Necrotizing enterocolitis can be caused by polycythemic hyperviscosity in the newborn dog

Although necrotizing enterocolitis has been associated with polycythemia in human infants, a causal relationship has not been established. Forty-six unanesthetized puppies were studied (age 6 to 14 days). Normovolemic polycythemia (Hct 0.70) was induced in 19 pups by exchange transfusion with 75 ml/kg packed red blood cells. Hypervolemic polycythemia (Hct 0.70) was induced in 14 pups by transfusion with 50 ml/kg RBC. Thirteen pups received exchange transfusion with whole blood and served as controls (Hct 0.40). Gross autopsy was performed on all pups 24 hours after transfusion or at death. Necrotizing enterocolitis was defined as areas of violaceous discoloration of the bowel associated with blood in the intestinal lumen. Although lesions appeared throughout the bowel in some pups, involvement of the distal small bowel was most common. Diagnosis was confirmed by microscopic examination. Both gross and microscopic lesions appeared similar to those in necrotizing enterocolitis in human infants. The disorder was seen in 11 of 19 pups with normovolemic polycythemia, eight of 14 pups with hypervolemic polycythemia, and only one of 13 control animals (P less than 0.01). Polycythemia can cause necrotizing enterocolitis in the newborn dog.