Case Description: A three year old male castrated domestic longhair cat was evaluated for lethargy and pallor. Clinical Findings: A severe normocytic, normochromic, nonregenerative anemia with a normal leukogram and platelet count was identified. Biochemical profile showed mild elevations in aspartate and alanine aminotransferases and hyperferremia. Testing was negative for feline leukemia virus, feline immunodeficiency virus, and Mycoplasma hemofelis. Bone marrow aspirate cytology disclosed erythroid aplasia and a mild plasmacytosis.
Treatment and Outcome: Prednisolone was administered at a dose of 2.4 mg/kg/day PO and chlorambucil was administered at 0.3 mg/kg PO EOD. Doxycycline was given at 4 mg/kg PO BID for 28 days. The patient received three units of packed RBCs in an 11 day period, and a regenerative response was seen on complete blood count after 16 days of immunosuppressive therapy. The dose of prednisolone was gradually tapered to 0.6 mg/kg PO SID over a period of three months. No relapse of anemia had occurred at the time of publication. Clinical Relevance: Pure red cell aplasia is a rare syndrome in cats characterized by a severe nonregenerative anemia and an absence of erythroid cells in bone marrow. The rapid response to immunosuppressive therapy supports an immune-mediated pathogenesis, although the exact mechanism of disease is unknown at this time. This condition requires aggressive and prolonged treatment with immunosuppressive drugs.