Originally Posted by Brighteyes
She gets 2 pounds of Strategy once a day, along with a joint supplement. Hay wise, she eats grass hay free choice from a round bale.
Maybe it's just rough grooming (she is turned out with four other horses), but it just doesn't seem like the hair's been roughed out. Her mane looks perfectly in place, and the hair falls out uniformly from all areas, even places that have been over her blanket or so high on her neck that I doubt another horse would groom her there.
I seriously doubt its from other horses if it's falling out from the root. If other horses were the cause, it would be breakage. It's more than likely some sort of nutritional problem or illness. Does she have access to a salt and mineral block?