This may not be so creepy to everyone but I watched my mother's favorite horse, one that I had been with us since he was 2 and was about my own age, die. He had a stroke and had caught his head upon his collapse in the hay manger in the barn and was unable to free himself. During a particularly hard spring rainstorm, we spent the next four hours trying to get him out (including tearing the manger apart) but he just didn't have the strength to get up again. It was so sad seeing my mother keep trying only to fail and eventually see his eyes roll back into his head.
I've seen most of the herd I grew up with pass away now. It's even more disturbing, as you cannot readily bury a horse, to have Animal By-Products come with their truck, attach a chain to a member of your family's foot, and drag them into their truck never to be seen again. The mental image has been burned into my memory and really creeps me out.