What beautiful horses they are! I can certainly see why you want that lead edited out! I edit a lot of photos and when I saw the topic of your post I was going to volunteer to do it, but I think that's beyond my capabilities. To take that rope out, I think you'd be left with a bare, white stripe where it used to be. The horse's color would have to be "hand painted" in. That in itself could be done, , by "copying" coat color from another area of the horse, but since the rope is covering part of the eye, I don't think you'd ever get a good picture, as the eye itself would have to be reconstructed by hand.
I'm sure there are digital artists capable of doing it, but I am not that talented. I sure hope someone volunteers. What a beautiful picture it would be!
SandyWI