Influence of intrauterine saline infusion upon the oestrous cycle of the mare.

The research study explores the effect of intrauterine saline infusion on mare’s reproductive cycle. It is found that saline infusion can trigger ovulatory heats and shorten the dioestrus phase in mare’s reproductive cycle, while being potentially harmful due to increased chances of bacterial infection.

Research Method and Participants

• The research was conducted on mares in different stages of their reproductive cycle – anoestrus, dioestrus, oestrus, and prolonged dioestrus.
• The procedure involved infusing intrauterine saline and observing the subsequent effects on the mare’s reproductive cycle.

Findings and Observations

• In anoestrus mares, saline infusion induced anovulatory heats, but this only occurred near the beginning and end of the breeding season.
• For dioestrous mares, saline infusion between Day 5 and 9 led to a return to heat 3-8 days earlier than anticipated.
• Mares in prolonged dioestrus showed ovulatory heats within 3-9 days of saline infusion.
• Infusions during oestrus did not show any noticeable effect.
• Despite being clinically harmless, repeated infusions were associated with positive post-infusion bacteriological swabs from the uterus, indicating possible bacterial infections.
• In a limited study involving two cases, saline infusion was followed by a decrease in peripheral plasma progestagen concentrations. This could potentially impact the hormonal balance and fertility of the mares.

Theoretical Implications

• The study provides evidence that mechanical factors like vaginal and cervical dilatation and use of oxytocin do not drive the impact of saline infusion. Instead, it suggests that the luteolytic effect seen might be mediated by prostaglandin, a hormone-like compound that is involved in a variety of physiological functions, including the regulation of inflammation and smooth muscle contraction.
• This research can contribute to the understanding of mare reproductive biology and could potentially inform techniques in breeding and animal husbandry.