FIP - feline infectious peritonitis
A number of conditions can cause anemia and neutropenia (low white cell count), certainly viral infections would be at the top of the diagnostic list. Feline leukemia, feline immunodeficiency virus (FIV) and feline infectious peritonitis (FIP) would be my first thoughts.
Feline panleukopenia is a parvo virus and if vaccination was done, then adequate protection should result. The definitive test for FIP is a biopsy of lymph node/ bowel/ etc.; blood titers are equivocal because they are not definitive. Unfortunately FIP is lethal once symptoms are manifest. Any illness, if chronic, can induce anemia. There is about a five percent incidence of FIP in North America; feline panleukopenia is unusual in adequately vaccinated cats.
Dr. Van Lienden
Dr. Raymond Van Lienden DVM
The Animal Clinic of Clifton
12702 Chapel Road, Clifton
Virginia, U.S.A. 20124