Uterine clearance of non-antigenic markers (51Cr) in response to a bacterial challenge in mares potentially susceptible and resistant to chronic uterine infections.

This research focused on understanding how well mares’ uteruses can physically remove non-antigenic elements (in this case, 51Cr microspheres) when faced with an infection. The results showed that mares more prone to long-term uterine infections had a considerable delay in the removal of these elements compared to those that are more resistant.

Study Objective and Method

• The research was carried out to understand the physical ability of mares’ uteruses to eliminate non-antigenic 51Cr microspheres in the presence of an infection.
• Mares both susceptible and resistant to chronic uterine infections were used for the study, allowing for comparison between different physiological responses.
• The mares were subjected to intra-uterine bacterial infections. Based on the reproductive history, rectum examination and endometrial biopsies, mares were categorized as potentially resistant or susceptible.
• Streptococcus zooepidemicus was infused into the mares on the third day of their oestrus followed by an inoculation of 51Cr labelled microspheres. This was done to replicate an infectious environment and to track the subsequent clearance process in the uterus.

Data Collection and Results

• After 24 hours of infection, the uterus was cleaned to recover any remaining microspheres. This procedure was repeated over two more cycles to assess the retention of these microspheres at 48 and 96 hours post-infection.
• The results showed that mares classified as potentially susceptible to chronic uterine infections demonstrated a significant delay in the physical clearance of the microspheres compared to the resistant mares.
• In mares classified as potentially resistant, the retention of the microspheres was not significant 24 hours after inoculation. However, mares susceptible to infections failed to clear the microspheres even after 96 hours post-inoculation.

Conclusion

• The study concludes that the physical ability of the uterus to remove infectious agents may play a critical role in the reproductive health of the mare and act as a first line of defence against uterine infections.
• The quicker clearance rate in resistant mares suggests that inherent physiological differences may exist between individuals that can affect their susceptibility to ongoing infections.