Variations of serum cortisol in Argentine horses subjected to ship transport and adaptation stress

Abstract

The response to stress after transport by ship and adaptation to a new environment was evaluated by variations of serum cortisol (RIA method) in 40 horses imported in Italy from Argentina. The study started at arrival (April 2000) and lasted 6 months (October 2000). As a control group, 42 horses living in Italy have been evaluated. In all subjects, hematocrit, total protein, total bilirubin, urea, creatinine, and creatinine kinase were determined. In control horses, cortisol values ranged between 103 and 278 nM/L (mean 190.24 ± SE 13.50, SD 43.82, CV 23.03), and no significant differences among sex or age groups were observed ( P > .05). In subjects coming from Argentina, cortisol values observed at landing were within the normal range (193.73 nM/L ± SE 7.95, SD 50.29, CV 25.95), increased substantially in May (366.06 nM/L ± SE 10.25, SD 64.81, CV 17.70) and in June (337.19 nM/L ± SE 12.16, SD 76.89, CV 22.80) and returned to normal in October (187.87 nM/L ± SE 12.54, SD 43.50, CV 23.15). The differences observed in May and in June were significant in comparison with the values observed in April ( P < .01). The variations of CK in horses coming from Argentina were of great interest because they seemed at high levels in May and June. Data indicated that adaptation to the journey was very good. Stress conditions appeared in the first period of stay in Italy, maybe because of hierarchical conflicts resulting from an incorrect grouping of the subjects.