I have a 21 year old mare that has been going blind over the past couple years. She is now totally blind. While she seems to be coping, i'm not sure if she is happy. She is a nervous mare and when we ride our other horses and have to leave her home, she gets upset. She gets turned out in a safe arena every day and is stalled at night. She spends most of the time standing in a corner. We go out of town on occasion and have a pet sitter come over. I'm getting more nervous about the pet sitter possibly getting hurt. Is it cruel to keep her going? Is it cruel to let her go? I need advice!