Causes of erroneous white blood cell counts and differentiation in clinically healthy young northern elephant seals (Mirounga angustirostris)

From 1993 to 1995, approximately 10% of the clinically healthy northern ele phant seals (Mirounga angustirostris) at The Marine Mammal Center in Califo rnia exhibited a large unexplained increase in their white blood cell (WBC) count. In these animals, WBC counts ranged from 28,780 to 125,000/mm(3), w ith a mean of 50,087/mm(3). Significant correlations between the leukocytos is and weight gain and day of admittance were identified, but no correlatio n existed between leukocytosis and general state of health, sex, length of stay, or diet. Bone marrow contamination of blood samples, erroneous automa ted leukocyte counts, and leukogram changes consistent with subclinical inf lammation were the major factors contributing to me elevated WBC counts in these apparently clinically healthy animals.