Ejaculation effect on blood testosterone and prostatic pulsed-wave Doppler ultrasound in dogs

Local vessels ultrasonography evaluates prostatic physio-pathologic states. Testosterone promotes tissue and vascular growth. Knowing variables on prostatic vasculature is crucial to correctly apply Pulsed-Wave exam. The study aims to assess how ejaculation and blood testosterone affect Pulsed-Wave indexes. Serial blood testosterone dosages and Pulsed-Wave exams were performed in 20 dogs, immediately before (T0) and after (T1) ejaculation and 6 hr later (T2). Arteria prostatica cranialis, Arteriola capsularis, Arteriola trabecularis and Arteriola parenchimalis were evaluated and mean Pulsatility and Resistivity Index, Systolic-Peak, End-Diastolic and Mean Velocity calculated. Data were grouped by time and vessel (ANOVA, p ≤ 0.05). At T1, Resistivity Index significantly lowered in A. prostatica cranialis, A. trabecularis and A. parenchimalis but grew in A. capsularis; Pulsatility Index had the same pattern, but not significant in A. parenchimalis; Systolic Peak Velocity, End-Diastolic Velocity, Mean Velocity significantly rose in A. capsularis and A. trabecularis. No indexes differed at T0 and T2. Testosterone did not differ at T0 (10.93 ± 7.05 ng/ml), T1 (12.71 ± 7.29) and T2 (10.54 ± 6.63). Results stated the risen prostatic vascular flow postejaculation, affecting Pulsed-Wave. Due to semi-rigid capsule, impairing vasodilation of other vessels, only A. capsularis indexes increased. Intimal cushions of A. prostatica cranialis kept velocities fixed; A. capsularis and A. trabecularis lack of intimal cushions, thus velocities grew. In A. parenchimalis, precapillary sphincters opening allows increased flow redistribution in vasodilated parenchymal bed, keeping velocities fixed. As testosterone, not affected by ejaculation, did not peak, vascular changes are not due to testosterone itself. These physiological effects of ejaculation suggest proper sexual rest before Pulsed-Wave exam planned to explore suspected prostatic neovascularization.