There is a couple of sheep in a paddock next to the one I graze my horse in, so anyway when I was there today I noticed one of the sheep, well actually its kind of a big lamb, was rubbing its eye on a wood board on the fence..
So I thought oh its just itching itself but when I looked closer (it didn't run away) its eye was all covered in blood, the thing had its eye wide open rubbing like really hard onto this wooden board and there was blood all around its eye and over its actually eyeball too.
Then I thought maybe it had a thistle under its eyelid and was scratched.. but when it turned around the other eye/around the eye was covered in blood too, scratching that side as well.
It looked quite upset like it would run a short distance then sit down and do this several times, it was also itching it by using its back foot/hoof to kick at it, and was rubbing against the other sheep too.
Just as I was leaving I saw a different sheep scratching just under its eye on the fence but not as hard, and its eye was not swollen or weepy.
I was going to tell the owners but not sure if they were home, I've just never seen or heard of anything like it... looked like something out of a horror movie with the red eyes and blood running down its cheek.
Has anyone ever heard of this before?

Oh my Goodness! You NEED to tell the owners ASAP! I don't know what this could be, but it sounds like it is spreading from one sheep to another, and they are suffering! If you cannot contact the owners, I would call your local Humane Society/SPCA, or at least a vet to come out and see what the problem is. It sounds like it may be contagious, and you don't want that to spread to any of your horses if it is. I would act promptly on this, just in case.