HELP! Is there any chance?

Cat got ahold of one of these babies 😭 Brought them in from the barn lastnight because the temp dropped and even having the bin INSIDE of a locked dog crate, one of our cats woke me up with this baby chirping away in his mouth. I assume I caught it quick but damage was already done. He’s able to walk around a little, hold up his head, drink with assistance & poop but is mostly just sitting by the heat. Is there any thing we can do? Should we humanely put it out of its misery? It’s been about 5 hours and he seems to be getting stronger, but still weak. What can I do?!