Zoonotic risk of SARS-COV-2

At the time of writing, the number of cases of SARS-COV-2 in animals is increasing, but there remains no evidence that these infected animals are a zoonotic risk. Animals that have tested positive seem to have contracted the infection from people (reverse zoonosis), although it would be incredibly difficult to prove, on an individual case basis, whether a cat was infected by the owner or vice versa as many infections in animals are clinically silent.

Any animal has the potential to be a fomite, although accurate information about how long coronavirus is viable on the coat and what sort of infectious dose could be delivered from an animal from an infected household with virus on the coat is lacking. Currently reasonable advice seems to be hand washing which should almost completely negate the risk apart from aerosolising virus during stroking.

What is evident is that a number of animal groups are at risk: chiroptera (bats), felids, mustelids (such as ferrets and badgers), rodents and primates. Experimental evidence suggests that cats can be infected intranasally (all be it with a relatively large viral dose) and they will excrete for a short time and can infect other cats housed in close proximity. However, the duration of contact needed for productive transfer of infection from cat to cat has not been examined. Most infected cats showed mild or no clinical signs. One study suggested that subadult cats were more susceptible and showed more severe pathology. Based on these data, reasonable advice would suggest that animals should not be allowed to lick faces and that potentially pets from COVID-19 positive households should be kept confined as much as practicable.