ERYTHROLEUKEMIA IN 2 CATS NATURALLY INFECTED WITH FELINE LEUKEMIA-VIRUS IN THE SAME HOUSEHOLD

Erythroleukemia was observed in two unrelated cats infected with felin e leukemia virus (FeLV) from the same household. Case 1, a 1-year-old neutered male cat developed erythroleukemia (M6) after a diagnosis of myelodysplastic syndrome (MDS-Er) on the criteria of FAB classificatio n of acute leukemias. Case 2, a 1-year-old neutered female cat, which had close contact with Case 1, also developed erythroleukemia (M6Er). In both cases, marked proliferation of erythroid progenitor cells with disproportionally large numbers of immature forms was observed in the bone marrow. In Case 1, neoplastic proliferation of myeloid cells in the bone marrow was also noted at the terminal stage. Combination chem otherapy with daunomycin was partially effective for treatment of thes e erythroid neoplasias, but did not induce complete remission. Souther n blot analysis using exogenous FeLV-specific probes indicated the clo nal origin of these hematopoietic tumor cells. Furthermore, the erythr oid and myeloid tumor cells in Case 1 were shown to be derived from in dependent transformed crones. A variant FeLV was shown to be integrate d into the tumor cells in Case 1, while a full-length FeLV was found i n both cases. Because these erythroid neoplastic diseases occurred in two unrelated cats kept in the same household and these diseases are r are, they may both have been associated with the same FeLV strain.