Detection of SARS-CoV-2 and coinfections in companion animals from COVID-19-positive owners in Southeast, Brazil.

Zoonotic pathogens are central to the One Health framework, and the role of companion animals in SARS-CoV-2 infection, particularly in co-infection scenarios, remains unclear. This study investigated the occurrence of SARS-CoV-2, hemopathogens, and co-infections in domiciled dogs and cats from COVID-19-positive households in Southeast Brazil. Between January 2021 and August 2022, samples were collected from 86 animals (48 dogs and 38 cats) in Belo Horizonte, Minas Gerais. SARS-CoV-2 was detected by RT-qPCR, and hemopathogens were identified using nested and species-specific PCR assays. SARS-CoV-2 was detected in 9.3% (8/86) of animals, including 14.6% (7/48) of dogs and 2.6% (1/38) of cats, and one canine sample was classified as Omicron BA.1. Hemopathogens were detected in 85.4% of dogs, mainly Bartonella spp. (70.8%) and Anaplasma sp. (58.3%), with frequent co-infections. In cats, Bartonella spp. (15.8%) and hemotropic Mycoplasma spp. (21.1%) predominated. None of the animals tested positive for ther order Piroplasmida or A. phagocytophilum. Most SARS-CoV-2-positive animals (75.0%) were co-infected, but no significant association was observed between viral infection and hemopathogens (p > 0.05). These findings demonstrate the circulation of SARS-CoV-2 and hemopathogens in companion animals and reinforce the relevance of One Health surveillance.