Objective: To determine the effect of finasteride at dosages of 0, 10, 0.25, and 0.50 mg/kg of body weight, PO, q 24 h, for 7 days) in a Latin square design with repeated measures. Blood was obtained before and on days 1, 2, 4, and 7 of treatment; 3 blood samples were obtained at 20 minute intervals to detect pulsatile secretion of DHT and T. Dogs were untreated at least 2 weeks between treatments.
Results: Finasteride at all doses was associated with a mean decrease in concentration of DHT of 55% (range, 155 +/- 32.3 pg/ml to 70 +/- 15 pg/ml), but had no effect on concentration of T (before treatment, 2.6 +/- 0.38 ng/ml; after treatment, 2.2 +/- 0.63 ng/ml).
Conclusions: Finasteride at these doses significantly decreased serum concentration of DHT in sexually intact adult male dogs. Concentrations of DHT and T before and 7 days after treatment did not differ by dosage of finasteride administered.
Clinical relevance: Finasteride (5 mg; 1 tablet) may be a drug of choice for treatment of benign prostatic hypertrophy in 10- to 50-kg dogs.