Friday, November 6, 2009
There is a definite distinction between an animal yawning when he is tired and an animal yawning not through tiredness. Yawning in mammals increases the flow of oxygen to the brain and increases the heart-rate. All mammals can be seen yawning under nearly any circumstance, not just when they are tired or bored. In fact, because of the physiological impact of a yawn, some researchers believe that a yawn is used as a way to prepare the body for impending action. For example, many dogs that compete in agility competitions are seen yawning on the starting line, as if they are excited by the impending start and are giving their body an extra physiological boost prior to start. Similarly, a stressed dog can frequently yawn, as if they are maintaining readiness for unpredictable events - many dogs frequently yawn during obedience classes where they find the environment challenging and perhaps stressful.