She had a terrible horse accident a few years ago (she was trampled by her horse and spent a very long time in the hospital). A lot of her songs since then have been about that in some way, including most of Misery is a Butterfly. I think this song is about how she knows her horse's true nature now, and can't trust it as fully. The references to scars are literal--she's probably covered with them. "The Dress" might be referring to the dress that she wore the day of the accident; perhaps the dress caught the horse's eye while she was riding and spooked it, causing it to hurt her.
She had a terrible horse accident a few years ago (she was trampled by her horse and spent a very long time in the hospital). A lot of her songs since then have been about that in some way, including most of Misery is a Butterfly. I think this song is about how she knows her horse's true nature now, and can't trust it as fully. The references to scars are literal--she's probably covered with them. "The Dress" might be referring to the dress that she wore the day of the accident; perhaps the dress caught the horse's eye while she was riding and spooked it, causing it to hurt her.