Cortisol and progesterone profiles in hair from birth to 90 days of age in foals.

Cortisol (C) and Progesterone (P4) are extremely important in equine gestation, parturition and newborn foal. The aim of this study was to investigate the profile of these hormones in foals hair from birth to 90 days of age. The study was carried out on 9 foals from the same farm, subjected to the same managerial factors. Each foal was submitted to four hair sampling, always from the same area, at 30 days intervals; samples were collected with clippers from the withers shaved to the level of the skin. All samples were analyzed by RIA. A significant trend of decreasing C levels was detected among sampling times: at birth hair cortisol concentrations (mean±SD) was 54.23±12.16 pg/mg; at 30 days of age 29.57±5.17 pg/mg (p<0.0001); at 60 days 18.41±2.01 pg/mg (p<0.0001); at 90 days 13.84±2.53 (p<0.001). This trend seems to suggest the progressive adaptation of foals during the first 3 months of growth. P4 levels, instead, remained rather constant from birth until 90 days of age: birth 556.31±79.18 pg/mg; 30 days 476.42±22.47 pg/mg; 60 days 490.83±30.94 pg/mg; 90 days 478.25±10.21 pg/mg. Will be extremely interesting to understand the meaning of these levels of P4 in pre-puberal animals.