Physiological and behavioral patterns of normal-term thoroughbred foals

Foaling is a crucial period in mares' life and their newborns, resulting in a number of physiological and behavioral challenges, which may have predictable effects on foal's welfare and well-being. The aim of this study was to assess the patterns of circulating adrenocorticotropic hormone (ACTH), cortisol, and glucose concentrations in newborn foals born by full-term delivery, by taking into account the potential correlations with Appearance, Pulse, Grimace, Activity, Respiration (APGAR) scores. Newborn respiratory rate, rectal temperature, birth weight, time to stand up, time to suck, and allantochorion weight were also considered. Eight thoroughbred foals, 5 colts and 3 fillies, were assessed 20 minutes (T0) and 30 days (T1) after birth. One-way analysis of variance showed a significant effect of time on ACTH (P = 0.0024) and cortisol (P = 0.003) concentrations, with the highest concentrations at T0. Significant positive correlations between ACTH and cortisol values at T0 (r = 0.67; P < 0.05) and T1 (r = 0.67; P < 0.05), and between cortisol and glucose at T0 (r = 0.55; P < 0.05), were observed. A positive and significant correlation between APGAR class and pregnancy length (r = 0.42; P < 0.05) was also recorded. All the functional parameters considered and foals' APGAR scores were within the physiological range. Our results indicate that the comparison between hormonal and metabolic data could be of major interest if correlated with APGAR score and functional parameters.