Nucleated erythrocytes in blood in a case of canine plumbism. The PCV was 39%.

The presence of nucleated red cells in peripheral blood (erythroblastosis) usually signals a regenerative response by marrow to anemia, in which case it is accompanied by reticulocytosis. In some breeds of dogs, e.g. Miniature Schnauzers and Dachschunds, small numbers of nucleated red blood cells may be seen in the circulation of healthy dogs.

Occasionally, they are seen in circumstances of severe endotoxemia, in which case their presence is a result of injury to marrow causing "inappropriate" release. They are also seen in cases of acute lead intoxication, again due to marrow injury.

Circulating nRBCs can also be a feature of myelodysplastic syndromes and acute myelogenous leukemias, in which cases they are a sign of disturbed maturation and release of cells from marrow.

The cause in a given case is determined by clinical context, the overall pattern of the CBC, and the results of other laboratory tests.

Nucleated red blood cells are counted by all hematology analyzers (regardless of technique) as white blood cells. For this reason, the white blood cell count must be corrected for the number of nucleated red blood cells in the circulation. To correct a leukocyte count, the number of NRBCs per 100 leukocytes is recorded during the differential leukocyte count. Then a correction is made as follows: