Wow! A bunch of you gugs type faster than I do. I was typing while a bunch of posts went up. Yep Gold Star from me too. I think it was a mercy situation, and am relieved that you disposed of it too. If you hit it under those circumstances, you'd have gotten it under better too, and you didn't Know it was sick when you shot so doesn't that count? Good job and good on you, but I'm sorry as we all are you couldn't get the meat.
FWIW, I did the same thing once on a nubbin buck. Someone had shot it "for camp meat". That seems to justify shooting for the head in these parts, NOT me!. It had the whole right side of it's head missing from a gunshot and was walking down the creek trying to get a drink I suppose. I kept watching as it just wasn't normal behavior, and when it turned its head and I saw it, I had to do it. Being a Vet. I didn't think it was wise to eat it with it having an obvious infection,so I discarded the carcass as you did. Again Good on you and better luck next time.
Bill I wonder how many posts behind I am now. LOL