LeAnn, in nature you just never know what will happen. That snake may very well go on and survive for a good long time.
I saw a big(at least 3 ft.) female the other day with huge, horrendous scars, and they looked like they'd been there a long while. Whatever it was that happened to her, it looked like something that would have been quite serious when it first occurred, but she seemed to be hanging in quite well now.
I think you made a good decision here -- it's always a hard choice, though.
