Cats can eat Christmas cactus, but it's not a very nutritious food for them. The leaves and flowers of the Christmas cactus can be toxic if ingested in large amounts, so it's best to keep the plant out of reach of your cat. However, if you want to give your cat a treat, you can give them a small piece of the plant every now and then. Just make sure to monitor them closely and remove the plant if your cat starts to chew on it excessively.