Thanks, Dennett. Yes, Mo was scowling, she did that all the time.
She was in constant pain, although we didn't know how much until the end. she was very intolerant of human touch, and was quite happy to slash and bite with no provocation.
She had assorted medical issues which had gone untreated with her previous owner. By the time we got her, she was beyond treatment. We did manage to alleviate some issues. Her claws were so overgrown they had imbedded into her pads, so we were able to get those clipped and the infection treated.
We tried to keep her as comfortable as possible, but finally, when she stopped eating and drinking we had to let her go.