Well, you can cut it yourself, or let her continue to step on it and trim it on her own.
Personally, I save my tail from the weather in the winter to keep it nice for the other seasons. I braid it with a strip of old sheet (below the bone!), tie it up, wrap it with Vetwrap and there it stays all winter. No ice balls, and it is gorgeous come spring. Just make sure that anything you do it below the bone and that you brush it first. I also put a hair conditioner on it prior. You will think that a lot of hair comes out when you undo it, but nothing other than all the hair you would have brshed out all winter. Works like a charm.