# Finding the hiding spots: uneven distribution of pathogenic Leptospira spp. in the bovine genital tract

## TL;DR

This study shows that pathogenic Leptospira bacteria are unevenly spread in the reproductive system of cows, with the highest detection in the uterine body, which should be prioritized for testing.

## Contribution

The study identifies the uterine body as the most reliable site for detecting Leptospira in bovine genital tract infections.

## Key findings

- Pathogenic Leptospira DNA was detected in 55% of cows, with the highest positivity in the uterine body.
- Only 7.5% positivity was found in the apex of the uterine horns, and no detection in the base of the uterine horn or oviducts.

## Abstract

Bovine genital leptospirosis (BGL) is a chronic reproductive disease caused by pathogenic Leptospira spp., whose uneven distribution in the genital tract may compromise diagnosis.

This study evaluated the presence of pathogenic Leptospira spp. in different regions of the bovine reproductive tract of naturally infected cows to identify the most reliable anatomical site for molecular detection.

Oviducts (OVID) and uterine fragments from the uterine body (UB), base of the uterine horn (BUH), and apex of the uterine horns (AUH) were collected post-mortem from 40 cows.

Pathogenic Leptospira spp. DNA was detected by lipL32 PCR in at least one anatomical site in 55% (22/40) of animals. The highest positivity rate was observed in UB (20/40; 50%), whereas AUH (7.5%), BUH (0%), and OVID (2.5%) showed no or minimal detection.

The findings demonstrate that pathogenic Leptospira spp. are unevenly distributed within the bovine reproductive tract, with a clear preference for the uterine body. This anatomical site provides the greatest diagnostic accuracy and should be prioritized for molecular testing to minimize false-negative results and improve BGL surveillance.