In June–September 2021, we investigated severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infections in domestic dogs and cats (n = 225) in Bangkok and the vicinities, Thailand. SARS-CoV-2 was detected in a dog and a cat from COVID-19 positive households. Whole genome sequence analysis identified SARS-CoV-2 delta variant of concern (B.1.617.2). Phylogenetic analysis showed that SARS-CoV-2 isolated from dog and cat were grouped into sublineage AY.30 and AY.85, respectively. Antibodies against SARS-CoV-2 could be detected in both dog (day 9) and cat (day 14) after viral RNA detection. This study raises awareness on spill-over of variant of concern in domestic animals due to human-animal interface. Thus, surveillance of SARS-CoV-2 in domestic pets should be routinely conducted.

Coronavirus disease of 2019 (COVID‐19) caused by severe acute respiratory syndrome virus type 2 (SARS‐CoV‐2) is an emerging severe acute respiratory disease affecting global human health. In this study, a large‐scale serological survey of antibodies against SARS‐CoV‐2 in dogs and cats was conducted during the first and second waves of COVID‐19 outbreaks in Thailand, from April to December 2020. A total of 3215 serum samples were collected from dogs (n = 2102) and cats (n = 1113) living in Bangkok and in the vicinities. Serum samples were tested for SARS‐CoV‐2 antibodies by using an indirect multispecies enzyme‐linked immunosorbent assay (ELISA). Positive and suspected samples were additionally tested for neutralizing antibodies by the surrogate virus neutralization test (sVNT). The indirect ELISA results showed that 1.66% (35 out of 2103) of dogs and 0.36% (four out of 1112) of cats were positive for SARS‐CoV‐2 antibodies. The sVNT results showed that all ELISA‐positive and suspected samples were negative for neutralizing antibodies. Positive serum samples (35 dogs and four cats) were obtained from clinically healthy animals and animals with mild respiratory signs aged <1–13 years living in Bangkok and Samutprakarn Provinces. In summary, a serological survey revealed evidence of anti‐N‐IgG antibodies suggesting SARS‐CoV‐2 exposure in both dogs and cats during the first and second COVID‐19 outbreaks in Thailand.