Molecular detection of Chlamydia abortus in endometrial biopsies of mares from western Canada.

This research investigated the occurrence of a bacterium, Chlamydia abortus, in horse endometrial biopsies from western Canada and evaluated its association with infertility and endometritis in horses.

Background of the study

• The bacterium Chlamydia abortus is known to cause fertility problems and inflammation of the uterus (endometritis) in several livestock animals including sheep, cattle, and pigs.
• Previously, there was limited knowledge about this bacterium and its effects in horses, particularly in relation to uterine diseases.
• A recent observation raised concerns when a high occurrence of Chlamydia abortus was found in the tissues surrounding the fetus (chorioallantoises) of aborted horses in western Canada.
• This information prompted a further comprehensive study to understand the effects of this bacterium on horse fertility and uterus health.

Methodology and results

• The researchers examined 98 endometrial biopsies of horses taken in western Canada from 2014 to 2022.
• The samples were preserved and processed by formalin fixation and paraffin embedding, common preservation techniques that maintain cell and tissue structure.
• These samples were tested for the presence of Chlamydia abortus using a specific molecular tool (PCR targeting 16S rRNA) that helps identify and quantify the bacterium.
• The test was positive in 40 out of the 98 samples, and further sequencing confirmed 28 to be Chlamydia abortus.

Findings and implications

• The majority of horses with positive Chlamydia abortus cases had a history of either not being able to conceive, early embryonic loss, or abortion.
• This suggests a possible link between infection with Chlamydia abortus and fertility-related issues in horses, indicating the bacteria could be a potential cause of conception failure and abortion among horses in western Canada.
• The findings warrant further studies to explore the exact relationship and underlying mechanisms, which may potentially lead to improved diagnostic measures and treatment strategies for fertility issues in horses.