So, I'm dipping into the children's books, and this one's definitely and oldie-but-goodie!
The Blind Colt by Glenn Rounds
Originally published in 1941, and republished a quite a few times by Scholastic, this slim little paperback is charmingly illustrated and just as charmingly written. Born to a range mare running the South Dakota Badlands, a small grey colt discovers the world in all it's spiky, soft, sweet smelling and uneven wonder. Gradually, his world intertwines with that of a young boy, Whitey, who, along with his Uncle Torval, happens upon the youngster still with his mother.
As he's blind, Uncle Torval sees the colt as wolf-bait and maintains the kindest thing to do is shoot him. But Whitey pleads the colt's case, and (as with many children's stories) does a bit of sneaking around and ultimately proves his point with some assistance from an old gelding and one of the ranch dogs.
Althougth story doesn't progress much beyond the point of the colt's salvation, Rounds' postscript notes that the blind colt's tale was inspired by a his own experience.
A word on the illustrations - if you haven't ever run into Rounds' pen and ink line drawings (they're dotted throughout the margins in most of his books) do yourself a favor and check him out. Your local library is sure to have one or two of his books in the children's section, and many of his stories are still in print. While no one would ever accuse any of his horses of being "pretty" (or his people, either!), they sure do have character!