Data_Sheet_1_A Diagnostic Survey of Aborted Equine Fetuses and Stillborn Premature Foals in Denmark.pdf

Background: Loss of pregnancy in mares can have many different causes, including both infectious and non-infectious conditions. Extrapolation of findings from other studies is often uncertain as the significance of each cause varies across regions. Causes of pregnancy loss in mares have never been thoroughly studied in Denmark, so a prospective cross-sectional cohort study targeting the entire Danish population of pregnant mares was performed over a period of 13 months to obtain knowledge of the significance of individual causes. Fifty aborted or prematurely delivered stillborn fetuses were submitted for necropsy and examined by a panel of diagnostic laboratory methods.
Results: Overall, a cause of fetal loss was established for 72% of the examined cases. Most cases (62%) were lost due to a non-infectious cause, of which obstruction of the feto-placental blood circulation due to severe torsion of the umbilical cord was most prevalent. Pregnancy loss due to a variety of opportunistic bacteria, including bacteria not previously associated with abortion in mares, accounted for 12%, while equid alphaherpesvirus (EHV) type 1 was the cause of pregnancy loss in 8% of the cases. EHV type 4 and Chlamydiaceae species were identified in some cases, but not regarded as the cause of fetal loss.
Conclusion: Umbilical cord torsion was found to be the most prevalent cause of fetal loss in Danish mares, while infectious causes such as EHV type 1 and streptococci only accounted for a minor proportion of the losses. The study highlights the need for defined criteria for establishing an abortion diagnosis in mares, particularly in relation to EHV types 1 and 4.

**背景**：母马妊娠丢失的病因复杂多样，涵盖感染性与非感染性病症。由于不同区域中各病因的临床重要性存在差异，对其他研究结果进行外推往往缺乏确定性。丹麦此前尚未对母马妊娠丢失的病因开展过全面研究，为此研究团队针对丹麦所有妊娠母马群体开展了一项为期13个月的前瞻性横断面队列研究，以明确各病因的临床重要性。研究共收集50例流产或早产死胎样本进行尸检，并通过一系列诊断实验室检测方法完成检查。

**结果**：总体而言，72%的受检病例明确了胎儿丢失的病因。其中62%的病例由非感染性病因导致胎儿丢失，最常见的非感染性病因为重度脐带扭转引发的胎儿-胎盘血液循环障碍。多种机会性致病菌（包括此前未被证实与母马流产相关的菌种）引发的妊娠丢失占比为12%；马α疱疹病毒1型（equid alphaherpesvirus type 1, EHV-1）导致了8%的妊娠丢失病例。部分病例中检测到马α疱疹病毒4型（EHV-4）和衣原体科（Chlamydiaceae）物种，但未将其认定为胎儿丢失的病因。

**结论**：本研究发现，脐带扭转是丹麦母马胎儿丢失的最常见病因，而马α疱疹病毒1型、链球菌等感染性病因仅占胎儿丢失病例的极小部分。研究强调，亟需建立统一的母马流产诊断标准，尤其是针对马α疱疹病毒1型和4型相关的流产诊断。