Had a horse choke on cubes before, It was very scary, he was even sqeeling, and streching his neck out. He got it out while I was on the phone to the vet. I found that there were 2 different sizes of cubes offered, so I started buying the smaller size and never had an issue after that...My friends horse choked on a chunk of apple before, they had no idea, because the neighbor gave the apple. Took them forever to figure out what she could possibly be choking on.
Good thing you were there to see this happen.