Pseudo-Pelger-Huët anomaly in a Japanese Black neonatal calf

Abstract

　Pelger-Huët（PH）anomaly is a dominant hereditary disorder of leukocyte development and is characterized by persistent nuclear hyposegmentation of granulocytes and monocytes. Acquired PH anomaly, i.e., pseudo-PH anomaly, has been reported in cattle but not in neonatal calves. A 2-day-old, male Japanese Black calf was presented with low body weight（22 kg）, anorexia, depression, astasia, hypothermia, and dehydration since birth. At the first presentation, routine hematology revealed severe anemia（RBC, 261×10⁴/μℓ; hematocrit, 7.9%）with poikilocytosis and leukocytosis（19,450/μℓ）with left shift, increased PH（36%）and band neutrophils（22%）. PH cells were not found in the blood smear of the dam. Based on these findings, pseudo-PH anomaly was diagnosed. Treatment consisted of intravenous ampicillin（0.3 g/day, 1-3 days）, fluid therapy with electrolytes, amino acids and glucose（1-8 days）, and blood transfusion（400 mℓ/day, 1-4 days）. On the fifth day of treatment, the calf was able to stand up without assistance, and the desire to suckle was restored. As the calf continued to recover, PH cells rapidly disappeared by 8 days of treatment, and improvement of anemia was seen concurrently. The observed treatment response suggests that pseudo-PHA was likely caused by an infection and myelopoiesis abnormality. To our knowledge, this is the first case of pseudo-PH anomaly in a neonatal calf.