Effects of finasteride on size of the prostate gland and semen quality in dogs with benign prostatic hypertrophy

Objective-To determine the effect of the 5 alpha -reductase inhibitor finas teride on prostatic diameter and volume, semen quality, and serum dihydrote stosterone (DHT) and testosterone concentrations in dogs with spontaneous b enign prostatic hypertrophy (BPH). Design-Double-blind placebo-controlled trial. Animals-9 dogs with BPH. Procedure-Five dogs were treated with finasteride for 16 weeks (0.1 to 0.5 mg/kg [0.05 to 0.23 mg/lb] of body weight, PO, q 24 h); the other 4 receive d a placebo. Prostatic diameter, measured radiographically, prostatic volum e, measured ultrasonographically. semen quality, and serum DHT and testoste rone concentrations were evaluated before and during treatment. After recei ving the placebo for 16 weeks, the 4 control dogs were treated with finaste ride for 16 weeks, and evaluations were repeated. Results-Finasteride significantly decreased prostatic diameter (mean percen tage decrease, 20%), prostatic volume (mean percentage decrease, 43%), and serum DHT concentration (mean percentage decrease, 58%). Finasteride decrea sed semen volume but did not adversely effect semen quality or serum testos terone concentration. No adverse effects were reported by owners of dogs in the study. Conclusions and Clinical Relevance-Results suggest that finasteride can be used to reduce prostatic size in dogs with BPH without adversely affecting semen quality or serum testosterone concentration.