Cortisol concentration in the saliva of horses subjected to different kinds of exercise

Katarzyna Strzelec,Sławomir Pietrzak,Marta Kankofer

doi:10.2754/avb201180010101

Katarzyna Strzelec, Sławomir Pietrzak + Show 1 more

Open Access

https://doi.org/10.2754/avb201180010101

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Abstract

The aim of this study was to characterize the stress level in sport horses subjected to exercise by measuring the cortisol concentration in their saliva. The experiment was conducted on 5 groups of horses (49 animals): one control and four groups undergoing different types of exercises. The saliva samples were collected 3 × a day: late at night (between 20:00 and 23:00 h), early in the morning (between 5:00 and 8:00 h) and directly after the exercise. The concentration of cortisol was measured by the enzyme-immunoassay programme. The highest cortisol concentration was observed for the horses participating in 3-day events (8.93 nmol/dm3), whereas in the control group it was only 0.28 nmol/dm3. When compared to the cortisol concentration of other horse groups, this suggests that the stress level as measured by the cortisol concentration in saliva increases with increasing exercise intensity and its duration. The obtained results do not confirm the existence of a day rhythm of the cortisol concentration in horses. Moreover, the results may help in choosing the appropriate system of training and in improving horse welfare during competitions.

Highlights

Stress is related to biochemical reactions leading to the formation of substances that are commonly described as indicators of the stress level
One of the main substances that indicate stress level is cortisol which is a natural glucocorticoid hormone produced by the adrenal cortex
The concentration of cortisol depends on the natural circadian rhythm, which can be disturbed by physical as well as mental stress

Summary

Introduction

Stress is related to biochemical reactions leading to the formation of substances that are commonly described as indicators of the stress level. The determination of cortisol concentration in animal serum is not always possible and taking blood samples causes additional stress. For this reason, easier and less invasive methods have been invented that make use of saliva, urine and faeces. The most effective way of determining cortisol concentration in animals seems to be by using their saliva This is because taking saliva samples is a rather simple, non-invasive and low-stress procedure (Aardal and Holm 1995). The rate of balancing the cortisol concentration in saliva and blood is rapid: the whole process takes less than 5 min For these reasons, determining the level of cortisol using saliva is a more advantageous way of examining the adrenal cortex functions than using blood serum (Vining et al 1983). We need a relationship between such different stress intensities and the cortisol concentration in horse saliva

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