Spillover of SARS-CoV-2 to domestic dogs in COVID-19–positive households: A one health surveillance study

The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is capable of infecting multiple species through human-to-animal spillover. Human to animal spillovers have been documented both in domestic and wild animal species. Due to close contact in shared households, pet dogs may be at increased risk for contracting the SARS-CoV-2 virus from infected individuals in the same household. In this study, we have analyzed serum samples from dogs (n=196) from Pennsylvania during 2021-2022 for the presence of SARS-CoV-2 specific antibodies. The dogs in this analysis included those that were exposed to individuals of the household, who had history of recent SARS-CoV-2 infection, and from dogs with no known history of potential exposure to SARS-CoV-2. Our analysis found a significantly higher seroprevalence (68 %) among the dogs with exposure to SARS-CoV-2 infection from individuals from COVID-19 positive household compared to other dogs. Our study found the overall seroprevalence of 12.24 % among dogs as determined using a surrogate virus neutralization test (sVNT). All sera that were positive by sVNT were also positive by pseudovirus neutralization test (pVNT) except for sera from one dog, likely due to a lower antibody response. The antibody titers using the panel of spike pseudoviruses in pVNT test showed higher titers against the Delta, Gamma and Alpha variants compared to Omicron. We also tested the diagnostic capabilities of a lateral flow assay (LFA) developed by Zoetis by comparing it to sVNT and pVNT. The LFA showed sensitivity and specificity of 85 % compared to sVNT and 75 % compared to the pVNT indicating its potential for field use. These findings provide serological evidence of SARS-CoV-2 spillover to pet dogs and underscore the importance of continued surveillance in companion animals as part of a One Health approach, especially as new viral variants continue to emerge.