Thanks for the question.

Yes, those pesky bunnies can do this. From your pictures it would appear that they have nibbled away some of the lower branches. However I am not sure that you can completely blame the rabbits. They normally just nip away on the ends of branches and not remove them entirely. Perhaps deer might also be culprits? Whomever, it is extremely unlikely that these lower branches will grow back. There is not much you can do at this time to alleviate the situation. Your arbor vitae will not die.  The damage has already been done. What is more likely to occur is that the upper branches will grow further out and droop down, largely covering the bare areas that are now exposed. Hindsight is always good advice as to what should have been done last fall. Your arbor vitae are testimonies to the need to enclose your shrubs with protective fencing in advance of winter. I would not dig them up and replace them. Just let them grow and expand. I would venture to say that within a couple of years or so, they will look just fine. BUT!!, put some fencing around them this fall (2022) to prevent further expansion of this problem.

Thanks for using this forum.