You live in NM right? Dry, no humidity? Chances are, she suffers from dry skin, just like alot of people do from that region; I'm from AZ and I have to make sure I drink lots of water, and apply lotion to ensure my skin retains moisture. I would presume it's the same with horses, only you would want to make sure you apply some kind of conditioner, to make sure the skin stays healthy. None of the horses in my care have dry skin, but I make sure they get some kind of conditioning spray applied periodically; in the warm months they get bathed more frequently, and a regular condition applied, allowed to set, then rinsed.
Hope that helps And welcome to the Forum