Hmm. I never thought about cancer. Sorry for your loss! The thing that gets me is he was vet checked before (I have all my horses checked out every year) and he seemed in perfect health. He never acted sick, never took a lame step, nothing. And what gets me, I forgot to add, is he couldn't move his ears, close his eyes and his tongue just hung out of his mouth. And he was cold, really really cold.
~Started young horses in Bosca te Ador, unto the two rein the old Spanish spade, brought them along with two hands that were gentle. Some fine reining horses as ever were made~