Pharmacological and Toxicological Effects of Chronic Porcine Growth Hormone Administration in Dogs

The purpose of this study was to evaluate the pharmacological and toxicological effects of exogenous GH administration in normal adult dogs. Because porcine GH (pGH) is structurally identical to canine GH, pGH was selected for a 14-wk study in dogs. Thirty-two dogs (<2 yr) were randomized to 4 groups (4 dogs/sex/group); 1 group was treated with the vehicle and 3 groups received pGH at 0.025. 0.1, or 1.0 IU/kg/day subcutaneously. Daily clinical signs and weekly body weights were recorded. Hematology, serum biochemistry, urinalyses, electrocardiograms, and ophthalmoscopic examinations were done. Serum GH, insulin-like growth factor-1 (IGF-1), insulin, thyroxine (T4), triiodothyronine (T3), and Cortisol levels were determined. Necropsies were performed, organs weighed, and tissues were fixed and processed for light microscopic examination. Porcine GH caused increased body weight gain (p ≤ 0.05) through the mid dose; the mean weight gains at study termination in mid- and high-dose groups were 2.8 kg and 4.7 k...