Relationship between the timing of prostaglandin-induced luteolysis and effects on the conceptus during early pregnancy in mares.

This article investigates how induced luteolysis, or the degradation of the corpus luteum, affects early pregnancy in horses. The study focuses particularly on the timing of this process and its effect on embryonic development using cloprostenol to induce luteolysis at various stages of pregnancy.

Research Methodology

• The researchers used cloprostenol, an analogue of prostaglandin F2α, to induce luteolysis in pregnant mares.
• The mares were injected on Days 12, 14, 16 or 18 of pregnancy with either cloprostenol (treatment groups) or saline (controls).
• Conceptus development was then monitored daily using ultrasonography until collected transcervically on Days 15-22, 1-4 days following the injections.

Research Findings

• Comparations were made between developing conceptuses by counting the number of somites (divisions of the body of an embryo), measuring the volume and osmolality (a measure of concentration) of the yolk-sac fluid, and assessing the concentrations of proteins, estrone sulfate and progesterone.
• The morphology of the capsule and vascular system was also assessed.
• If luteolysis was initiated on or before Day 16, most pregnancies survived until the time of collection, with the conceptuses between treated and control groups on Days 15-20 showing little variation, except for minor effects of the treatment on capsule and vascular development.
• When the luteolysis was initiated on Day 18 however, abortion often occurred within three days. The majority of the conceptuses collected were found to have degenerated, demonstrating how the timing of luteolysis can cause pregnancy failure.

Implications of the Study

• This study advances our understanding of early pregnancy failure in horses and emphasises the importance of the timing of luteolysis in conceptus development.
• The findings suggest that avoiding premature luteolysis may be essential for successful embryonic development.
• The findings could help to develop new strategies for managing problematic early-term pregnancies in mares.