Transport-related stress in five-day-old foals and their dams

Abstract

Horses are frequently transported by road but little is known about the stress response of transported newborn foals. In this study, we have analyzed the stress response of postpartum Haflinger mares (n = 6 over two years) and their 5-day-old foals (n = 12) to a 20 km road transport in a trailer with the middle partition either removed or separating the mare and her foal. Noninvasive techniques were used to analyze the physiological stress variables such as salivary cortisol, heart rate, and heart rate variability (HRV). Mares and their foals responded to transport with an increase in cortisol concentration (P < 0.001). The increase was more pronounced and prolonged in foals compared to their mothers (P = 0.001). Heart rate increased in mares and foals during transport (P < 0.001) but this increase was less pronounced in foals compared to mares (P = 0.001). The HRV increased during transport (P < 0.05) in mares but remained constant in transported foals. The presence or absence of the partition was largely without effect on the physiological stress variables determined. In conclusion, 5-day-old foals respond to road transport with a clear adrenocortical activation which was more pronounced than in their dams. There were no changes of HRV in transported foals.