Hormonal abnormalities in Pomeranians with normal coat and in Pomeranians with growth hormone-responsive dermatosis

Abstract

Summary Clinical status, skin biopsy specimens, and endocrine function were evaluated in normal-coated Pomeranians (n = 12) and Pomeranians affected with growth hormone (gh)-responsive dermatosis (n = 7), then were compared with values in mixed-breed dog controls (n = 19). All Pomeranians were clinically normal; however, the Pomeranians with gh-responsive dermatosis had bilateral alopecia and hyperpigmentation of the trunk, caudal portion of the thighs, and ventral neck region. Skin biopsy specimens from the affected Pomeranians had decreased-to-normal epidermal thickness and follicular atrophy, compared with normal-coated Pomeranians. Numerous elastin fibers were observed in the skin biopsy specimens of unaffected and affected Pomeranians. Both groups of Pomeranians had normal results of thyrotropin-releasing hormone (trh) and thyrotropin (tsh) response, adrenocorticotropin (acth) stimulation, and dexamethasone suppression testing. There was no significant increase in serum gh concentration in either group of Pomeranians after xylazine or human GH-releasing factor (ghrf) administration, whereas control dogs had significant (P ≤ 0.05) increase in serum gh concentration after administration of either agent. Baseline plasma acth concentration in unaffected and affected Pomeranians was increased above the normal range (40 to 90 pg/ml). Post-acth administration serum progesterone, 17-hydroxyprogesterone, and androgen (dehydroepiandrosterone sulfate or androstenedione) concentrations were consistently high in unaffected and affected Pomeranians, compared with values in control dogs. High baseline plasma acth concentration and increased production of progesterone, 17-hydroxyprogesterone, and dehydroepiandrosterone sulfate or androstenedione after acth administration suggested disregulation of adrenocortical hormone synthesis in both groups of Pomeranians, possibly attributable to partial deficiency of the 21-hydroxylase enzyme. Although all 3 treated dogs developed normal coat in response to supplementation with human gh, gh-responsive dermatosis in Pomeranians may not be entirely attributable to hyposomatotropism, but may also involve adrenocortical hyperprogestinism and/or hyperandrogenism.