digitalgadgetThat's pretty common among cats and dogs. Sometimes the clever ones will hide a bite they decided against at the last second with a yawn, too.