Evidence of SARS-CoV-2 Exposure in Cats and Dogs From Households in Romania and Long-Term Specific Seroconversion in Cats

Abstract

Introduction: The COVID-19 pandemic underscored the need to understand the zoonotic transmission of pathogens. SARS- CoV-2 has been reported to be transmitted from humans to pets, including cats and dogs, particularly after close contact with infected individuals. Studies have shown that cats are more susceptible to natural infection and can transmit the virus to other cats and humans. The zoonotic transmission route represents a risk for animal health workers. Despite global reports, data from Romania remain sparse. This study aimed to evaluate the presence of SARS-CoV-2 specific antibodies in household dogs and cats in Romania during the COVID-19 pandemic. Methods: The study was conducted at a veterinary clinic in Iasi City, Romania, from March 2020 to December 2022. Blood samples were collected from 84 cats and 82 dogs that had been in contact with COVID-19-positive owners. Plasma samples were tested for anti-SARS-CoV-2 antibodies using an ELISA test, followed by confirmation with a seroneutralisation (SN) assay. The SN assay used the SARS-CoV-2 MAD6 strain and Omicron strain to determine neutralising antibody titers. Results: ELISA testing showed a seroprevalence of 9.5% in cats and 11% in dogs. Further SN assay testing confirmed SARS-CoV-2 specific antibodies in 9.4% of cats and 2.4% of dogs. One cat maintained antibodies for over a year, though with reduced titers. Most cats’ antibodies did not cross-react with the Omicron strain, indicating limited cross-reactivity. The study highlighted higher seroprevalence and antibody titers in cats compared to dogs, likely due to more efficient viral replication in cats. Conclusions: This study provides the first serological evidence of SARS-CoV-2 exposure in household pets during the pandemic in Romania, with findings suggesting cats are more susceptible to infection from their owners than dogs. The cats that were living in households in one area of the city were prone to be infected with SARS-CoV-2 from their owners and high levels of seroconversion were detected. These results align with global reports, demonstrating that cats are particularly susceptible to SARS-CoV-2 when living with infected owners.