Circulating beta-endorphin, adrenocorticotrophic hormone and cortisol levels of stallions before and after short road transport: stress effect of different distances.
BACKGROUND
Since transport evokes physiological adjustments that include endocrine responses, the objective of this study was to examine the responses of circulating beta-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 beta-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 beta-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 beta-endorphin, ACTH and cortisol levels.


CONCLUSIONS
The results obtained for short term transportation of stallions showed a very strong reaction of the adrenocortical system. The lack of response of beta-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.
Fazio
Esterina
E
Department of Morphology, Biochemistry, Physiology and Animal Production, Unit of Veterinary Physiology, Faculty of Veterinary Medicine, University of Messina, 98168 Messina, Italy. esterina.fazio@tin.it
Medica
Pietro
P
Aronica
Vincenzo
V
Grasso
Loredana
L
Ferlazzo
Adriana
A
D000324:Adrenocorticotropic Hormone / Q000097:blood; D000822:Animal Husbandry; D000818:Animals; D006736:Horses / Q000097:blood*; D006854:Hydrocortisone / Q000097:blood; D008297:Male; D013312:Stress, Physiological / Q000097:blood / Q000662:veterinary*; D014186:Transportation; D001615:beta-Endorphin / Q000097:blood
D001615:beta-Endorphin; D000324:Adrenocorticotropic Hormone; D006854:Hydrocortisone