Hi Kevin,
Based on your question I assume that bloodwork was normal until after CCNU. How many doses of CCNU has this dog had, do you know? How severe is the anemia and thrombocytopenia? Was there originally concern for systemic involvement (lung mets, other intra-abdominal mets). If bone marrow was normal I am wondering why they did not do splenectomy to begin with? Just because of the aggressive disease type?
These are my thoughts on the thrombocytopenia and anemia:
1) CCNU can commonly cause neutropenia and thrombocytopenia. anemia would be less common. I would usually expect neutropenia if this was from the CCNU rather than anemia. Cytoxan is relatively sparing to the bone marrow.
2) Internal bleeding would be my major concern as splenic tumors are at high risk of rupture and you would get a consumptive thrombocytopenia with that - in this case splenectomy would definitely be recommended (onbiously make sure there are no other mets in lungs or liver now before doing surgery)
3) dogs with bulky cancer can get immune mediated destruction of their red cells and platelets but being that the dog was on pred recently this is probably less likely
4) Could have bone marrow involvement, although I would rule out internal bleeding or immune mediated causes first.
XCHT seems like a good idea to me and I would definitely be thinking in that direction. - Steve might have some fancy version of XCHT that he likes better but I use a lot of XCHT.
Also, You need some kind of hemostatic formula on board. I usually have Yunnan Pai Yao on board for all my splenic tumors to minimize internal bleeding. Another idea might be Bu Yang Huan Wu Tang as it contains Astragalus which is hemostatic and Peach Pit (Tao Ren) which is an antineoplastic blood tonic (contain laetril)and also tonifies blood, moves blood and treats Damp accumulation. Although to me your choice of Dang Gui Shao Yao San makes sense. So you could just add Yunnan Pai Yao. -This is a case for Super Steve! Histiocytic Sarcomas are tough.
Here is a little conventional info in case you are looking at splenectomy and your owner would like more stats:
For localized histiocytic sarcoma of internal organs such as the spleen, prognosis with surgery alone is usually poor with a median survival time of 1 month and 0-20% 1-year survival rate. The following factors have been associated with prognosis for dogs with splenic histiocytic sarcoma: lymphoid-to-fibrohistiocytic ratio, mitotic index, and tumor grade. Dogs with a lymphoid-to-fibrohistiocytic ratio of >/= 40% had 87% 1 year survival rates compared to 55% for ratios <40%. One-year survival rate for dogs with grade I or II tumors is 60% compared to 30% for grade III tumors. The impact of chemotherapy in patients without visible evidence of disease after surgery has not been evaluated. CCNU has resulted in a 46% response rate in dogs with measurable disease. Median duration of remission for these 56 dogs was 3 months and median survival time was 3.5 months.
Hope that very long-winded conversation was of some help.
Erin