Mary, I know you don't want to give up on her, but it sounds like if you don't want her last days to be in a cold cage, maybe you should bring her home. If she hasn't eaten in days, there is nothing to come out - laxative or no laxative. Once they don't eat for a few days, the other organs start shutting down, and that sounds like what is starting to happen with her.

Go to her and hug her to pieces and reassure her that you love her and will miss her dreadfully.