Erythroleukemia in a retrovirus-negative cat.

Case Description: A 5-year-old spayed female cat was evaluated because of lethargy of 3 days' duration, acute respiratory distress, and anemia.

Clinical Findings: Physical examination revealed the cat was in good body condition but had pale mucous membranes and elevated heart and respiratory rates. Results of hematologic analysis indicated the cat had severe anemia (Hct, 0.07 L/L; reference range, 0.28 to 0.49 L/L) and marked rubricytosis (19.0 × 10(9) cells/L; reference value, 0 cells/L). Results of serologic and PCR assays for detection of FeLV and FIV and PCR assays for detection of Mycoplasma spp were negative. Cytologic evaluation of a bone marrow aspirate and histologic evaluation of a biopsy specimen revealed a predominance of rubriblasts and rubricytes with granulocytopenia. Cytologic evaluation of fine-needle aspirates of the spleen and liver also revealed numerous rubriblasts.

Treatment And Outcome: The cat received transfusions of packed RBCs, and supportive treatment was administered. Analysis of test results yielded a diagnosis of acute myeloid leukemia (erythroid subtype). Because of continued hemolysis and anemia in combination with the diagnosis of erythroleukemia (which has a poor prognosis), the cat was euthanized.

Clinical Relevance: To the authors' knowledge, erythroleukemia has only been reported in cats infected with FeLV. However, results of all diagnostic assays for FeLV were negative in the cat reported here, which suggested that erythroleukemia can develop in cats in the absence of FeLV infection.