Oh my god. That's just terrible. I'm considering going into vet tech training myself, but it's stories like this that make me second guess whether or not I'd be able to handle it without beating myself up for being in the same species as someone who would do this sort of thing to an animal.
Either way, you're helping him out the best you can, and that's all we can do. Big kudos for that and I hope he pulls through nicely.