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.
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
PetMD. 2014. Pelger-Huet Anomaly in Dogs. http://www.petmd.com/dog/conditions/cardiovascular/c_dg_pelger_huet_anomaly#
Sharp, C.A. 2013. Pelger Huet Anomaly: Aussie Genetics Fact Sheet. Australian Shepherd Club of America. http://www.asca.org/education/health/pelgerhuetanomaly
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 http://vdi.sagepub.com/content/23/4/863.full
Fitzgibbon, Hazel. 2011. Pelger-Huet Anomaly. Samoyed Club of America Education and Research Foundation. http://www.samoyedhealthfoundation.org/diseases/pelger-huet-anomaly
Australian Shepherd Health and Genetics Institute. 2013. Pelger Huet Anomaly. http://www.ashgi.org/home-page/genetics-info/heart-and-blood/pelger-huet-anomaly
Dog DNA. 2014. Australian Shepherd. http://www.dog-dna.com/breeds/Australian-Shepherd.php