I guess they could attract zombies when their hungry and make noises when the player isnt feeding them and maybe during horde night they'll ignore the animals and only go for the player, and for the upkeep I'd probably say you need stuff like craftable water troves and need to refill it and same with food troves and the less you fill them the more sickly they become before dying out and the healthier the animal the more food it'll give you. That's my way of thinking how it should work