Pelger-Huet Anomaly

in Australian Sheperds

What is the Pelger-Huet Anomaly?

This anomaly is an inherited disorder characterized by the hyposegmentation of neutrophils where the nucleus of those cells has two lobes or none at all. There are two types of the defect, homozygous or heterozygous.

This anomaly has been seen in humans, mice, rats, short haired cats, and some breeds of dogs such as Samoyed and Australian Shepherds.

How is the disorder transferred?

Some studies suggest that this anomaly is inherited through autosomal dominant transmission in dogs. But in Australian Shepherds specifically, there seems to be an autosomal transmission with incomplete dominance.

An example of incomplete dominance is given to the side with one white sire and one brown sire make a roan progeny.

Differences between the two types of defects

The homozygous anomaly is the rare type of the anomaly. Individuals seen with this are stillborn. If however they are born alive, they seem to have skeletal abnormalities.

The heterozygous anomaly is the more common type seen of this anomaly. These individuals are almost always healthy. There is immunodeficiency or predisposition to illness if they do carry a recessive allele to this disorder. The only way to see if they have the recessive allele is by taking a blood test to see if the neutrophils resemble bands and are not completely normal.

Example of Neutrophils in Heterzygous Individuals

Here shows what the nucleus of neutrophil cells look like when they have the anomaly.


The anomaly seems to stem from the Lamin B receptor gene, which codes for a protein in the nuclear membrane. However, scientists have yet to discover the root of the problem in dogs.


There is no current treatment for this anomaly but it can be mistaken for infection or early stage leukemia so a simple blood test can rule those out.

Why is it a problem?

This genetic disorder is a problem more for breeders than for the dogs themselves. Breeders that don't screen for this disorder or use a small breeding pool are at a higher risk of having puppies that carry or contract this disorder. This leaves litters being small and having stillborn puppies at birth. Heterozygous phenotype in dogs are relatively healthy.

Controlling this Anomaly

Other than not inbreeding dogs and using small breeding pools, breeders should have individuals suspected of being a carrier for PHA or has a close relative that is a carrier for PHA tested to make sure not to breed to another carrier.


I personally believe that every breeder must screen for this genetic disorder to try and eliminate it from the breeding pools. What other options are there that could help eliminate this genetic disorder?


PetMD. 2014. Pelger-Huet Anomaly in Dogs.

Sharp, C.A. 2013. Pelger Huet Anomaly: Aussie Genetics Fact Sheet. Australian Shepherd Club of America.

Vale, Andre M., L.R. Tomaz, R.S. Sousa, B. Soto-Blanco. 2011. Pelger-Huët anomaly in two related mixed-breed dogs. Journal of Veterinary Diagnostic Investigation vol. 23 no. 4 863-865

Fitzgibbon, Hazel. 2011. Pelger-Huet Anomaly. Samoyed Club of America Education and Research Foundation.

Australian Shepherd Health and Genetics Institute. 2013. Pelger Huet Anomaly.

Dog DNA. 2014. Australian Shepherd.