Pregnancy failure induced by human chorionic gonadotrophin in pony mares.

This research paper explores the effect of human chorionic gonadotrophin (HCG) treatment on pregnant pony mares, observing that early administration can lead to pregnancy loss, while later stages of pregnancy appear resistant to the same.

Purpose of Research

• The study aimed to investigate the effects of human chorionic gonadotrophin (HCG) on the pregnancies of Welsh pony mares. Given the specific focus on the timing of HCG administration, the study’s purpose was to understand whether doses were more likely to cause pregnancy failure if given early on, during the first 39 days of gestation.

Methodology

• The study involved ten pregnant Welsh pony mares who were treated with a series of three intravenous injections of 2000 iu HCG. This was done on alternate days with the goal of observing the impact of these injections on maintaining pregnancy.
• The mares were divided into two groups for treatment. In four of the mares, the first HCG dose was given before the 39th day of gestation. The other six mares were first treated between the 40th and 97th days of their pregnancies.

Findings

• All four mares treated in the early stage of their pregnancies lost their conceptuses after HCG treatments. This confirmed that HCG administration during the early days of pregnancy can induce pregnancy failure in pony mares.
• In contrast, the other group of six mares, treated with HCG between the 40th and 97th day of gestation, did not lose their conceptuses. This was true even when five of these mares were given a fourth dose of HCG, indicating a possible resilience to HCG as the pregnancy progresses.
• Interestingly, two mares treated on days 36 and 38 of their pregnancies produced Pregnant Mare Serum Gonadotropin (PMSG), even though fetal death had already occurred. This could lead to further exploration into this hormonal response post pregnancy-loss.