High Seroprevalence against SARS-CoV-2 among Dogs and Cats, Poland, 2021/2022

SIMPLE SUMMARY: The coronavirus SARS-CoV-2 is responsible for the COVID-19 pandemic, which has kept the world in suspense since the beginning of 2020. Infected owners can transmit the virus to their cats and dogs, but it is not exactly known how often this happens. Here, we investigated samples from cats and dogs that live in households in Poland for antibodies against the virus. Antibodies are produced subsequently to a SARS-CoV-2 infection and can be detected for much longer than the virus itself. We found that approximately 18.9% of the cats and 16.0% of the dogs sampled had previously come into contact with the virus and developed antibodies. This suggests a continuous occurrence of virus transmission from infected owners to their pets. ABSTRACT: The coronavirus SARS-CoV-2 is responsible for a pandemic in the human population that has unfolded since the beginning of 2020 and has led to millions of deaths globally. Apart from humans, SARS-CoV-2 has been confirmed in various animal species, including felines, canines, mustelids, and primates. Of these species, dogs and cats are the most popular companion animals worldwide. Several seroprevalence studies have already been performed in these animal species; however, the results vary depending on the location and especially the time of sampling. Here, serum samples were collected from a total of 388 dogs and 243 cats from three veterinary clinics in two cities (Gdańsk and Olsztyn) in Poland between October 2021 and February 2022, when the country was in the midst of the fourth wave of viral spread. All sera were tested for antibodies against SARS-CoV-2 by a multispecies ELISA based on the receptor-binding domain and by an indirect immunofluorescence assay (iIFA). Overall, 18.9% of the feline sera and 16.0% of the canine sera tested positive using ELISA and iIFA. This relatively high seroprevalence among randomly selected animals is most likely related to the high case numbers in the human population and indicates a continuous occurrence of transspecies virus transmissions from infected owners to their pets. Hence, dogs and cats should be included in monitoring studies and/or outbreak investigations for a better understanding of the epidemiology of this virus.