Changes in urinary and plasma oestrone sulphate concentrations after induction of foetal death in mares at 45 days of gestation.

The research investigated the changes in urinary and plasma oestrone sulphate (E1S) concentrations after the intentional termination of a fetus in horse mares at 45 days of gestation. The findings revealed that the concentrations of E1S, which increase during early pregnancy, significantly dropped after inducing fetal death, suggesting a link between these levels and a viable pregnancy after the 45th day.

Experimental Setup

• The researchers induced foetal death in 10 Standardbred mares at the 45th day of gestation. This was achieved by introducing 20 to 45 ml of hypertonic (24% W/V) saline into the conceptus via surgery.
• Additionally, ten other mares underwent a sham procedure to serve as controls in the experiment.
• The researchers collected blood and urine samples every other day between the 30th and 45th-day post-ovulation, with additional collections at 0, 3, and 6 hours relative to the infusion of saline in the treated mares or sham treatment in the control mares.
• Subsequent collections were made daily between days 46 and 55.

Observations and Results

• Measurements of E1S concentrations in urine, performed using radioimmunoassay, were observed to increase between the 34th and 36th day of gestation in both treated and control groups.
• In the mares that had been treated with saline, urine E1S concentrations declined post-operation and were significantly lower (p less than .05) than in the control group by the 50th day.
• Similarly, in plasma, E1S concentrations were noted for a significant increase between the 36th and 40th day in both sets of mares.
• The surge in E1S was followed by a rapid decline in the saline-injected mares after treatment. By the 48th day, the plasma E1S concentrations in the treated mares were also significantly lower than the control group (P less than .05).

Conclusion

• The study concludes that urinary and plasma E1S concentrations observe a quick increase during the early stages of pregnancy.
• A major observation was the association of these E1S concentrations with a viable foetus after the 45th day of pregnancy.