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SARS-CoV-2, the virus that causes COVID-19, originally was transmitted from animals (likely bats) to humans. And humans can transmit the virus to cats and dogs. But can these animals infect others of their species?
Researchers inoculated (intranasally) a small number of cats and dogs with SARS-CoV-2. Both species were infectable, but neither developed significant clinical disease. Cats shed virus for 5 days following inoculation, whereas dogs did not shed virus. Both species developed neutralizing antibodies against the virus. Cats sometimes developed mild respiratory signs, but dogs did not. Through aerosol transmission, cats could spread the virus to other cats. When infected cats were rechallenged with the virus, the reinfection did not lead to extensive replication and shedding of virus: Cats' immune response to a first infection was protective.
Bosco-Lauth AM et al. Experimental infection of domestic dogs and cats with SARS-CoV-2: Pathogenesis, transmission, and response to reexposure in cats. Proc Natl Acad Sci U S A 2020 Sep 29; [e-pub]. (https://doi.org/10.1073/pnas.2013102117)
Comment
Our pets are not at substantial risk from us, should we develop COVID-19. The researchers did not examine whether cats and dogs could transmit the virus to humans, for obvious ethical reasons. Previous serologic studies, and the limited viral shedding by the animals in this study, indicate that transmission to humans probably can't happen with dogs and is unlikely with cats. Finally, cats might be a useful animal model for studying vaccines and treatments for COVID-19.