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.