The potential role of companion animals in the transmission and pathogenesis of SARS-CoV-2 remains poorly understood. This study aimed to evaluate the susceptibility of domestic dogs to a human-derived SARS-CoV-2 Delta variant under experimental conditions. Seronegative, clinically healthy dogs were randomly assigned to control and experimental groups. The experimental group was intranasally inoculated with the strain SARS-CoV-2/Indian-Delta/KZ_Almaty/07.2021. Clinical signs were monitored, and samples were collected for hematology, biochemistry, serology (ELISA and microneutralization assay), RT-PCR, and histopathology over a 21-day period. Infected dogs exhibited mild, transient clinical signs including diarrhea, slight fever (up to 40.1°C), and mild weight loss. RT-PCR detected viral RNA only in rectal swabs on day 3 post-infection. Hematological changes included temporary reductions in leukocyte, erythrocyte, and lymphocyte counts. Antibody responses were detected by microneutralization assay and ELISA, with the former showing sustained increases through day 21. Histological examination revealed mild bronchial and alveolar inflammation, with no evidence of viral pneumonia. All control animals remained clinically and pathologically normal. While SARS-CoV-2 exposure in dogs elicited mild clinical signs and measurable antibody responses, there was no evidence of sustained viral replication or active shedding. These findings suggest that dogs are not likely to serve as reservoirs or vectors for SARS-CoV-2 transmission. Continued research is essential to monitor the interspecies dynamics of emerging coronaviruses within the One Health framework.
Keywords | SARS-CoV-2, Dogs, Susceptibility, Delta variant, Experimental infection, Serology, RT-PCR, Histopathology, Zoonosis