Chronic stress – what does it do to the horse's body?

Chronic stress, the prolonged maintenance of tension, can cause all sorts of problems in horses. Stomach ulcers are a well-known problem with prolonged stress, but also weight loss, a lack of resistance, fertility problems and stereotypical behaviour (such as wind sucking) are related to chronic stress.

16 December '24 - 4 min reading time

Chronic stress occurs when a horse experiences continuous tension or fear. It is different from acute stress, where the horse is startled, possibly runs away or snores and then releases the tension. With chronic stress, the tension remains. For example, because the horse does not get enough roughage, has no social contact with other horses, or is trained at a level that is not suitable for him. But persistent pain, for example due to unrecognized lameness, can also lead to stress complaints in the long term. Chronic stress is not only a mental phenomenon, but mainly a hormonal event. The stress hormone cortisol in particular plays a role in this.

Immune system

Stress is actually nothing more than a state of readiness. The body is ready to tackle or escape threats. Stress can therefore have both positive and negative effects. In the case of short-term stress, the stress hormones ensure that the immune system is activated to ward off attacks. This is of course beneficial for the horse, if it is in an acutely threatening situation. But if the stress lasts longer, too much cortisol continues to circulate in the horse's body. This affects all kinds of biological systems. In fact, a kind of chain reaction is set in motion in the body, involving the brain, the adrenal glands, the pancreas and the liver. The blood sugar level can rise and the skeletal muscles can dump more waste products into the blood. The stomach can also develop problems. Stress also leads to a weakening of the immune system, making the body less resistant to diseases and infections.

Stress hormones

Stress hormones are released via a mechanism called the HPA axis. These are three hormone glands (hypothalamus, pituitary gland and adrenaline glands) that together produce hormones in a chain reaction during stress. Horses produce cortisol in particular via this HPA axis. Any form of stress, physical, emotional, from the environment or for example during feeding, can trigger the production of cortisol. Cortisol in the blood of horses is an indication of acute stress, cortisol in the saliva and manure indicates chronic stress. Although a short-term stress reaction is not bad and even essential for survival and adaptation in new situations, a continuously increased level of cortisol in the body is actually bad for your health. The heart rate can be permanently increased, as well as the breathing rate and body temperature. The amount of lactic acid in muscles can also be higher with more cortisol, which can cause poorer performance and muscle pain. In addition, there is a relationship between increased cortisol and stereotypical behavior such as wind sucking or weaving. Cortisol also plays an important role in inflammatory reactions and makes inflammation worse.

Coping strategies

Horses differ in the way they respond to stress. Just like with people, you can distinguish different 'coping strategies'. These are ways of dealing with stress and exciting situations. Research in wild groups of horses shows that there is a proactive strategy and a reactive one. A proactive horse will flee or fight. A reactive horse freezes when stressed and tense. It seems that the way in which the body of horses responds internally also differs between these two strategies. A proactive horse has a different physiological and hormonal response than a reactive horse. Proactive horses probably have a stronger response from the sympathetic nervous system, which increases their heart rate and blood pressure, for example. Horses that are reactive and freeze probably have higher activity in the HPA axis and therefore produce more cortisol. This could mean that these reactive horses are more sensitive to immune problems due to chronic stress. In any case, it is certain that the physiological response of horses differs. Not every horse is equally sensitive to chronic stress. And depending on their behavioral type, horses can experience different negative consequences from persistent stress in their lives.

Tackling chronic stress

Does your horse suffer from chronic stress? First of all, provide sufficient good roughage and free movement. Social interaction with other horses is also important to reduce stress. Also, provide variety in the work and give sufficient rest in between. Giving the mineral magnesium, preferably combined with B vitamins and the essential amino acid L-triptophan, can reduce anxiety and nervousness. In addition, to restore mental balance and support the immune system, an extract of cloves is very suitable. The clove plant contains powerful cannabinoids, which are signal substances that can help your horse to regain balance. Cloves stimulate the immune system and are anti-inflammatory and pain-relieving. In addition, herbal mixtures including triphala can be helpful in both acute and chronic stress.