Pituitary dwarfism in 4 German Shepherd dogs.

Pituitary dwarfism in German shepherd dogs is an autosomal, recessive inherited disorder cha-racterized by underdevelopment of the pituitary and a deficiency of growth hormone, thyrotro-pin, prolactin, and the gonadotropins, but unaffected corticotropin secretion. Probably, a muta-tion of a gene encoding a transcription factor that precludes effective expansion of pituitary stem cells after differentiation of the corticotropic cells is the cause of this disorder. Identifica-tion of the mutation would enable the development of a DNA test for potential breeding animals and could lead to the eradication of this condition. The main clinical manifestations of pituitary dwarfism are proportionate growth retardation and alopecia. Definite diagnosis should ideally rely on the results of a combined pituitary anterior lobe function test. Although the prognosis improves significantly when dwarfs are properly treated with levo-thyroxine and either porcine growth hormone or progestins, the prognosis remains guarded.