At the time, there was doubt as to whether cats could catch covid and infect humans, and the doubt was not only raised in Britain.
If it had been proved to be the case, presumably cat owners would have been given the option of keeping their cats indoors as is done during th attacks of avian flu with all domestic poultry.
But it would entirely have depended on how serious the threat of infection had proved to be.
During outbreaks of foot and mouth disease, all animals including cats and dogs are destroyed on the infected farms, and any animal that contracts rabies must, by law, be put down immediately.
We can all be glad that the threat either proved to be non-existent or far less serious than thought to start of with and that we were not faced with an enforced decision to have our pets put down.