I have a thought and it's just a thought. With the age of your two cats effected, is there a possibility that the cats were already sick and they ate the leaves or chewed on the leaves trying to throw up??? My kitties do this all the time with grass and I've seen my dogs do this same thing many times. I have watched them eat the grass and within moments get sick. SO, this is just one of those things that I've always assumed was true, the following: A cat or dog eats grass to induce vomitting. I have no idea if there is any proof to this.
I've never seen any of my animals specifically eat a daylily leaf.
