Evidence of Exposure to SARS-CoV-2 in Dogs and Cats from Households and Animal Shelters in Korea

SIMPLE SUMMARY: With the worldwide spread of COVID-19, and given the zoonotic nature of this virus, it is necessary to monitor companion animals in epidemic areas. Dogs and cats visiting local animal hospitals and animal shelters during the COVID-19 pandemic were randomly selected for inclusion in this survey. Although testing is recommended only for animals from a COVID-19-confirmed family showing clinical symptoms, this investigation was carried out in view of the highly contagious nature of the virus. Of the 1018 pets tested, we found 2 cats with the SARS-CoV-2 antigen, 16 dogs (2.38%) and 18 cats (5.20%) carrying antibodies, and 14 dogs (2.08%) and 17 cats (4.91%) carrying virus-neutralizing antibodies. Even in animal shelters, which were thought to be relatively safe from the virus, with contact with confirmed human cases being blocked due to strict self-quarantine measures, antigens and antibody positivity were detected. Since antigens or antibodies were detected in the investigated animals regardless of whether the companion family was infected, their presence may cause continuous viral circulation between humans and animals, and the disease that started with zoonosis may cause reverse zoonosis. Considering the high transmissibility of COVID-19, continuous monitoring in animals is required. ABSTRACT: The COVID-19 pandemic was caused by the zoonotic SARS-CoV-2. A variety of animals involved in human life worldwide have been investigated for infection. As the degree of infection increased, extensive monitoring in animals became necessary to determine the degree of infection in animals. The study was conducted on a sample of dogs and cats, which were randomly sampled according to the number of confirmed cases in the region. Animals from both COVID-19-confirmed households and generally disease-negative families and animal shelters were included. Tests included real-time qPCR tests for SARS-CoV-2 antigens, ELISA for antibodies, and plaque reduction neutralization tests (PRNT) for neutralizing antibodies. As a result, SARS-CoV-2 viral RNA was detected in 2 cats out of 1018 pets (672 dogs and 346 cats). A total of 16 dogs (2.38%) and 18 cats (5.20%) tested positive using ELISA, and 14 dogs (2.08%) and 17 cats (4.91%) tested positive using PRNT. Antigens of- and/or antibodies to SARS-CoV-2 were detected in the animals regardless of whether the companion family was infected; this was the case even in animal shelters, which have been regarded as relatively safe from transmission. In conclusion, continuous viral circulation between humans and animals is inevitable; therefore, continuous monitoring in animals is required.