Comparison of the effects of chlormadinone acetate‐pellet implantation and orchidectomy on benign prostatic hypertrophy in the dog

Abstract

Summary Five beagles out of 11 dogs aged 7–10 years with benign prostatic hypertrophy (BPH) were implanted subcutaneously with pellets of the synthetic anti‐androgen chlormadinone acetate (CMA) at a dose of 10 mg/kg bodyweight. The remaining six dogs (one beagle and five mongrel dogs) underwent bilateral orchidectomy. Changes in prostatic volume, histological findings in the prostate and the testis, and peripheral plasma levels of LH, testosterone and oestradiol‐17β (E2) were assessed up until 24 and 4 weeks after CMA‐implantation and orchidectomy, respectively. Measurements of the size of the prostate and biopsies of the prostate were performed by laparotomy. Mean prostatic volume had decreased to 71% and 41%, respectively, of its pretreatment volume, by 4 weeks after CMA‐implantation and orchidectomy, and was 49% and 47%, respectively, of pretreatment volume at 12 and 24 weeks after CMA‐implantation. The clinical signs of BPH, e.g. haematuria, resolved within 2 weeks after either treatment. When the prostate was examined histologically 4 weeks after either treatment, hardly any evidence of active secretion (e.g. glandular epithelium projecting markedly into the lumen), was observed in CMA‐implanted dogs, alveolar diameter and height of the glandular epithelium had decreased markedly and the glandular lumen had become very small in the orchidectomized dogs. By 12 weeks after CMA‐implantation, degenerative and atrophic glands were observed in the prostate nearly the same as at 4 weeks after orchidectomy. In the testis the number of germ cells in the seminiferous tubules decreased markedly after CMA‐implantation. The mean level of plasma LH at 4 weeks after orchidectomy had increased to 14.9 ng/ml, twice the value before operation. The mean levels of plasma testosterone and E2 at 4 weeks after CMA‐implantation had decreased to 0.7 ng/ml and 9 pg/ml from 1.5 ng/ml and 15 pg/ml, the values before treatment, respectively. CMA‐implantation resulted in poor semen quality. The results indicate that CMA‐implantation at a dose of 10 mg/kg results in the same prostate‐shrinking effect as orchidectomy.

Chlormadinone acetate pellet implantation plus short‐term oral administration in dogs with benign prostatic hypertrophy

“…We have reported previously that the clinical signs of BPH in dogs resolve within 2 weeks of single CMA‐pellet implantation at a dose of 10 mg/kg, and that mean prostatic volume decreases to 70% of pretreatment volume by 4 weeks after that ( Kawakami et al ., 1995 ). In the present study, however, pellet implantation plus 7‐day oral administration with CMA resulted in disappearance of the clinical signs and marked reduction of prostatic volume within 1 week of treatment.…”

“…The pellets were 30 mm long, 5 mm wide cylinders containing 100 mg CMA each and silicone as the carrier. Although the CMA‐pellet is usually implanted to prevent oestrus in the bitch under local anaesthesia, all eight beagles were subcutaneously implanted under halothane anaesthesia between the right and left scapule with CMA pellets cut to provide a dose of 10 mg/kg (body weight), as described previously ( Kawakami et al ., 1995 ). Then laparotomy was performed as described below.…”

“…Treatment with CMA orally or by injection requires repeated dosing, however, because relapses of BPH occur therapy is discontinued ( Brass et al ., 1971 ; Kawakami et al ., 1993 ). We have reported that subcutaneous CMA‐pellet implantation is a simple and effective treatment for canine BPH ( Kawakami et al ., 1995 ). In order to achieve a more rapid prostate‐shrinking effect and resolution of the clinical signs of BPH, in this study we combined CMA pellet‐implantation with short‐term oral administration.…”