THE REQUIREMENT OF THE TESTIS IN ESTABLISHING THE SENSITIVITY OF THE CANINE PROSTATE TO DEVELOP BENIGN PROSTATIC HYPERPLASIA

A long-term study on the requirement of the testis in establishing the sensitivity of the canine prostate to develop benign prostatic hyperplasia (BPH) was conducted using 23 aging beagles both with and without their testes. The dogs had received long-term restoration of testosterone and estrogen through silicone implants. When young beagles (0.5 to 1 year of age) were castrated and normal serum testosterone and estrogen levels restored during aging to 5 years, only 50% of these dogs developed BPH in the absence of their testes as opposed to 100% BPH development in intact controls. In addition, two-thirds of the prostates in the treated groups were remarkably reduced in size, being smaller than any prostate observed in the intact controls. If, following castration, the steroid restoration was withheld for 4 years during aging and subsequently administered starting at 5 years of age and continuing for a 6-month period, none of the animals developed complex BPH. Moreover, two-thirds of the prostate glands were reduced in size by more than 60% and were atrophied in spite of the maintenance of normal prostatic tissue dihydrotestosterone levels. Regardless of the time of steroid restoration to a castrate beagle, the periurethral zone of the canine prostate exhibits various degrees of atrophy indicating functional regions within the canine prostate that are sensitive to the requirements of the testes during aging. This study implicates the importance of the testis in increasing the probability and/or sensitivity for the full development of canine BPH.