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.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused the coronavirus disease 2019 pandemic in humans since late 2019. Here, we investigated SARS-CoV-2 infection in dogs and cats during COVID-19 quarantine at private veterinary hospitals in Thailand. From April to May 2021, we detected SARS-CoV-2 in three out of 35 dogs and one out of nine cats from four out of 17 households with confirmed COVID-19 patients. SARS-CoV-2 RNA was detected from one of the nasal, oral, rectal and environmental swabs of dog-A (15 years old, mixed breed, male dog), cat-B (1 year old, domestic shorthair, male cat), dog-C (2 years old, mixed breed, female dog) and dog-D (4 years old, Pomeranian, female dog). The animals tested positive for SARS-CoV-2 RNA from 4 to 30 days after pet owners were confirmed to be COVID-19 positive. The animals consecutively tested positive for SARS-CoV-2 RNA for 4 to 10 days. One dog (dog-A) showed mild clinical signs, while the other dogs and a cat remained asymptomatic during quarantine at the hospitals. SARS-CoV-2 specific neutralizing antibodies were detected in both the dogs and cat by surrogate virus neutralization tests. Phylogenetic and genomic mutation analyses of whole genome sequences of three SARS-CoV-2 strains from the dogs and cat revealed SARS-CoV-2 of the Alpha variant (B.1.1.7 lineage). Our findings are suggestive of human-to-animal transmission of SARS-CoV-2 in COVID-19-positive households and contamination of viral RNA in the environment. Public awareness of SARS-CoV-2 infection in pet dogs and cats in close contact with COVID-19 patients should be raised.

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.

Summary A cross‐sectional survey of SARS‐CoV‐2 in domestic dogs and cats was conducted in high‐risk areas, five subdistricts of Samut Sakhon Province, the epicenter of the second wave of the COVID‐19 outbreak in Thailand in February 2021. A total of 523 swab samples (nasal, oral, and rectal swabs) and 159 serum samples from dogs (n = 83) and cats (n = 93) were collected and tested for SARS‐CoV‐2 RNA and antibodies. All swab samples tested negative for SARS‐CoV‐2 RNA by real‐time RT‐PCR with three panels of specific primers and probes. Although all dogs and cats were negative for SARS‐CoV‐2 RNA, 3.14% (5/159) had anti‐N‐IgG antibodies against SARS‐CoV‐2 by indirect multispecies ELISA. Our results demonstrated SARS‐CoV‐2 exposure in domestic animals living in high‐risk areas during the second wave of the COVID‐19 outbreak in Thailand. Thus, the use of one health approach for monitoring SARS‐CoV‐2 in domestic animals in high‐risk areas of COVID‐19 outbreaks should be routinely conducted and will provide benefits to risk communications in communities.

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