Disappearing horses

I had tamed a horse and named it with a name tag, and did not have any issues for 2 or 3 days, then moved the stable, and put horse in said stable yesterday. when I log in today and go into stable, my horse is gone. also, the herd of horses where I got my horse is gone. there are only 2 other people on the server, and neither of them have been online since I rebuilt my stable

ETA: My new stable does have a water fountain. However, I have seen horses swim to the surface when ridden to the water, so I do not think my horse could have drowned