I was riding a horse from a rental place, mind you, I had never been here before and do not know how knowledgeable or trustworthy this barn is, and I noticed something on its eye. Apart from the iris, on the white part of both eyes, were blotchy black spots all over. I was curious to know what are these? Are they harmless, do they mean anything? And is there a disease/cure? Thanks!
Extra info: The horse was mostly healthy looking, although it did look slightly underfed.