Leptospirosis in horses is often associated with reproductive disorders. In the southern states of Brazil, horses are used for various jobs and cultural practices; nevertheless, serological surveillance for Leptospira is rare. Therefore, the objective of this study was to determine the seroprevalence of Leptospira spp. in horses in southern Brazil, as well as to identify the risk factors for infection and its impacts on reproduction. We performed microscopic agglutination tests for 12 serovars that corresponding 9 serogroup (Sejroe, Icterohaemorrhagiae, Australis, Pyrogenes, Pomona, Canicola, Grippotyphosa, Tarassovi and Ballum) in 595 samples from 60 herds. A brief history was obtained to analyze risk factors for reproductive disorders. A total of 45.9% of the tested horses were seropositive, of which the most frequent serogroups were Icterohaemorrhagiae (Icterohaemorrhagiae and Copenhageni serovars) and Ballum (Ballum serovar). Simple infections were found in 45.4% of seropositive animals, while mixed infections occurred in 54.6% of horses. There was a correlation between seropositivity and age and sex, that is, seropositivity was more frequent in animals over 6 years old and in females. There was no correlation between seropositivity and reproductive disorders. We conclude that there is a high seroprevalence of Leptospira spp. in southern Brazil with predominance of Icterohaemorrhagiae serogroup, mainly in older animals. Location, breeds, contact with dogs or other domestic animals are not risk factors, whereas gender is a risk factor. Reproductive disorders are not due to leptospirosis in the study region.

马的钩端螺旋体病通常与生殖疾病有关。在巴西南部各州，马被用于各种工作和文化习俗。然而，钩端螺旋体的血清学监测很少。因此，本研究的目的是确定钩端螺旋体的血清阳性率spp。以及确定巴西南部马匹感染的危险因素及其对繁殖的影响。我们对来自60个牛群的595个样本中的9个血清群（Sejroe，Icterohaemorrhagiae，Australis，Pyrogenes，Pomona，Canicola，Grippotyphosa，Tarassovi和Ballum）的12个血清型进行了微观凝集试验。获得了简短的历史来分析生殖疾病的危险因素。总共45.9％的被测马是血清阳性的，其中最常见的血清群是Icterohaemorrhagiae（Icterohaemorrhagiae和Copenhageni血清型）和Ballum（Ballum血​​清型）。在45.4％的血清反应阳性动物中发现了简单感染，而在54.6％的马中发生了混合感染。血清阳性与年龄和性别之间存在相关性，即 血清阳性在6岁以上的动物和雌性动物中更为常见。血清阳性与生殖疾病之间没有相关性。我们得出的结论是：钩端螺旋体属。在巴西南部，以Icterohaemorrhagiae血清群为主，主要存在于较年长的动物中。位置，品种，与狗或其他家畜的接触不是危险因素，而性别则是危险因素。生殖失调不是由于研究区域的钩端螺旋体病引起的。