My MFT filly who recently turned one and other than being a little bit under weight, which we are working on, is pretty healthy. But two weeks ago I found a chunk of mane missing a little higher on the neck than the withers. Over the past weeks it's gotten a little bigger. I can't think of any reason other than that she might be rubbing it away? She's up to date on shots and worming. Her mane is really thick. Any Ideas? I'll get pics as soon as I can.