Diagnosis of bovine genital leptospirosis in asymptomatic bulls: Comparison of methods and samples under field conditions.

BACKGROUND: Bovine leptospirosis is a zoonosis of global importance that is associated with reproductive losses. Although diagnosis in females has advanced, genital infection in males remains poorly understood. This cross-sectional study aimed to compare diagnostic methods and sample types for detecting bovine genital leptospirosis (BGL) in bulls under field conditions. METHODS: Blood, urine, semen and preputial cytology samples were collected from 37 unvaccinated bulls and analysed by serology (microscopic agglutination test -MAT) and lipL32-PCR. RESULTS: Serology showed low seroreactivity (13.5%), whereas PCR detected infection in 80.5% of bulls. Leptospira DNA was identified in semen (70.6%), preputial cytology samples (50%) and urine (46.8%). PCR detected a higher proportion of positive animals than MAT (p < 0.05). The genital tract had a higher frequency of Leptospira detection than the urinary tract (p < 0.05), with no significant difference between semen and preputial cytology samples (p > 0.05). LIMITATIONS: The sample size was small, and the number of samples collected differed among sample types. CONCLUSIONS: PCR using genital samples-semen and/or preputial cytology-is the method of choice for diagnosing BGL in asymptomatic bulls.