Coexistence issues

Some pets are carnivorous and can't be trusted with weaker and less child herbivorous pets like ducks. Some dogs have known to feed on ducks and this is just am example. Sometimes one has to release them i the borouod for exercise or to carl in the sun. It also follows that once a carnivorous pet marks another one as prey or actually consumes one, they have to be isolated for good. Have you ever faced this challenge of some pets being predators and others being hapless preys?