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Pelger-Huët Anomaly in Cats

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Pelger-Huët anomaly is an inherited disorder in which the neutrophils become hyposegmented (i.e., the nucleus of the cells has only two lobes or no lobes at all). For the most part, this is a harmless disorder which affects domestic shorthair cats.


Symptoms and Types


There are two types of this benign defect: heterozygous and homozygous. The heterozygous version is more common and is recognized because the cat's mature neutrophils resemble bands (slightly immature neutrophils) and metamyelocytes (a predecessor of granular leukocytes). Heterozygous anomaly is not associated with immunodeficiency, with predisposition to infection, or with abnormalities of leukocyte (white blood cell) function. Conversely, the homozygous anomaly is usually lethal in utero. Cats that survive may have leukocytes with round to oval nuclei on a stained blood smear. 


Skeletal abnormalities and abnormal development of cartilage were reported in one stillborn homozygous kitten; however, a direct link with Pelger-Huët anomaly has not been conclusively confirmed.




Limited breeding studies may suggest autosomal (non-sex linked) dominant transmission of the anomaly in cats.




In most cases, veterinarians discover the anomaly in your cat by accident while conducting routine blood tests. On a stained blood smear, nuclear hyposegmentation of neutrophils, eosinophils, basophils, and monocytes will be visible, whereby the nucleus of the cells has only two lobes or no lobes at all. The hereditary nature of disease is revealed by examination of blood smears from parents and siblings.




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