Induction of benign prostatic hyperplasia in intact dogs by near-physiological levels of 5α-dihydrotestosterone and 17β-estradiol

Benign prostatic hyperplasia was induced in mongrel dogs treated for 60 days with one silastic implant containing 17β‐estradiol and four containing 5α‐dihydrotestosterone. The condition was characterized by (1) a marked increase of the stromal elements, particularly the stromal septa between the individual glands, (2) a slight increase in prostatic volume, and (3) a morphology that resembled spontaneous complex benign prostatic hyperplasia in the dog. Other groups of animals that remained untreated or received only 17β‐estradiol or only 5α‐dihydrotestosterone did not develop this condition. Prostate volumes decreased by 14% in the estrogen‐treated dogs, whereas they increased in the androgen‐treated animals by 6% compared to pretreatment prostate volumes. The morphology of the epithelium of the prostates of androgen‐treated animals was not different from that of controls despite the increase in prostate volume. The serum 17β‐estradiol and 5α‐dihydrotestosterone concentrations were increased from 25 ± 2 (mean ± SEM) and 256 ± 42 pg/mL, respectively, in control dogs to 52 ± 37 and 562 ± 37 pg/mL, respectively, in the dogs treated with the hormone combination. Thus, hormone concentrations were two‐ to three‐fold higher than control values, and the ratio of estradiol‐17β to 5α‐dihydrotestosterone was increased by up to 19%. These data demonstrate that treatment of dogs with low levels of estrogen and androgen may be an excellent model for the study of spontaneous complex benign prostatic hyperplasia in aging men.