Hmm, I seldom if ever had rabbit dmg, though I had rabbits eating more succulent things.
I found rabbit elimination (traps) was most effective...though they buggers kept coming back and nesting under my porch...and thus unleashing one or two floods of baby bunnies a year into the garden.

That's interesting you got rabbit damage, they must have have been really desperate unless you're saying they ate the new foliage that was pushed out in the spring. I haven't had a rabbit problem with mine although I have rabbits eat other things. I too use the trap and release method. For me, this only works when they are desperate for food in late January or February. Also, I keep watch out for rabbit nests and relocate the babies when they are old enough to leave their Mom.

I would not expect this to be a recurring problem. Hellebores are quite toxic and are usually free from predation by deer, rabbits and other furry critters. That doesn't mean they will never touch poisonous plants - much depends on the age of the individual animal and how desperate they are for food - but I'd be willing to bet that the bunnies were not feeling well after their hellebore banquet.

Most commercial deer repellants will work on rabbits as well.