Pelger-Huët anomaly (PHA) is a rare, inherited blood condition in which the nuclei of several types of white blood cells (neutrophils and eosinophils) have unusual shape (bilobed or dumbbell-shaped) and structure (coarse and lumpy). It may also be called Pelger’s nuclear anomaly, or Pelger-Huët nuclear anomaly.
For the most part, this is a harmless disorder which affects several breeds of dogs, including the American foxhound, Australian shepherd, and basenji.
When only one defective copy of the gene is inherited (heterozygous), PHA can exist by itself with no detrimental effect to the dog. However, if a defective gene is inherited from each parent (homozygous), the disorder in dogs is typically lethal in utero or shortly after birth, leading to:
Lower litter sizes surviving to weaning than in normal dogs
Matings between two animals with Pelger-Huet anomaly may result in smaller litter sizes because the homozygous form of the anomaly is usually lethal in prenatal animals. In the unlikely event when affected puppies survive, they may exhibit osteochondrodysplasia (abnormal growth of cartilage) marked by severe skeletal deformities and increased susceptibility to infection.