I think it is a little photoshopped. There is some "smudging" just above the horses back that looks like someone made the lordosis or sway look worse then it really is. I think the horse is old and positively swaybacked, but I think the photo has been adjusted a little as well.
I have a 30 year old horse that is very sway-backed. He wasn't always that way, the older he got, the worse he got. But he's a good old boy and he's worked hard his entire life. I don't think he needs to be put down just because he is breaking down, I believe he deserves to be honored, just like an old cowboy, and that's what I'm doing, honoring him until he cannot go on.
"Be a best friend, tell the truth, and overuse I love you
Go to work, do your best, don't outsmart your common sense
Never let your prayin knees get lazy
And love like crazy"