Presence and Characterization of Zoonotic Bacterial Pathogens in Wild Boar Hunting Dogs (Canis lupus familiaris) in Tuscany (Italy)

Simple Summary Wildlife is an important reservoir for several zoonotic pathogens, and wild animals can contribute to disease transmission to humans or domestic animals via direct or indirect contact. In the One Health approach, the role of wildlife and the wild environment in the maintenance and spread of zoonoses has great importance. Domestic dogs (Canis lupus familiaris) employed in wild boar hunts may be a good indicator to evaluate this. This investigation reports the presence of Leptospira spp. and antimicrobial-resistant Salmonella spp. and Yersinia enterocolitica in wild boar hunting dogs in the Tuscany region (Italy). The results obtained suggest that wildlife may be the source of pathogens detected in dogs; indeed, all pathogens may be carried by wild animals, in particular wild boar. This investigation highlights the possible risk for dogs connected to work activities. Furthermore, considering that humans could be exposed to the same pathogens during outdoor activities, constant monitoring seems necessary to evaluate the transmission risk. Domestic dogs (Canis lupus familiaris) used for wild boar (Sus scrofa) hunting may represent incidental hosts for several zoonotic pathogens. This investigation aimed to evaluate the presence of anti-Leptospira antibodies and the occurrence, antimicrobial resistance, and virulence of Salmonella spp., Yersinia enterocolitica, and Listeria monocytogenes in sera and rectal swabs collected from 42 domestic hunting dogs in the Tuscany region (Italy). Regarding Leptospira, 31 out of 42 serum samples (73.8%) were positive and serogroup Pomona was the most detected (71.4%) at titers between 1:100 and 1:400. Four Salmonella isolates (9.52%) were obtained, all belonging to serotype Infantis; two of them showed antimicrobial resistance to streptomycin, while pipB and sopE presence was assessed in all but one isolate. Concerning Yersinia enterocolitica, seven isolates (16.7%) were obtained, six belonging to biotype 1 and one to biotype 4. Resistance to amoxicillin-clavulanic acid, cephalothin, and ampicillin was detected. Biotype 4 presented three of the virulence genes searched (ystA, ystB, inv), while isolates of biotype 1 showed only one gene. No Listeria monocytogenes was isolated from dog rectal swabs. The results suggest that hunting dogs are exposed to different bacterial zoonotic agents, potentially linked to their work activity, and highlight the possible health risks for humans.