Feline myeloproliferative disease. Changing manifestations in the peripheral blood.

A 4 1/2-year-old cat had myeloproliferative disease characterized by severe anemia. Peripheral blood had a profusion of relatively normal-appearing nucleated erythroid cells in all stages of development and a few primitive cells with nucleoli. The term "erythremic myelosis" best described the appearance of the peripheral blood. Two weeks later, the peripheral blood picture was that of regenerative anemia. During the next 2 months the cat made an apparent clinical recovery without treatment, but relapsed 3 months after the initial examination. One-fourth of the cells in circulation at the time of relapse contained nucleoli and appeared identical to those described in reticuloendotheliosis in cats. This transition suggested the progressive development of a greater degree of immaturity of erythroid precusors with time. The use of the term "reticuloendotheliosis" in conjunction with feline myeloproliferative disease was considered and determined inappropriate.