Evaluation of the clinical evolution and transmission of SARS-CoV-2 infection in cats by simulating natural routes of infection.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of the current pandemic disease denominated as Coronavirus Disease 2019 (COVID-19). Several studies suggest that the original source of this virus was a spillover from an animal reservoir and its subsequent adaptation to humans. Of all the different animals affected, cats are one of the most susceptible species. Moreover, several cases of natural infection in domestic and stray cats have been reported in the last few months. Although experimental infection assays have demonstrated that cats are successfully infected and can transmit the virus to other cats by aerosol, the conditions used for these experiments have not been specified in terms of ventilation. We have, therefore, evaluated the susceptibility of cats using routes of infection similar to those expected under natural conditions (exposure to a sneeze, cough, or contaminated environment) by aerosol and oral infection. We have also evaluated the transmission capacity among infected and naïve cats using different air exchange levels. Despite being infected using natural routes and shed virus for a long period, the cats did not transmit the virus to contact cats when air renovation features were employed. The infected animals also developed gross and histological lesions in several organs. These outcomes confirm that cats are at risk of infection when exposed to infected people, but do not transmit the virus to other cats with high rates of air renovation.