People operate at a little higher level mentally than animals so it is possible that a horse would not experience the sort of panic that a person would. I don't know enough about human anatomy to know for sure. I have seen animals killed by having thier throut cut and it is not terribly pretty to watch but it is also not the worst way to go. Most vets care deeply about the welfare of animals or they would be doctors and work on people so I am betting that there was quite a bit of thought that went into killing this horse. Such things are needed for research and teaching. It may not be pretty but if it helps a vet learn to do his/her job then it was worth it.
There's nothing like the Rockies in the springtime... Nothing like the freedom in the air... And there ain't nothing better than draggin calves to the fire and there's nothing like the smell of burning hair. -Brenn Hill