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Palme, R. (2015). Non-invasive monitoring of stress hormones for welfare assessment in domestic and wild equids. In K. Krueger (Ed.), Proceedings of the 3. International Equine Science Meeting. Proc. 3. Int. Equine. Sci. Mtg, in prep. Wald: Xenophon Publishing.
Abstract: Stress responses play an important role in allowing animals to cope with challenges. Glucocorticoids, key elements in the neuroendocrine stress axis, are traditionally measured as a parameter for welfare assessment. As blood sample collection itself disturbs an animal, non-invasive or minimal invasive methods have gained importance for assessing stress. In horses saliva and faeces are most frequently used. Faecal samples offer the advantage that they can be collected easily and stress-free. In faecal samples circulating hormone levels are integrated over a certain period of time. As a consequence faecal glucocorticoid metabolites represent the cumulative secretion and they are less affected by short episodic fluctuations of hormone secretion.
However, in order to gain reliable information about an animal’s adrenocortical activity, certain criteria have to be met: Depending whether the impact of acute or chronic stressors is assessed, frequent sampling might be necessary whereas in other cases, single samples will suffice. Background knowledge regarding the metabolism and excretion of glucocorticoids is essential and a careful validation is obligatory. In addition, this presentation will address analytical issues regarding sample storage, extraction procedures, and immunoassays and various examples of a successful application in equids will be given. Applied properly, non-invasive techniques to monitor stress hormones are a useful tool for animal welfare assessment.
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Aurich, J., Wulf, M., Ille, N., Erber, R., von Lewinski, M., Palme, R., et al. (2015). Effects of season, age, sex and housing on salivary cortisol concentrations in horses. Domest. Anim. Endocrinol., .
Abstract: Abstract Analysis of salivary cortisol is increasingly used to assess stress responses in horses. Since spontaneous or experimentally induced increases in cortisol concentrations are often relatively small for stress studies proper controls are needed. This requires an understanding of factors affecting salivary cortisol over longer times. In this study, we have analysed salivary cortisol concentration over 6 mo in horses (n = 94) differing in age, sex, reproductive state and housing. Salivary cortisol followed a diurnal rhythm with highest concentrations in the morning and a decrease throughout the day (P < 0.001). This rhythm was disrupted in individual groups on individual days; however, alterations remained within the range of diurnal changes. Comparison between months showed highest cortisol concentrations in December (P < 0.001). Cortisol concentrations increased in breeding stallions during the breeding season (P < 0.001). No differences in salivary cortisol concentrations between non-pregnant mares with and without a corpus luteum existed. In stallions, mean daily salivary cortisol and plasma testosterone concentration were weakly correlated (r = 0.251, P < 0.01). No differences in salivary cortisol between female and male young horses and no consistent differences between horses of different age existed. Group housing and individual stabling did not affect salivary cortisol. In conclusion, salivary cortisol concentrations in horses follow a diurnal rhythm and are increased in active breeding sires. Time of the day and reproductive state of the horses are thus important for experiments that include analysis of cortisol in saliva.
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