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Venereal diseases caused by bacteria are important to the equine industry due to economic losses caused by decline of conception rate in breeding horses. Therefore, identification of infected animals as well as the implementation of appropriate managerial procedures based on accurate diagnosis is critical. In this study, two types of multiplex real-time polymerase chain reaction with high sensitivity and specificity were developed for the simultaneous detection and differentiation of five commonly associated bacterial pathogens of venereal diseases in horses, consisting of Taylorella equigenitalis, Taylorella asinigenitalis, Pseudomonas aeruginosa, Klebsiella pneumoniae and Streptococcus zooepidemicus. The assay was applied to samples collected as part of the surveillance of T.equigenitalis infection in South Korea. Swab samples collected from horses in 2015 were tested. T. equigenitalis and K. pneumoniae was detected in 21 (21.0%) and two (2.0%) samples, respectively. No samples were positive for T. asinigenitalis, P. aeruginosa, and S. zooepidemicus. Application of this assay to an existing surveillance program has allowed for an enhanced surveillance for a wider range of venereal diseases of equine to be implemented in South Korea.

Contagious equine metritis (CEM) is a highly contagious venereal disease of the equid species caused by the bacterium Taylorella equigenitalis . CEM has been reported from at least 30 countries across the world but in Asia, Japan has been the only country that had previously reported CEM, which was successfully eradicated in 2010. Since then, there had been no reports of CEM in Asia, but during the course of this study to test Thoroughbred horses in South Korea for the possible presence of CEM, a total of five strains of T. equigenitalis were isolated from four stallions and one mare which had shown no clinical signs indicative of the disease. The isolated bacteria were coccoid rod-shaped, gram negative, and were positive for oxidase, catalase and phosphatase tests. Sequencing of the 16S rDNA gene and phylogenetic analysis confirmed that the five isolates were T. equigenitalis , which showed high-sequence identity (99%–100%) with other T. equigenitalis strains. All Korean isolates were sensitive to streptomycin. This study describes the first isolation and characterization of T. equigenitalis in Thoroughbred horses raised in South Korea, representing the reintroduction of CEM into Asia.