mare has a huge bald spot on forhead

Need opinions: I was gone to a show this weekend and when I came home my mare had a large bald spot on her forehead. It is about teh length of my hand and about 1/2 as wide.
My sister came to feed saturday night and she was fine and when my husband went out late sunday morning it was bald. Does not appear at all that she was kicked and doesnt look sore. When I went to pet/rub it a few more chunks fell off. Any ideas of what might have caused this? Could she have just rubbed it off and if so why all of a sudden.
Her head was fine before I left, no sign of fungal or anyhting liek that perfectly clean and soft like normal.

Perhaps if she is moulting she is rubbing it off - hippy did this, just rubbed at his face when he was moulting and ended up with a bald patch! You would think it would look sore if it had been rubbed, but hippys didnt. Anyhow, good luck!

If a patch of skin sloughed off like that, she could have had some sort of head trauma previously. She didn't need to break the skin to damage the top layer.

If it looks healthy underneath, that's quite possibly what happened.

Horses don't moult; they're not birds.

Thats what we have always called it - shedding their winter coats. And I know full well they arent birds thanks.

Yuk. Make sure it's not rain rot or ringworm. That's a pretty huge patch for either of those, but possible.

Hmmm... could she have been reaching for grass under a fence and nicked her head on the way back in? If it's continuing to rub bald it could be seasonal shedding, rub her face with one of those soft rubber mits. I find all too often people forget to brush a horse's face and legs! It could be fungal, but you seem to have ruled that out.
Good luck! Maybe it's just mare-patterned baldness :P

I know it's not from reaching under the fence because our fence is electric and she wouldnt have bumped her head on it . She is the only one of our horses that never even tries to reach under the fence
I did find a board in teh barn that could be a possibility that she was just rubbing it one there, but still not for sure

i am not sure I understand what you are saying? This skin isnt gone it's just the hair. She has never shown any sign of head trauma. Her hair and head were perfectly healthy looking when I left on friday and when my sister fed saturday night.