A POTENTIALLY MISLEADING PRESENTATION AND COURSE OF ACUTE MYELOMONOCYTIC LEUKEMIA IN A DOG

A nine-year-old, castrated male golden retriever had lethargy, fever, massive peripheral lymphadenomegaly, hepatosplenomegaly, and pale muco us membranes. There was a marked leukocytosis (456.3x10(3) cells/mu l) with 99% blasts; a moderate, nonregenerative anemia; and marked throm bocytopenia. A tentative diagnosis of acute lymphocytic leukemia was m ade pending results of cytochemical staining. Despite the severity of the laboratory and clinical findings, the dog exhibited a partial resp onse to an induction chemotherapy protocol commonly used for lymphoma. Subsequent cytochemical staining of the original blood and bone-marro w samples resulted in a revised diagnosis of acute myelomonocytic leuk emia (AML-M4). Clinicopathological findings, response to treatment, an d clinical outcome in this case of canine AML-M4 are discussed.