Surveillance of Parvovirus in Free-Roaming Dogs in the Qinling Mountains and Assessment of the Risk of Cross-Species Transmission to Giant Pandas

To assess the risk of cross-species transmission of canine parvovirus (CPV) from free-roaming dogs to wild giant pandas in the Foping National Nature Reserve, we collected rectal swabs and serum samples from dogs and fecal samples from giant pandas seasonally (August 2024–August 2025), combined with population surveys and GPS home-range tracking. Vaccination coverage declined from 54.2% to 36.4%, while the proportion of susceptible dogs rose from 8.7% to 29.5%. The CPV nucleic acid positive rate in dogs was 3.9% (4/102, all sub-adults, three deaths), whereas all giant panda samples were negative. Based on individual–seasonal exposure, the serum exposure rate was 30.4%, with immature dogs at significantly higher risk than adults (OR = 5.37). Home-range overlap between dogs and giant pandas (95% KDE: 19.17% in cold seasons vs. 2.61% in warm seasons) and encounter probability were markedly higher in winter and spring. Canine-derived CPV strains possessed the molecular potential to infect giant pandas. In summary, CPV persists long-term in free-roaming dog populations, summer vaccination has not established an effective immune barrier, and winter–spring is a high-risk window for cross-species transmission. We recommend enhanced winter–spring immunization, spatial control measures, and quarantine protocols for incoming dogs.