Howell-Jolly bodies in the blood of a (non-anemic) splenectomized dog. Howell-Jolly bodies (H-J) bodies are small fragments of non-functional nucleus which were not extruded as the cell left the marrow. Usually, but not always, the host red cell contains only a single HJ body, which appears as a blue, perfectly round inclusions. Occasionally, uneven staining of an H-J body can result in a ring-like appearance which may mimic a parasite.       In dogs and ruminants, these escapees are not routinely observed in peripheral blood because they are removed from the red cells by the pitting function of the sinusoidal spleen. Their numbers do increase to detectable levels in regenerative anemias in these and other species. In bovine species, they must be differentiated from Anaplasma organisms.       In normal cats and horses (non-sinusoidal spleens), and in any species with compromised or absent splenic function (corticosteroids, splenectomy), low numbers are seen in the blood of non-anemic patients. In non-anemic miniature and toy poodles with hereditary macrocytosis, increased numbers of Howell-jolly bodies (some abnormal and fragmented) may be observed.