Oestrogens in faeces as an indicator of the foeto-placental unit function in mares

Abstract

Total of 30 pregnant mares were used in this study: 17 Thoroughbred and 13 Primitive Polish Horse. The concentration of total unconjugated oestrogens was determined by radioimmunoassay in faecal samples obtained every second week after mating until delivery or interruption of pregnancy. Concentration of oestrogens in pregnant healthy mares ranged from 40 to 200 ng/g and showed typical profiles for pregnancy. In 5 of 30 mares (16.6%) of either breed abortions and cases of embryonic death occurred. Abortions were preceded by sharp or gradual decrease in oestrogen concentration, whereas prior to embryonic death no elevation of the level of these hormones was noted. The present data suggest that determination of faecal oestrogens may serve as an indicator of the foeto-placental unit function during either the physiological or pathological pregnancy.