TDK conference 2018

Due to the intensive management, the growing number of races and competitions and long traveling times, horses are nowadays increasingly exposed to stress. Different types of stress may result in poor performance or may lead to pathological processes (so called adaptation diseases) such as gastric ulcer. The ability to overcome stress in horses depends on many things. To assess the stress level and stress burden of animals, it would be of great help to establish a test protocol that would be applicable in practice. Earlier studies have applied several methods to detect stress but a protocol that works reliably under most circumstances, and easy to perform is yet to be established.

The cortisol level often serves as a basis of stress research, both in domestic and wild animals. The presence of stress can be detected indirectly with the help of the seral concentration of cortisol. In a stressful situation both blood cortisol and its stimulant ACTH (adrenal cortex stimulating hormone) levels are proven to rise due to the activation of the HPA axis (hypothalamic-pituitary-adrenal cortex).

Our aim was to establish the most appropriate sampling times and methods and cortisol measurement technique, while taking into account some of the most common factors that affect serum cortisol levels and detection.

Six healthy horses were tested at the same time under the same conditions. On day zero, after taking the signalment and basic clinical data of the animals, we have completed a temperament questionnaire and inserted a vein cannula. The studies were carried out in the next 4 consecutive days exactly in the same timely manner: on day one a basic cortisol curve was set up, on the second day ACTH was injected to evaluate HPA axis activity, on the third day a feed withdrawal stress test was performed, on the 4th day the repeatability of the tests was verified. As a final step of the process, the blood samples (216 samples in total) were measured by a commercial ELISA test (Enzyme-linked Immunosorbent assay) as the most convenient cortisol detection tool in the everyday practice.

In our study the ELISA test proved to be a reliable technique to measure serum cortisol levels.. Compared to previous cortisol measurement studies in the literature, we have obtained similar results in most aspects and we have set up a reliable test protocol.