Altered secretion of selected arachidonic acid metabolites during subclinical endometritis relative to estrous cycle stage and grade of fibrosis in mares.

This is a study exploring how subclinical endometritis (SE), a common and often asymptomatic condition in mares, influences the secretion of key inflammatory mediators in the endometrium. The researchers concluded that SE alters the balance of these substances, which may have implications for a mare’s reproductive health and fertility.

Background of the Study

• The research was prompted by a common concern among breeders: mares that fail to become pregnant despite repeated breeding attempts.
• Without the typical signs of clinical endometritis, the mares may be suffering from subclinical endometritis (SE), an inflammation of the endometrium that often presents without visible symptoms.
• Infectious agents are typically responsible for initiating this condition, and they disturb the balance of the endometrium by altering the production and secretion of key inflammatory mediators, including cytokines and arachidonic acid metabolites.

Hypothesis and Methodology

• The study aimed to verify the hypothesis that SE impacts the immune endocrine status of equine endometrium.
• The researchers examined the secretion of five particular substances, which included several prostaglandins and leukotrienes, all of which serve key roles in immune response and inflammation.
• The study sample consisted of 82 warmblood mares with known breeding histories. They were classified by their health status and the severity of their subclinical endometritis, as assessed through histopathologic analysis.
• They also looked at the impact of the estrous cycle stage and the grade of fibrosis on the secretion of these factors.

Findings

• The study showed that the secretion profiles in mares with SE varied from healthy mares for several of the studied factors.
• Specifically, the production of prostaglandin E2 and 6-keto-PGF1α was found to increase in those with SE, while the secretion of leukotriene B4 and leukotriene C4 was decreased.
• These variations were observed regardless of the degree of inflammation, and occurred independently of any fibrotic changes in the endometrial tissue.
• However, the secretion of leukotriene B4 did change in the presence of fibrosis.

Implications

• The findings show that SE does have a significant influence on the endocrine status of the equine endometrium. This fact may partly explain why some mares have difficulty becoming pregnant.
• The altered balance of these key mediators could negatively affect a mare’s reproductive health and fertility over time, and it underscores the value of early identification and treatment of SE.