I know that lots of folks here don't agree with sedating a pet, and maybe you are one of them, but a little behavior modification via drug therapy may just get her out of the frantic habit of knoshing on her tail. Amitripline (sp) can be applied to the ear and it really relaxes the animal, quickly and effectively. I suspect a short term dose may be in order. I think, although I am not sure, but I think Mr. Magoo was on a mood altering drug for a short period of time.

Good luck Chris and "could you find a bigger cone?"..... my gosh Ebby, what is it going to take? Maybe you should put the cone on the other end of her!