I've been in the same scenario and passed but it was tough. I had a doe that was skin and bones, broken leg and you could tell she wasn't going to make it long. I sat their thinking if I should put her out of her misery but passed. You could tell she had no muscle left and wouldn't have any meat on her. I let her stumble away but it hurt to know she would continue to suffer when I had the chance to end it for her.