Abstract
Congenital dyserythropoiesis with dyskeratosis is a slow, progressive, and often fatal disease in Polled Hereford calves. Affected calves have a macrocytic normochromic anemia with a mild reticulocytosis. Studies indicate that calves are hyperferremic with increased saturation of serum total iron binding capacity, which rules out iron deficiency as a cause. Other secondary causes of dyserythropoiesis, including cobalamin and folate deficiencies, are unlikely because serum cobalamin and folate levels of affected calves were normal. Virus isolation was negative, and failure to identify bovine retroviral antigens or antibodies from several calves suggested that viral agents were not involved. Bone marrow cytologic findings were similar to those in congenital hereditary dyserythropoiesis in humans and included occasional multinucleate cells, internuclear chromatin bridging between nuclei of partially divided cells, and, more frequently, irregular nuclear shapes and chromatin patterns. DNA content and cell cycle distribution of erythroid cells appeared normal, and no electrophoretic abnormalities were detected in erythrocyte membrane proteins. The Polled Hereford syndrome is similar in many ways to type I congenital dyserythropoiesis in humans and may be an appropriate biomedical model for studying erythroid proliferation during dyserythropoiesis.