I know dogs dream, cats too. So its a safe bet that horses dream as well.
I was just throwing paint around on this one and then I saw a horse in a splotch. I encouraged it a little bit and thought If I was a horse I'd be proud to have a dream like this. I would be a really exciting horse. If you were Alexander's Horse, fighting your way across Asia, you might have dreams like this. Do horses get PTSD? I can't answer that.
One reason I'm positing this painting is that what's going on in the details of the paint is similar to what I like about glass, its capability for chaos.