My cats once opened a garter snake tank, let them all out and then hunted them around the house - all survived with a few scratches and cuts. But my current cat doesn't even seem to see the boas - I don't think they move around enough, and she doesn't seem to recognise even their scent as another animal. Mind you, my cat is so mellow she's practically comatose....
One thing I do do is wash my hands thoroughly after handling the cat before I hold a snake - I've never had a problem, but small mammal scent is small mammal scent and I don't want a mistaken food bite.