SALIVARY CORTISOL IN STALLIONS - THE RELATIONSHIP WITH PLASMA-LEVELS,DAYTIME PROFILE AND CHANGES IN RESPONSE TO SEMEN COLLECTION

The aim of this study was to investigate the usefulness of salivary co rtisol to monitor the hypothalamic-pituitary-adrenocortical axis activ ity in horses. Plasma and saliva samples were collected in 4 stallions at two hours intervals in one day. Saliva samples were collected in f ive stallions hourly during four days. Salivary cortisol was also moni tored in 15 min intervals one hour before and during two hours followi ng semen collection. Saliva collection is easily performed, non-invasi ve and non-stressful. Plasma and salivary cortisol were positively cor related (r(s)=0.83). Salivary cortisol showed a diurnal pattern with m aximum levels in the early morning and lowest in the afternoon (2.76 n mol vs. 1.73 nmol/l). Semen collection led to a significant increase i n salivary cortisol (p=0.019). The measurement of salivary hormones ma y be useful to assess the welfare of horses and offers an alternative way for a variety of clinical and endocrinological investigations.