Pituitary dwarfism in German shepherd dogs is due to an autosomal, recessively inherited disorder. Common clinical manifestations are marked growth retardation, retention of secondary hairs (puppy coat) with concurrent lack of primary or guard hairs, and bilateral symmetrical alopecia. Pituitary dwarfism is characterized by underdevelopment of the pituitary gland and combined pituitary hormone deficiency including deficient secretion of growth hormone, thyroid stimulating hormone, prolactin and gonadotropins. In contrast, the secretion of corticotropins is unaffected.

The recessively inherited defect was localised by a genome wide approach, using microsatellite markers, to a region on chromosome 9 with a lod score of 9.8. The region contains LHX3, which encodes for a transcription factor essential for pituitary development. The dwarfism appeared to be associated with an intron deletion of a repetition from a reiterated DNA sequence. We suggest that the deletion is directly responsible for the pituitary dwarfism.

Based on the finding of the mutation, a genetic test was developed that allows identification of carriers of pituitary dwarfism in German shepherd dogs. The use of this genetic test opens the possibility to eradicate pituitary dwarfism in German shepherd dogs.