Pastor aleman4/20/2023 ![]() High growth hormone and low somatomedin values are found in Laron's syndrome in infants. We have no conclusive explanation for this, due to the present lack of knowledge of how growth is regulated. An increase in growth hormone with lowered somatomedin raises questions. Pressure atrophy of the adenohypophysis led to the loss of most of the hormone-producing tissue. Pituitary dwarfism in the 13-month-old bitch can be ascribed to the persistence of one end of the ductus craniopharyngeus, Rathke's pouch. While ACTH was lowered (ACTH less than 10 pg/ml normal 74-210 pg/ml), cortisol was normal (0.81 micrograms/100 ml normal 0.5-2.5 micrograms/100 ml). Hypothyroidism was verified by a low T4 binding value (T4 0.9 micrograms/100 ml normal 4.1 +/- 0.9 micrograms/100 ml) and a low thyroid binding index (TBI 0.54 normal 0.61 +/- 0.05). Endocrinological studies showed a surprisingly high value for serum growth hormone (cGH 4.1 ng/ml normal range 1.8-3.8 ng/ml as determined by a specific homologous radioimmunoassay) and a pathologically low serum somatomedin (SM 0.132 normal value more than 0.50 unit/ml, determined by 35S incorporation in piglet rib cartilage). The thyroid was relatively small, and histologically showed focally resting follicles without lumen. ![]() The latter had pressure atrophy, and immunohistochemically showed only remnants of the hormone-producing cells (growth hormone-GH prolactin-PRL thyrotropin-TSH luteinizing hormone-LH adrenocorticotrophin-ACTH/MSH). Grossly, the pituitary gland had small and large multiple cysts, which light microscopy showed to be exclusively within the adenohypophysis. The clinical parameters in our dog (hematology, function of liver and kidney) were normal. Two subsequent breedings from the same parents produced normal offspring. Retardation of growth was noticed when the dog was about two months old. A 13-month-old, 7-kg, dwarf purebred German shepherd bitch with alopecia and hyperpigmentation was admitted to the clinic for euthanasia. This is the first histopathological, immunohistochemical and endocrinological study. Some cases probably were caused by persistent cysts of Rathke's pouch. Pituitary dwarfism has been described in more than 20 German shepherd dogs.
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