In addition, there is a difference between short-term stress and prolonged stress. In general, we can say that being startled once is not a problem, but prolonged exposure to stressors is. When stress becomes chronic, it can lead to continuously elevated cortisol levels in the blood, which can cause physical damage. Long-term stress can also lead to issues such as stomach ulcers, unmanageable behavior, weight loss, stiff muscles, and depression in your horse.

Physical Stress / Training Stress

Physical stress results from bodily strain, such as intense training, injuries, or illness. Not all physical stress is bad. Training, for example, always causes a certain level of stress in the muscles. If rest follows, the muscles recover at a higher level. This is called the "training effect"—and it can’t exist without some physical stress. Symptoms of physical stress can range from increased respiratory rate and sweating to muscle soreness and fatigue. If your horse is frequently sore, tired, or not progressing in training, the physical stress is probably too high. Training that is too intense or too long without enough recovery can lead to overexertion and stress. Symptoms may include fatigue, injuries, or reduced performance.

Emotional and Social Stress

Emotional stress can be triggered by fear or restlessness, for example due to changes in the environment, new horses in the group, or unfamiliar sounds. It can also arise when a horse does not feel secure in its herd—due to isolation or dominance fights—or doesn’t understand its handler. In general, emotional stress arises when a horse cannot be itself. This is also related to management. Horses may respond to emotional stress with behavioral changes such as kicking, biting, or restlessness. They may also shut down or stop responding to stimuli or aids, which are further signs of emotional stress.

Environmental Stress

Changes in the environment—such as moving to a new stable, transport, or changes in pasture—can also cause stress. Horses may react with restlessness or a reduced appetite. This type of stress usually resolves on its own, but sometimes horses need support during environmental changes. A course of herbal extract can be very helpful. Herbs like chamomile, chasteberry, and passionflower are suitable. A liquid extract is preferable, as it is more easily absorbed by horses.

Nutritional Stress

Horses need (almost) unlimited access to roughage, as their digestive system is designed for this. Unlike humans, a horse’s stomach produces stomach acid continuously—not just during meals. This means the stomach can become too acidic if the horse goes too long without roughage, which can lead to stomach ulcers and pain. Nutritional imbalances—such as deficiencies or sudden changes in diet—can also cause stress, leading to digestive issues or behavioral changes. In addition to sufficient, high-quality roughage, horses also need supplementation with vitamins and minerals.

Is Stress Always Bad?

Stress—no matter the cause—is not always a bad thing! In fact, stress can’t be completely avoided. As a flight animal, a horse can easily experience short-term stress. It only becomes a problem when the stress lasts too long or becomes chronic. That’s when physiological disorders and behavioral issues can develop. It’s therefore important to recognize signs of stress in horses early. This allows you to decide whether to intervene and how. That way, you keep your horse healthy and happy.