Hi Ann,
There are a number of possibilities here. I guess I'd start with Xue Fu Zhu Yu Tang, given the purple tongue and weak pulses. It will have a bone marrow stimulating effect, which is often needed to complete recovery. It also moves circulation to the periphery, moving blood away from the body core (even the liver and spleen) to reduce sequestration and phagocytosis. If the spleen is enlarged, I'd add in (or use instead) Xiao Chai Hu Tang (Minor Bupleurum). It has an anti-mitogenic effect on the spleen lymphocytes and helps shrink the spleen, allowing erythrocytes sequestered there to be released into circulation.
That would be a good start. If the cat has other issues, we can re-evaluate. But otherwise, that's where I'd start. XFZYT is available as Mansion of Blood from Kan. You can use Open the Liver Canals as your Bupleurum. Don't use human combinations of Minor Bupleurum. They don't work as well.
Hope that helps. I look forward to hearing more data as you have it.
Steve