Stress is a broad term and can be defined in simple terms as the activation of the sympathetic nervous system and the hypothalamic-pituitary-adrenal axis by a trigger (stressor) and all associated processes in the organism.
Depending on how strong the effect of this stressor is, the organism can counteract it accordingly. Important messenger substances that are released during a stress response are, for example, catecholamines and cortisol. However, the quantification of these messenger substances only allows a less than satisfactory assessment of the stress experienced, as gender, age, race and time of day have an influence on their release. In addition, they are released in every type of state of arousal, i.e. both in the case of a positive expectation and in the case of a negative expectation. It has therefore been shown that the determination of cortisol primarily allows the state of arousal and the response to acute stress to be determined.
Newer biomarkers, some of which can be determined non-invasively, appear to be more suitable for quantifying prolonged negative stress (distress). In this context, the interaction between a stress response and the immune system is of particular interest. The function of the immune system is strongly negatively influenced by prolonged negative stress.

Aim of the study

In our project, we want to concentrate on biomarkers that can reflect the influence of chronic stress on the immune system.
The focus of the current research project is on the establishment and validation of stress markers in horses. Echocardiography and ECG (at rest and during exercise) are usually performed to assess the severity of heart valve disease
. Furthermore, it would also be relevant to determine how much stress the findings on the heart cause on the body. In other words, how much stress is caused by the disease. This is precisely the question at the centre of our study.