I'd say the same as shubla but I would still go and take another look if I were you.
Last world I had the same thing happen when a bear aggro'd my horse, difference being it was on the edge of the world and the horse ran into the no-go zone and disappeared. I waited for ages to see if it came back, wandering up and down the cut off line in case it emerged elsewhere. Eventually I had to give up and go home believing it to be lost for good.
Later that day, like hrs later, I still couldn't let it go, it was my first tamed horse of the world and although it was only q10, lol, it meant a lot to me. I went back and again wandered up and down and to my utter surprise I did find it! It had moved quite away down from where it had crossed the line but it had emerged and I could reach it. All was right with the world again.
Another time I deliberately abandoned the same horse as I had too many horses and couldn't bring myself to kill it ... I felt so guilty and kept trying to tell myself it's a pixel horse, it's not real, stop being so silly! But ... in the end I went back for it like roughly 5 hrs later ... it was still standing in the exact same spot where I left it, lol, talk about loyalty! It was like it was waiting for me ... felt even more guilty than I did when I abandoned it!
