Well, the dogs that took my rabbit cages apart didn't eat the rabbits, just ripped them apart and left them. One of the worst cases by the way of cats damaging the ecosystem is in Australia where they are now a food source to the aboriginal peoples because they have killed off so many of the small native animals including rabbits and such. Cat bites also do serious damage to humans by the way. We have a cat and love her dearly and were worried sick when she got outside, thankfully nothing happened to her and she has never gotten out again. I have a hard enough time killing mice for my snakes and I couldn't bring myself to harm the loose dogs in my neighborhood regardless of the fact that they killed our rabbits and every night they will tear my garbage apart and leave it strewn down my ally, I would however have no problem doing it if the animal attacked my child for no reason! I am glad your sisters cat will be ok, it is sad that it happened but I completely understand why people are fed up with dealing with loose animals.