Species of genus Chlamydia are important pathogens of animals, with a worldwide distribution and broad host range. Some species, such as Chlamydia psittaci, also pose a zoonotic disease risk. Abortion is one of the many diseases that has been associated with chlamydial infections in animals, with most attention focused on the economic impacts to sheep production. The role of chlamydia in equine abortions is unknown. Using the family-specific 23S ribosomal RNA (rRNA) Chlamydiaceae real-time PCR, we tested 169 formalin-fixed, paraffin-embedded fetal membrane samples from 162 equine abortion cases collected between 2000 and 2018 in Switzerland. Two equine abortion cases (1.2%) tested positive for Chlamydiaceae. Further analyses by the species-specific 23S rRNA ArrayMate microarray and sequencing of a fragment of the 16S rRNA gene revealed C. abortus and C. psittaci. In both cases, equine herpesvirus 1 was also present, which might have been the abortion cause, alone or in synergy with Chlamydia. The prevalence of abortigenic chlamydial species in equine abortion cases in our study was significantly lower than rates described elsewhere. Zoonotic chlamydial agents present in equine fetal membranes nevertheless should be considered a potential risk to humans during foaling, abortion, or stillbirth.

衣原体属是动物的重要病原体，在世界范围内分布并且宿主范围广泛。一些物种，例如衣原体（Chlamydia psittaci）也具有人畜共患疾病的风险。流产是与动物衣原体感染有关的许多疾病之一，其中最受关注的是对绵羊生产的经济影响。衣原体在马堕胎中的作用尚不清楚。我们使用家庭特异性23S核糖体衣原体实时PCR，从2000年至2018年在瑞士收集的162例马堕胎病例中测试了169份福尔马林固定，石蜡包埋的胎膜样品。两例马堕胎病例（1.2％）经检测为衣原体阳性。通过物种特异性23S rRNA ArrayMate微阵列进行的进一步分析和对16S rRNA基因片段的测序表明，流产的梭状芽胞杆菌和鹦鹉热梭状芽胞杆菌。在这两种情况下，马疱疹病毒1也都存在，可能是单独或与衣原体协同作用的流产原因。在我们的研究中，马堕胎病例中的人工流产衣原体物种的发生率明显低于其他地方所述的比率。但是，马驹胎膜中存在的人畜共患衣原体制剂应被视为在产驹，流产或死胎时对人类的潜在危险。