Embryo transfer induces a subclinical endometritis in recipient mares which can be prevented by treatment with non-steroid anti-inflammatory drugs.

The study suggests that treating mares with non-steroidal anti-inflammatory drugs (NSAIDs) after embryo transfer can help prevent the onset of subclinical endometritis, an inflammation of the uterus not detected by normal examination.

Research Milestones

• The study was conducted to understand whether subclinical endometritis, a typically undetectable uterine infection, occurs after embryo transfer in horses.
• The experiment divided recipient mares into three groups. Some were treated with meclofenamic acid, some with flunixin meglumine, and the rest were left untreated.
• Four days post the embryo transfer, embryos were collected back for further analysis. Histology and PCR analysis were performed on endometrial biopsies to check for inflammation markers, while bacteriological swabs gathered information on any bacterial infestation.
• In addition to these, the release of progesterone and prostaglandin F(2alpha), hormones essential for pregnancy, were also analyzed in the recipient mares after the embryo transfer.

Key Findings

• The results revealed that four days after the embryo transfer, the treated groups – both those given meclofenamic acid and flunixin meglumine – showed reduced signs of inflammation. Specifically, the number of neutrophils, a type of white blood cell involved in inflammation, was reduced.
• The level of expression of mRNA for inflammatory cytokines, proteins crucial for cellular signaling during immune responses, did not show any significant difference among the groups.
• Treatment with meclofenamic acid led to a higher expression of endometrial prostaglandin-E-synthase compared to the flunixin meglumine group. This enzyme is key in the production of prostaglandins, a group of lipids involved in dealing with injury and illnesses.
• In the untreated group, three out of nine mares experienced preterm luteolysis. This occurrence, along with higher levels of prostaglandin release and the higher number of COX-2 positive cells (enzymes involved in inflammation and pain), is indicative of a larger inflammatory response.
• Notably, very few of the bacteriological swabs were positive, suggesting that bacterial infection was not a primary cause of the inflammation.

Conclusion

• The study concluded that treating mares with NSAIDs post embryo transfer can help inhibit the endometrial inflammatory response that often follows.
• It was also observed that meclofenamic acid may have advantages over flunixin meglumine by having a different effect on prostaglandin synthesis which may ultimately not impede the mobility of the embryo.