Basophilia was present in this dog with presumptive essential thrombocythemia (chronic platelet leukemia). The dog had a persistent thrombocytosis (>2 million/uL) over several years with no identifiable cause and eventually died of old age. The dog had a concurrent mild non-regenerative normocytic and normochromic anemia and a persistent mild basophilia (< 5,000/uL). Several basophils with a single neutrophil (arrow) are seen in this image, along with many platelets, some of which are clumped (Wright's stain).
