Ok, thanks for that good info.
Autoimmune hemolytic anemia (or simply immune mediated anemia)= IMA is the most likely disease process in a female schnauzer her age.
Some of these patients become yellow (on top of pale) because of the hemoglobin released in such huge amounts from the actual breakdown of cells. The cause is thought to be something that overstimulates the immune system--this something can actually be cancer somewhere in the body, not necessarily in the bone marrow, possibly an infection, a drug reaction. Most of the time the cause is unidentified
These dogs usually have what is called a "responsive anemia"--their bone marrow is working hard to replace cells that are literally being "dissolved" within the circulation or "plucked out" by organs like the spleen. This is often why the spleen is big.
In other cases, the spleen enlarges because IT is working hard to itself pump out more red cells into circulation from where they get stored.
Dogs with an "aplastic anemia" (aplastic==not producing any new cells, but not necessarily destroying cells already in circulation) are "running out" of red blood cells as the cells age and then die off as would happen naturally after 100 days)--but they aren't replaced. Estrogen and other drugs can cause this.
Bone cancer itself (osteosarcoma) is indeed very painful. One of the most debilitating in those terms.
Bone MARROW cancer (usually leukemias which affect white cell production--overproduction-- NOT red blood cell cancers) is not painful per se.
It can take longer than 3 days for a response. She may yet require a transfusion, as many do (or another blood product).
They may advise that a bone marrow sample be collected to see just what cells are/aren't being made in there--i.e. if they are being released and being destroyed just as they are made, being made and NOT released, or not being made at all.