ABSTRACT

Background and Aim: Salmonella enterica subsp. enterica serovar Abortusequi is an important cause of infectious abortion in horses, resulting in substantial reproductive and economic losses worldwide. Despite its veterinary significance, available information on the epidemiology, diagnosis, prevention, antimicrobial resistance (AMR), and emerging control strategies remains fragmented. This review provides a comprehensive synthesis of published evidence from 2000 to 2025 regarding S. Abortusequi-associated abortions in horses and other equids. A systematic literature search was conducted using PubMed, ScienceDirect, BASE, and Google Scholar, complemented by manual screening of reference lists. Eligible studies describing epidemiology, diagnostic approaches, prevention, molecular characterization, AMR, vaccination, bacteriophage therapy, and whole-genome sequencing (WGS) were critically reviewed and qualitatively synthesized. Available evidence indicates that S. Abortusequi infection has been reported in at least 22 countries across Asia, Europe, North America, South America, Africa, and Australia, with considerable regional variation in prevalence and outbreak severity. Conventional bacteriological isolation remains the reference method for confirmation, serotyping, and antimicrobial susceptibility testing; however, molecular and serological techniques, including polymerase chain reaction, enzyme-linked immunosorbent assay, immunochromatographic assays, and loop-mediated isothermal amplification-based methods, have substantially improved diagnostic sensitivity and turnaround time. WGS has enhanced understanding of strain diversity, virulence determinants, prophages, AMR mechanisms, and phylogenetic relationships, facilitating molecular epidemiological investigations. Vaccination remains the principal preventive strategy in endemic regions, whereas bacteriophage therapy has emerged as a promising alternative for controlling antimicrobial-resistant Salmonella strains. Nevertheless, important challenges remain, including fragmented surveillance systems, geographical reporting bias, heterogeneity of diagnostic methodologies, limited field validation of vaccines and rapid diagnostic tests, and insufficient clinical evidence supporting phage therapy under field conditions. Overall, integrating comprehensive epidemiological surveillance, rapid diagnostic technologies, vaccination, antimicrobial stewardship, genomic monitoring, and innovative biological control strategies within a One Health framework will be essential for improving the prevention, surveillance, and long-term control of S. Abortusequi-associated abortions in equine populations.

Keywords: antimicrobial resistance, bacteriophage therapy, diagnostic methods, equine abortion, epidemiology, One Health, Salmonella Abortusequi, whole-genome sequencing.