Determination of conjugated oestrogens in maternal blood plasma and urine for pregnancy diagnosis and monitoring of foetal well-being in the mare

G Schuler, B Hoffmann
1999 Pferdeheilkunde  
Due to the distinct differences of oestrogen concentrations in pregnant and non pregnant animals the radioimmunological determination of conjugated oestrogens in maternal blood plasma or serum js a highJy reliable method for pregnancy diagnosis in mares during the interval corresponding to the phase of placental oestrogen production between around days 70 80 after mating/insemination and parturition. As placental oestrogen biosynthesis depends on precursors provided by the foetal gonads, any
more » ... s of foetal vitality is strictly associated with a decreased placental oestrogen production. Therefore, oestrogen concentrations are a useful parameter for the monitoring of foetal wellbeing in cases of unclear symptoms of impaired pregnancy. Prior to the onset of placental oestrogen production determination of ovarian estrone sulfate can also be applied (> day 40). However, pregnancy diagnosis may be problematic due to slightly overlapping values between 1 ng/ml to 2.5 ng/ml likewise occurring in mares at oestrus and a minor fraction of pregnant mares. The determination of urinary conlugated oestrogens can be used as a non-invasive alternative to the measurement in blood plasma within the interval correspondlng to the phase of placental oestrogen production (> day 80). Prelimlnary results also suggest that ovarian oestrogen production between days 40 and 80 after mating (insemination) may be monitored for pregnancy diagnosis, but the preliminary cut-off level at 175 ng/ml needs further confirmation.
doi:10.21836/pem19990628 fatcat:z6622jumfnhlrjqgczit7oykoe