Discuss the spread of Toxoplasma gondii and refute the notion that killing all cats is an effective solution to prevent the spread of the parasite.
Toxo comes from all cats-not just feral ones.  And has lots and lots of intermediate carriers of many species-including some endangered ones.  People too. So to get rid of toxo you'd have to kill them all, and then quarantine the state to keep it from coming in the next day.  Admit that it's just an excuse to kill cats to make people feel better, then we can have a productive conversation.