Effects of benign prostatic hyperplasia and finasteride therapy on prostatic blood flow in dogs
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.
Section snippets
Animals and experimental study
The current study was approved by the Bioethics Committee of the School of Veterinary Medicine and Animal Science - University of São Paulo (protocol number 7122171213).
Twenty dogs, aged from 5 to 13 years, of different body weights (10–30 kg) and breeds were used (Table 1). All dogs were privately owned and for ethical reasons only dogs to which the owners desired to enter the experiment were elected. All owners signed a written informed consent prior to entering the study and were aware of
Results
No significant interaction between moment of evaluation, diagnosis of BPH and finasteride treatment was observed. However, there was a significant interaction between the diagnosis of BPH and finasteride treatment for the peak systolic:diastolic velocity (S/D) of the prostatic artery (P = 0.03). Also, a significant interaction between moments of evaluation and finasteride treatment occurred for the prostate vascularization score (P = 0.02).
It was possible to observe a decrease in prostate
Discussion
In the present research, we evaluated the effects of canine benign prostatic hyperplasia and finasteride treatment on prostate hemodynamic and vascular features, by means of a B-mode and Doppler (spectral and color) ultrasonography study.
Benign prostatic hyperplasia is a similar condition in dogs and men, being considered the disease of highest incidence among prostate disorders in adult and uncastrated dogs [[27], [28], [29]]. For treatment purpose in dogs, finasteride (a synthetic inhibitor
Conclusions
To our knowledge, this is the first study to assess Doppler ultrasonography during finasteride treatment in BPH dogs. 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 can be followed by analyzing changes in prostatic artery EDV and S/D hemodynamic parameters in dogs. Therefore, new approaches for the diagnosis
Acknowledgements
This research was financially supported by Fundação de Amparo a Pesquisa do Estado de São Paulo (FAPESP) grant no. 2015/05419-5 and 2013/25966-5.
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