Red cell fragmentation in the dog: an editorial review

Red blood cell fragments in blood smears from dogs are described morphologically and pathogenetically. Categories include microangiopathic fragmentation, spherocytic fragmentation, Heinz body fragmentation, metabolic fragmentation associated with systemic disease, and artifactual fragmentation. Microangiopathic fragmentation is associated with direct physical damage to normal circulating red blood cells as they pass through abnormal capillary beds. Spherocytic fragmentation is a common feature of immune-mediated hemolytic anemia and results from the removal of portions of antibody-coated erythrocyte plasma membranes by phagocytes of the reticuloendothelial system. Heinz body fragmentation occurs when rigid particles of oxidized hemoglobin are torn from affected red cells as they circulate through the spleen. Metabolic fragmentation is an ill-defined syndrome most commonly associated with cholesterol loading of red cell membranes caused by lipid metabolism abnormalities. Resulting spiculated red cells are more susceptible to traumatic disruption. All the types of red cell fragmentation described in dogs have been observed and documented in man.