Thank you rainbow and 2sheltiesmom,
My regular vet is working so hard to try and figure this out so I really appreciate that! She's been brainstorming with other vets and the suggestion now is to test her blood again this Monday. If there is no change we will start reducing the prednisone by half. I am fine with that because that is what is making her feel so unlike herself. She thinks that if the immune system was attacking the platelets that we should have seen improvement by now. She's been on the Prednisone for almost the entire month and the Imuran for two weeks now.
The other thing to consider is the bleeding and mucous from the rectum which has since subsided since I started antibiotics. She wonders about a growth and perhaps a colonoscopy would be the next step if we still see no improvement with the blood work. She did have an ultrasound but it sounds like it is hard to see every part of the bowel.
We could also consider a bone marrow test under sedation to determine if it is that type of cancer but I would think her white cell count would be really high and it only started to elevate after starting on the Imuran.
If there is a tumor, it would be risky to remove because her platelets are so low but I guess there are platelet transfusions available. I guess we'll cross that bridge if we get to it.
I am just glad to start reducing the meds because I want her to feel a little better. I struggle with everything that is going on -- I do want her to get well but at the same time it is difficult to drug her up and see her without much happiness if we are possibly nearing the end of her life. But, I also want to be optimistic and hope for a happy outcome (even though she is 10) although I don't want to be naive either -- I know many pets that have not made it to their 10th birthday.
I guess we'll continue to take this day by day.
Thank you all for you're kind words and advice!