Circulating β-endorphin, adrenocorticotrophic hormone and cortisol levels of stallions before and after short road transport: stress effect of different distances

Esterina Fazio¹ , Pietro Medica¹ , Vincenzo Aronica¹ , Loredana Grasso² and Adriana Ferlazzo¹

¹Department of Morphology, Biochemistry, Physiology and Animal Production, Unit of Veterinary Physiology, Faculty of Veterinary Medicine, University of Messina, 98168 Messina, Italy

²Unit of Clinical Biochemistry, University General Hospital (Gaetano Martino), University of Messina, 98168 Messina, Italy

author email corresponding author email

Acta Veterinaria Scandinavica 2008, 50:6doi:10.1186/1751-0147-50-6


Published:	3 March 2008

Abstract

Background

Since transport evokes physiological adjustments that include endocrine responses, the objective of this study was to examine the responses of circulating β-endorphin, adrenocorticotrophic hormone (ACTH) and cortisol levels to transport stress in stallions.

Methods

Forty-two healthy Thoroughbred and crossbred stallions were studied before and after road transport over distances of 100, 200 and 300 km. Blood samples were collected from the jugular vein: first in a single box immediately before loading (pre-samples), then immediately after transport and unloading on arrival at the breeding stations (post-samples).

Results

An increase in circulating β-endorphin levels after transport of 100 km (P < 0.01), compared to basal values was observed. Circulating ACTH levels showed significant increases after transport of 100 km (P < 0.001) and 200 km (P < 0.001). Circulating cortisol levels showed significant increases after road transport over distances of 100, 200 and 300 km (P < 0.001). An effect of transport on β-endorphin, ACTH and cortisol variations was therefore evident for the different distances studied. No significant differences (P > 0.05) between horses of different ages and different breeds were observed for β-endorphin, ACTH and cortisol levels.

Conclusion

The results obtained for short term transportation of stallions showed a very strong reaction of the adrenocortical system. The lack of response of β-endorphin after transport of 200–300 km and of ACTH after transport of 300 km seems to suggest a soothing effect of negative feedback of ACTH and cortisol levels.