Relationship between infection, inflammation and premature parturition in mares with experimentally induced placentitis.

The research explores the correlation between bacterial infection, inflammation, and premature birth in horses with artificially induced placentitis. Detrimental consequences such as premature birth and high foal mortality rates result from the medical condition placentitis. To decrease these negative results, the aim is to understand the mechanisms of how placentitis triggers premature delivery.

Research Methodology

• The study comprised of two separate experiments.
• In the first experiment, 8 mares were inoculated with the bacterium Streptococcus equi ssp. zooepidemicus, a major equine pathogen, leading to induced placentitis. The researchers particularly studied the concentrations of prostaglandins, which are compounds with hormone-like effects, in the fluid surrounding the embryo (known as allantoic fluid).
• The results from this group were compared with a control group consisting of 4 mares.
• In the second experiment, the researchers examined the mRNA expression of certain inflammatory markers (interleukins and tumour necrosis factor) in the tissues from the chorioallantois, which is the membrane surrounding the fetus, in the mares that had been infected.
• These results were compared with another control group, this one made up of 7 mares that had delivered their foals normally.

Research Findings

• In the first experiment, the researchers found that bacterial inoculation led to 7 out of 8 mares aborting their fetuses and one birth of a premature, but viable, foal.
• The infection was associated with inflammation of the chorioallantois, isolation of the bacteria introduced, and high concentrations of prostaglandins in the allantoic fluid within 48 hours of delivery.
• Through the second experiment, it was found that all mares expressed mRNA for the selected inflammatory markers. However, those that were experimentally infected showed higher expression of mRNA of certain interleukins in both the cervical star region and tissues from placental horns.

Research Conclusions

• The study concludes that bacterial placentitis may trigger the release of cytokines, which are small proteins crucial in cell signaling, from the chorioallantois.
• Furthermore, it may also lead to prostaglandin formation, which could result in abortion or the birthing of a prematurely mature foal.

This research thereby provides potentially significant contributions to the continuing efforts to curb the high mortality rates among newborn foals due to infections and inflammation during pregnancy.