Telltale Signs of Stress in Horses
that the horse might be feeling stressed, and by yawning, it is releasing this stress.
Tooth Grinding
Some horses grind their teeth while stabled, some while ridden. Tooth grinding can be a sign of physical or physiological stress. If the horse has no other dental issues, it's important to check for things like equine gastric ulcer syndrome (EGUS) and other sources of chronic pain or stressful situations
Bad Behavior
Many examples of poor behavior while being ridden, can be caused by physiological or physical stress.3 Stress can be expressed through pawing, pulling, tail wringing, bucking, rearing, bolting, or being cold backed (sensitive in the back).
EGUS
Many performance horses suffer from equine gastric ulcer syndrome.6 This can be in response to a stressful show schedule or other stressors.
Manure and Urination
A horse that is stressed can produce copious amounts of manure within a short time. Some may produce very runny manure. Horses will often urinate if stressed, and if they can't relieve themselves because they can't relax, such as in a trailer or when being ridden, they can become antsier.
Licking and Chewing
Natural horsemanship concepts suggest that licking and chewing is a sign that a horse is accepting new information, such as during training. As long as this behavior is not abnormally repetitive or compulsive, this action may be more like yawning in its function, as a way to release any stress the horse may be feeling.
Colic
Colic symptoms may be caused by stress. A new herd mate or changes in routine, weather, or handler can be enough to make some horses mildly colicky. Chronic stress can lead to EGUS, which can cause colic symptoms.7