It turns out that yawning in horses has puzzled several people as there are many postings on the topic. Physiologically (in both horses and humans), yawning is associated with a variety of neurochemical substances that are secreted in the brain in association with changes in state of arousal.
- Both people and horses tend to yawn when there is a change in the state of arousal. Unsurprisingly, this frequently happens when waking up from a period of drowsiness, but it also can happen after a sudden fright or after something pleasurable.
- Since horses also yawn after massages or chiropractic treatments, some people believe that it indicates a release from tension or stress.
- Yawning can also occur after the horse has been holding its breath, often from being stressed physically or mentally. The yawn is an attempt to refill its lungs. Monty Roberts concurs that "the act of yawning is to take in oxygen. One element of tiring is starving the brain of oxygen. During exertion and tension we assign oxygen to muscles needed for work. Horses in their quest for survival will enter periods of extreme concern and rob the brain severely. They'll push themselves for a long time and then when they become satisfied that they are not going to die, they'll relax and yawn because their system is taking over to re-oxygenate the brain.
- Someone read that its a way that horses clear dust from their airways.
- Several people reported that their horses yawn in between taking their halters off and putting their bridles on, speculating that the horse likes to stretch its jaw before the restriction of the caveson.
- Some people believe it's just a habit.
Yawning can also be a sign of medical problems, although it's less frequent.
- It can be a sign of abdominal pain or colic, or to relieve the pain from ulcers
- Yawning can also be a neurological symptom of liver disease (as ammonia builds up in the blood it crosses the barrier to the brain which results in neurological symptoms one of which is yawning).
Who would have thought that yawning could mean so many things! The good news is that most of the time, it is harmless.
