1) adrenal gland tumor(s) overproducing estrogens which is causing
   estrogen toxicity to the bone marrow and the anemia.
2) an ovarian remment that is overproducing estrogen which is causing
   estrogen toxicity to the bone marrow and the anemia.
 
Adrenal gland disease is the most likely of the two.  The fever spikes
might be from the part of the uterus that was left after the spay surgery
("stump") and it is becoming infected ("stump pyometra").  Either way it
is time to do surgery to remove the adrenal gland(s) or ovarian remment to
solve the problem.  With her anemia a blood transfusion may be needed.
Another possible option is to use Lupron to stop the stimulation the
adrenal gland or ovarian remment and control the problem with Lupron and
antibiotics untill her pcv goes up then do surgery or keep her on Lupron
long term.
 
Hope that helps,
Jerry Murray, DVM
[Posted in FML issue 3680]