Infection of SARS-CoV-2 in domestic dogs associated with owner viral load

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-positive pet owners are reported to be a risk factor for infection of their pets; however, the influence of the viral load and associated risks has not been fully established. This study aimed to assess potential association of viral load in owners with the presence of SARS-CoV-2 infection in their dogs. Of 20 SARS-CoV-2-positive pet owners from 13 families in Curitiba, Brazil, 5 of 22 (22.7%) dogs were positive for SARS-CoV-2. Viral presence was detected in oropharyngeal samples for 2 of 5 (40.0%) dogs at 8 and 9 days after the first positive sample. Detection of SARS-CoV-2 in these dogs was associated with higher viral loads in the owners and close owner contact. All 5 RT-qPCR-positive dogs had antibodies to at least one viral protein tested in the serological assay. Molecular detection of SARS-CoV-2 in dogs was statistically associated with clinical signs in owners such as cold, cough, or diarrhea (P = 0.039), number of positive persons in the household (P = 0.002), and higher viral load (P = 0.039). Such findings serve as a warning for risks of human to dog infection, mainly due to sharing beds and other close interactions without protection. In conclusion, people with coronavirus disease 2019 (COVID-19), particularly in households with multiple residents and high viral load, should take the same preventive measures when interacting with their dogs during self-isolation as they do with people.