Diagnosis of Equine Genital Leptospirosis (EGL) in mares with poor reproductive performance

Leptospirosis is a zoonotic disease caused by spirochetes of the genus Leptospira. Equine genital leptospirosis (EGL) has been described as a chronic and silent syndrome, presenting reproductive alterations such as abortion, stillbirth, placentitis, embryonic loss, repeat breeding syndrome, and subfertility. This study aimed to investigate the genital Leptospira infection in naturally infected mares with poor reproductive performance, as well as to genetically characterize the agents. A total of 41 mares with a history of poor reproductive performance were selected. Sera were collected for serology by Microscopic Agglutination Test (MAT), while urine, uterine mucus, and uterine fragment samples were collected for a lipL32-PCR screening. Samples positive at lipL32-PCR were submitted to secY gene sequencing. Considering MAT, 17/41 mares were seroreactive (41.5 %). The most frequent serogroup was Australis, detected in 13 animals (76.5 % of the reactive). Out of the 41 mares, 25 (61.0 %) were positive in lipL32-PCR and, of these, 21 (84.0 %) showed positive in at least one genital sample. Regarding secY nested-PCR, only six samples, all from the uterine fragment, were amplified, and all were characterized as Leptospira interrogans with ≥ 99 % of similarity with isolates of serovar Bratislava, from the Australis serogroup. Our results confirmed the diagnosis of EGL and highlighted the high detection rate of Leptospira DNA in genital samples of mares with poor reproductive performance.