EFFECTS OF ORAL-ADMINISTRATION OF CHLORMADINONE ACETATE ON CANINE PROSTATIC HYPERTROPHY

Seven of the 25 dogs (4 to 15 years old) with benign prostatic hypertr ophy (BPH) at the teaching hospital of Nippon Veterinary and Animal Sc ience University from 1989 through 1990 were treated orally with chlor madinone acetate (CMA), a synthetic anti-androgen, 2 mg/kg/day, twice a day for 3 or 4 weeks. Prostatic size was measured by radiography and ultrasonography before and after CMA treatment, and prostatic volume was calculated from the images. Semen quality was examined in 3 of the dogs with BPH. Peripheral blood samples were collected and plasma lev els of LH, 4-androstenedione, 5alpha-dihydrotestosterone, testosterone and estradiol-17beta were measured. Clinical signs disappeared within 10 days after the start of CMA treatment. The mean (+/-S.E.) prostati c volume 3 or 4 weeks after treatment decreased to 39 +/- 4% of the pr etreatment volume. The mean level of plasma testosterone in the dogs w ith BPH before treatment was significantly lower than that in the norm al dogs (P<0.01). In 6 of the CMA-treated dogs the levels of all hormo nes examined, except LH, were significantly lower after CMA treatment than before (P<0.05). The sperm count and motility decreased and the p ercentage of abnormal sperms increased after CMA treatment. These resu lts demonstrate that, although CMA treatment in dogs with BPH inhibits testicular function, the prostatic volume is markedly reduced and cli nical signs disappear in a short period after the therapy. However, a relapse of BPH was observed approximately 6 months after oral CMA trea tment in some dogs.