Differences in uterine position of reproductively normal mares and those with delayed uterine clearance detected by scintigraphy.

This study explores the correlation between the position of the uterus in mares and the speed of uterine clearance of contaminants. It discovered that mares with a uterus that tilts more ventrally, particularly those that had given birth multiple times, exhibited a delay in uterine cleaning, suggesting fertility complications.

Research Methodologies

• This research engaged 44 mares during their estrus phase. Out of these, 24 were classified as reproductively normal while the remaining 20 displayed a delayed uterine clearance. The classification was based on their ability to clear more than or less than 50% of a radiocolloid infused into the uterus within 2 hours.
• For each mare, the position of the uterus in the abdomen was established using left and right lateral flank scintigrams. These images were captured one and two hours after the infusion of the radiocolloid.
• The mares were further categorized into nulliparous (never had given birth) and pluriparous (had given birth at least once). Other important variables such as age and history of persistent uterine infections were also taken into account.
• The angles between different parts of the uterine image and the cervix, relative to the horizontal line, were measured using a protractor. Data captured was then analyzed using the General Linear Model System.

Results of the Study

• The research demonstrated that there was an observable difference in the uterine-cervical angle in mares that exhibited a delay in uterine clearance as compared to the reproductively normal ones. Specifically, a more ventral positioning was noted in the former group.
• Among the reproductively normal mares, pluriparous mares displayed a steeper angle compared to the nulliparous ones. However, there were no differences in angles when comparing left and right lateral views within the same individual.

Study Conclusions

• The study concluded that the positioning of the uterus might be a significant factor impacting a mare’s fertility, with a ventrally tilting uterus potentially contributing to a slower clearance of the uterine lumen. This could increase the probability of contamination, thus leading to possible fertility issues.
• The study also suggested that the higher incidence of a ventrally oriented uterus in pluriparous mares could be due to a greater number of previous pregnancies. This indicates that parity (number of times a mare has given birth) may play a role in altering the uterine positioning over time.