Clinical Efficacy of the GnRH Agonist (Deslorelin) in Dogs Affected by Benign Prostatic Hyperplasia and Evaluation of Prostatic Blood Flow by Doppler Ultrasound A Polisca 1 , R Orlandi 1 , A Troisi 1 , G Brecchia 2 , M Zerani 3 , C Boiti 2 and R Zelli 1 1 Dipartimento di Patologia, Diagnostica e Clinica Veterinaria, Sezione di Ostetricia e Ginecologia, Facolt  a di Medicina Veterinaria, Universit  a degli Studi di Perugia, Perugia, Italy; 2 Dipartimento di Scienze Biopatologiche ed Igiene delle Produzioni Animali e Alimentari, Facolt  a di Medicina Veterinaria, Universit  a degli Studi di Perugia, Perugia, Italy; 3 Scuola di Scienze mediche veterinarie, Universit  a di Camerino, Camerino, Italy Contents In six German Shepherds dogs, GnRH agonist implants (Deslorelin) were inserted subcutaneously one month after histological confirmation of benign prostatic hyperplasia (BPH). Prostatic volume (PV), characteristics of ejaculate, serum testosterone concentrations and Doppler parameters of prostatic and subcapsular arteries were detected at different time intervals, for 6 month. The prostatic volume showed a significantly reduction starting at day 37. The decrease in sperm concentration, motility and increase in morphological abnormal sperm were observed from day 22 to day 37, when it was no longer possible to obtain the ejaculate. The values of peak systolic velocity and end-diastolic velocity in prostatic and subcapsular arteries showed from day 11 a gradual decrease, significant at day 22 until day 37 and reaching the lowest values at day 52 until the end of observation. The power Doppler pixel intensity of both arteries showed a gradual decrease from day 5 until day 52. In particular, a significant decrease was observed for both arteries from day 11. Testos- terone serum concentration decreased to undetectable levels by day 11 until the end of the observations. All these Doppler parameters and testosterone values were positively correlated with the prostatic volume. Furthermore, testosterone values were positively correlated with peak systolic velocity, end diastolic velocity and pixel numbers. The use of implants containing GnRH analogues, even in asymptomatic subjects, is effective for the control of BPH and the application of Doppler exam of prostatic blood flow represent an non-invasive tool for monitoring the response of medical treatment. Introduction In dogs, the prostatic gland, in analogy to humans, presents an age-related propensity to develop benign prostatic hyperplasia (BPH) (Leav et al. 2001), charac- terized by an increase in the number (hyperplasia) and volume (hypertrophy) of prostate cells (Memon 2007). The exact pathogenesis of this condition is not com- pletely understood; however, the dihydrotestosterone has an important role in stimulating enlargement of the canine prostate by enhancing growth of both stromal and glandular components (Russell and Wilson 1994). Moreover, it was reported that estrogens, growth hormone, prolactin and relaxin may contribute to the development of BPH (Wennbo et al. 1997; Grayhack et al. 1998; K€ olle et al. 1999; Yoshinaka et al. 2000; Niebauer et al. 2005; Kaplan-Lefko et al. 2008). Often asymptomatic BPH is frequently diagnosed as an incidental finding during the andrological examination. Presumptive diagnosis is based on the dog’s history, physical examination, prostate fluid examination and prostate imaging (radiology and ultrasonography). A definitive diagnosis is obtained with a biopsy of the gland (Memon 2007). In many cases, treatment is not required especially if dogs are asymptomatic. The goals of treatment are to resolve the clinical signs of the condition, reduce discomfort and restore the dog pain-free quality of life. The surgical removal of the testis represents the first therapeutic choice, but recently, for ethical reasons and animal welfare legislation, restrictions have been imposed on the ‘classic approach’. The choice between surgical (orchiectomy) and conservative approach depends mainly on general health of the animal and the necessity to preserve the fertility of the subject. Different pharmacological agents are reported for the treatment of BPH such as estrogens (Olson 1984), antiandrogens (Tsutsui et al. 2001), 5a-reductase inhib- itors, (Iguer-Ouada and Verstegen 1997) and progesta- gens (Bamberg-Thalen and Linde-Forsberg 1993; England 1997). A recent option for temporary hormonal castration in male dogs relies on the down-regulation of the hypothalamus–pituitary–gonadal axis as a result of a continuous exposure to a GnRH agonist applied via a slow-release subcutaneous implant (Junaidi et al. 2009; Ludwig et al. 2009). In human medicine, many works reported the use of GnRH analogues for BPH treatment (Peters and Walsh 1987; Gabrilove et al. 1989; Gonzalez- Barcena et al.1994), but few works (Goericke-Pesch et al. 2010; Palm and Reichler 2012) reports the clinical efficacy of GnRH analogue implant (azagly-nafarelin) in dogs affected by BPH. Doppler ultrasonography, in its different application Colour Doppler (CD), pulsed wave spectral Doppler (PW) and power Doppler (PD), is used for the study of pathophysiological modifications of human prostatic glands. (Miyashita et al. 1988; Kojima et al. 1997, 2000; Keener et al. 2000; Tsuru et al. 2002). Kojima et al. (2000) demonstrated that Doppler ultrasound can discriminate between human patients with normal prostate and those with BPH. In dogs, G€ unzel-Apel et al. (2001) reported the Doppler ultrasound charac- teristics of prostate vascularization in BPH-affected dogs. Therefore, this study was carried out to: (i) increase clinical data on the efficacy of GnRH analogue implant (Suprelorin â ) in the treatment of BPH affected dogs and (ii) determine the hemodynamic changes of the prostatic blood flow by Doppler analysis during the treatment. © 2013 Blackwell Verlag GmbH Reprod Dom Anim 48, 673–680 (2013); doi: 10.1111/rda.12143 ISSN 0936–6768