Effects of benign prostatic hyperplasia and finasteride therapy on prostatic blood flow in dogs

Highlights

• Dogs with BPH had both high prostatic volume and vascularization score.

• There is a positive effect of finasteride in reducing prostatic vascularization.

• There is a higher prostatic artery end diastolic velocity (EDV) and lower peak systolic:diastolic velocity (S/D) in BPH dogs.

• EDV and S/D can be used to follow up the course of therapy.

• Finasteride treatment reduces simultaneously the volume, local vascularization and blood flow of the prostate.

Abstract

Benign prostatic hyperplasia (BPH) is characterized by an enlargement of the prostate accompanied by an increase in prostatic blood perfusion and vascularization. The most indicated treatment is to perform orchiectomy, however, medical treatment with finasteride can be an option for breeding dogs or elderly animals with a critical health status. In dogs, the influence of medical treatment on prostatic hemodynamics is still unknown. Therefore, this study aimed to evaluate the effects of benign prostatic hyperplasia and finasteride therapy on hemodynamic and vascular features of the canine prostate. For this purpose, twenty dogs of different breeds, body weights (10–30 kg) and ages (5–13 years) were used, assigned for: Healthy-non treated group (n = 5), BPH-non treated group (n = 5), Healthy-finasteride treated group (n = 5) and BPH-finasteride treated group (n = 5). Dogs that presented hematospermia and at least one general clinical sign (tenesmus, hematuria or dysuria) were presumptively diagnosed with BPH. Dogs were evaluated ultrasonographycally by B-mode and Doppler of the prostatic artery in a monthly interval (day 0, 30 and 60) in order to measure prostate volume (PV), expected prostate volume (EPV), prostate vascularization score (scored as minimum, intermediary and maximum) and prostatic artery blood flow parameters with the use of spectral and color Doppler ultrasound. It was possible to observe a decrease in prostate vascularization score between Day 0 (intermediary degree) and 60 (minimum degree) in finasteride treated dogs. Moreover, non-treated dogs had higher score of vascularization at Day 60 compared to animals treated with finasteride, regardless of BPH diagnosis. Healthy-non treated animals presented higher peak systolic:diastolic velocity (S/D) than BPH-non treated dogs. Furthermore, BPH-non treated dogs had lower S/D than BPH-finasteride treated dogs. In 30 and 60 days, no difference on PV was observed between BPH-finasteride treated group and Healthy-non treated group. At day 60, no difference between PV and EPV was observed for the BPH-finasteride treated group. In conclusion, finasteride treatment reduces simultaneously the volume, local vascularization and blood flow of the prostate, thus, being considered an effective and additional choice of therapy for BPH. Moreover, the course of therapy in dogs can be followed by analyzing changes in prostatic artery.

Introduction

Senility and diseases of aged dogs have ascended as research areas in veterinary medicine since the number of geriatric patients has increased in the last decades [1]. Benign prostatic hyperplasia (BPH) is a condition of high incidence in uncastrated male dogs over 5 years of age [2], making the dog an ideal model of study of the disease in men [3]. The main cause of BPH is an abnormal conversion of testosterone into dihydrotestosterone by the 5-alpha reductase enzyme, which increases the size and number of prostate cells [4], concomitantly to an enhance in local angiogenesis [5].

The diagnosis of BPH can be achieved through several prostatic evaluations. The presence of peculiar clinical signs (tenesmus, dysuria, hematuria and hematospermia [6]) and prostate transretal palpation may suggest the diagnosis of BPH [7]. Abdominal ultrasonography provides important information regarding prostate size (as the enlarged gland is abdominally positioned and can be easily visualized), essential for the presumptive diagnosis [8]. However, only prostate histological evaluation can provide the BPH definitive diagnosis [9]. Thus, prostate Doppler ultrasonography appears to be a non-invasive alternative for BPH diagnosis, through the blood flow analysis of prostatic artery, which is characterized by a narrow and acute systolic peak and low diastolic flow in normal condition [[9], [10], [11], [12]]. In BPH dogs, there is an increase in prostatic blood perfusion, identified by higher velocities in systolic and diastolic peaks, prostatic volume and high vascularization (by color flow Doppler analysis) [7,9].

The most indicated treatment for BPH aims to avoid the androgenic hormonal imbalance by performing orchiectomy, which can reduce the prostate volume in about 70% the original size in dogs [13]. However, such surgical approach is not an option for breeding dogs or elderly animals with a critical health status [14]. Therefore, a possibility of choice is to prescribe medical therapies by the use of antiandrogenic drugs, such as progestin or GnRH analogues. Although such medications reduce testosterone concentration [15,16] and have a positive effect in reducing prostate size, there is a direct interference in testicular sperm production, epididymal maturation and consequently, reducing fertility [17,18]. Thus, BPH therapy with finasteride is an alternative for an overall decrease in prostate volume [14] through 5α-reductase enzyme inhibition, reducing clinical signs without altering dog seminal quality [19,20]. Despite this clinical importance of finasteride treatment on prostatic volume reduction of BPH [14,21], no information is available of its effect on prostatic vascularization and hemodynamics in dogs and men.

In this context, this study aimed to evaluate the effects of benign prostatic hyperplasia and finasteride therapy on hemodynamic and vascular features of the canine prostate.