A Heterozygote Form Of Pelger-Huet Anomaly In Dog

Background: The Pelger-Huet anomaly is a congenital alteration in segmented neutrophil, eosinophil and basophil morphology consisting of nuclear hypo-segmentation. It presents in two ways: the homozygote (very rare) presenting granulocytes with rounded nuclei and dense chromatin, where nuclei with more than two lobes are not found; and in the heterozygote form which presents leukocytes with bi-lobulated nuclei, yet leukocytes that seem immature can also be found. Diagnosis is important for preventing WBC interpretation errors. The objective of this study is to report a case of the heterozygote form of Perger-Huet anomaly in an Australian Shepherd bit.Case: A 6-year-old Australian Shepherd bitch, weighing 28 kg, was received to perform tartar cleaning at the Veterinary Hospital (HV) of the Universidade Estadual de Maringa (UEM), in Umuarama in Parana State. In the anamnesis, the owner reported that the animal was healthy, vaccinated, and had not made use of medications recently. Upon physical examination, the animal was overweight, with adequate hydration, alert consciousness level, no exo-parasites present, rectal temperature of 39.3 degrees C (37.5 to 39.2), heart rate of 96 beats per min (60 to 120 beats per min), breathing (18 to 36 movements per min), a two second capillary perfusion time, strong and regular pulse, hyperemic oral mucosa, and otherwise, a normal-colored and popliteal reactive left lymph. Semiological evaluation presented no alteration. Due to the tartar cleaning procedure, a hemogram was requested. Blood smear analysis from the first blood workup showed a large increase in the number of hypo-segmented leukocytes, with a pattern of mature chromatin, in the form of bands and meta-myelocytes, characterizing a deviation to the left, all of which did not correspond to the patient's clinical presentation. In addition, other cells in the granulocytic lineage, such as eosinophils, also presented hypo-segmentation. Since the dog was healthy, the Pelger-Huet anomaly was suspected. To confirm, the hemogram was repeated at 12 days and a bone marrow collection was performed; the same pattern of morphological alterations in leukocytes was observed both in the peripheral blood and the bone marrow, compatible with the Pelger-Huet anomaly.Discussion: In order to arrive at an APH diagnosis, hypo-segmentation of granulocytes in the blood smear must be found and compared with the clinical results that the animal presents; associating any use of medication, serious infections, myeloid leukemia, and metastatic tumors in the bone marrow that might result in acquired hypo-segmentation; also known as pseudo Pelger-Huet anomaly. It is also necessary to evaluate family members for confirmation. Diagnosis is based on persistent nuclear hypo-segmentation of granulocytes, a clinically healthy animal, absence of medication use, and analysis of the bone marrow. It was not possible to determine a hereditary origin; for not having access to the animal's family, but earlier studies have shown that the incidence of this anomaly is high in the Australian Shepherd race. Generally, the Perger-Huet anomaly is a hematological finding that must be differentiated from other forms of hypo-segmentation. Because of its hereditary origin, it is appropriate that the owner limits the animal's reproductive interactions to avoid the risk of offspring inheriting the homozygote, which leads to death. The clinical pathologist should be aware of the patient's history to diagnose and differentiate true from pseudo Pelger-Huet anomaly. Direct blood smear microscopy is essential, because automated hematological analysis alone will not detect such changes.