PROGESTIN-INDUCED GROWTH-HORMONE (GH) PRODUCTION IN THE TREATMENT OF DOGS WITH CONGENITAL GH DEFICIENCY

The recent demonstration of the ability of progestins to induce the ex pression of the growth hormone (GH) gene in the mammary gland of dogs and cats opens possibilities for the treatment of some forms of GH def iciency with progestins. Therefore, one male and one female German she pherd dog with congenital dwarfism because of a pituitary anomaly were treated with subcutaneous injections of medroxyprogesterone acetate ( MPA) in doses of 2.5-5.0 mg per kg body weight, initially at 3-wk inte rvals and subsequently at 6-wk intervals. In both dogs, body sizes inc reased and a complete adult hair coat developed. Undesirable side-effe cts were recurrent periods of pruritic pyoderma in both dogs and cysti c endometrial hyperplasia with mucometra in the female dog. Parallel w ith the physical improvements, plasma insulin-like growth factor I con centrations rose sharply. Plasma GH concentrations tended to rise, but never exceeded the upper limit of the reference range. Nevertheless, one of the dogs developed slight acromegalic features, possibly becaus e mammary GH, unlike pituitary GH, is released evenly throughout the d ay. Even moderate increases in circulating GH concentration may, there fore, give rise to overexposure. It is concluded that long-term treatm ent with MPA can be used as an alternative for heterologous GH in the treatment of congenital GH deficiency in the dog. (C) Elsevier Science Inc. 1998.