The expansion of urban areas take humans and domestic animals into the wild environment, favoring the transmission of pathogens among species. This issue has implications for environmental conservation, since emerging infectious diseases in wild mammals can affect their populations leading to extinction. This scenario has been reported in several protected areas around the world, and here we highlight our study at Carlos Botelho State Park (CBSP), São Paulo State, Brazil. We investigate the infection by Leptospira in domestic dogs that live on the edge of CBSP, and move freely inside the Park without supervision of their owners. In 2015 and 2016, 10% (35/350) and 6.3% (25/396) of the animals were seropositive, respectively. Among the 252 dogs sampled in both years, six were seropositive. Of the 13 serovars tested, the most common were L. cynopteri (55.5%), L. autumnalis butembo (14.8%), and L. grippotyphosa (9.2%). In addition, other studies found that these three serovars also were detected in wild canids, felines, cervids, primates and marsupials in the state of São Paulo. Our investigation suggest that these infectious agents can be transmitted from these domestic dogs to wild animals of the CBSP. Knowledge of Lepstospira and their hosts help to understand the dynamic disease improving actions for prevention and control policies. Our results suggest that immunisation of domestic dogs and health education campaigns are the priority actions to avoid diseases on wild and domestic animals, mainly near to protected areas.