B-Mode and Doppler Ultrasonographic Findings of Prostate Gland and Testes in Dogs Receiving Deslorelin Acetate or Osaterone Acetate

Abstract

This article presents B-mode and color Doppler imaging of the prostate and testes in dogs suffering from benign prostate hyperplasia (BPH), and receiving deslorelin acetate (SuprelorinTM) or osaterone acetate (YpozaneTM). The study was planned as a controlled clinical trial, dogs were divided into negative control (healthy dogs, n = 10), positive control (dogs with BPH, n = 10), and study groups, III (n = 15), receiving deslorelin acetate (DA), and IV (n = 10), receiving osaterone acetate (OA). The B-mode appearance of the prostate parenchyma improved in all investigated dogs from the DA group, and in 60% of OA dogs. Prostate volume was reduced more quickly with OA (from D14), but lasting for a shorter time (on average up to week 20), compared to DA that reduced the prostate volume more slowly (>8 weeks), but the reduction remained longer (>24 weeks). The systolic peak velocity (SPV) and mean velocity (Vmean) were higher in all dogs diagnosed with BPH, compared to Control Group I. The indices did not change in both Control Groups I and II, whereas in study Groups III and IV they decreased throughout the study period compared to day 0 and Control Group II. In Group III the highest reduction was noted from day 21 to week 8, whereas in Group IV the lowest Vmean was recorded before day 21. Testicular parenchyma and volume changed significantly in Group III receiving DA, and the velocity of blood flow in the testicular artery correlated positively with testicular volume only in this group (III). The present study proved the usefulness of B-mode and color Doppler US imaging techniques for diagnosis and progress assessment of dogs suffering from BPH. The blood flow kinetics (mainly SPV) demonstrated a time association between the blood flow changes registered in the prostatic artery, and the subsequent volumetric and sonographic improvement of the prostate parenchyma. The reduction in flow indices was noted prior to the reduction in prostate volume, suggesting that the sonographic recovery of the prostate tissue, occurs secondarily to the regression of the prostate vascular system. Both investigated medications (osaterone acetate and deslorelin acetate) led to a significant sonographic improvement. Deslorelin acetate reduced prostate volume more slowly, but its effect lasted longer than for osaterone acetate.

What Happens in Male Dogs after Treatment with a 4.7 mg Deslorelin Implant? I. Flare up and Downregulation

“…Due to the loss of testicular endocrine and germinative function, testis volume was significantly reduced during treatment and testicular consistency was changed from firm-elastic to soft-elastic in TG, whereas it was not affected by time in CG. The reduction in TV by about 60% on D56 (week 8) in seven out of seven dogs in our study is in good agreement with earlier observations reporting a maximum of 65% reduction after a 3, 6 or 12 mg deslorelin SRI [ 31 ] or a 4.7 mg deslorelin SRI [ 33 ], but slightly less than the 75% reduction reported after 6 mg deslorelin SRI [ 22 ]. Similarly, the change in testicular consistency was also already described before with other implants (azagly-nafarelin, buserelin) [ 6 , 10 , 29 ].…”

“…Only two studies have investigated PV reduction following application of a 4.7 mg deslorelin SRI, however, in dogs with benign prostatic hyperplasia. The maximum reduction in PV was by 66% in various breeds [ 33 ] and 67% in German Shepherds [ 30 ], reported 24 weeks and 52 days after treatment, respectively.…”

“…Andrological examinations, including measurements of testicular dimensions and recording of testicular consistency, were performed weekly by the same blinded person (first author) to avoid operator-related variance [ 33 ]. Testicular dimensions were obtained using a sliding caliper as previously described [ 34 , 35 ].…”

“…Vickery et al were the first to describe the use of GnRH agonists for chronic contraception in dogs [ 27 , 28 ]. Afterwards, various GnRH agonist depot formulations were described in the literature to successfully suppress testicular function in male dogs, namely buserelin [ 6 , 29 ], azagly-nafarelin [ 10 ] and deslorelin [ 7 , 8 , 22 , 23 , 24 , 30 , 31 , 32 , 33 ].…”

“…Although it has been widely used since its introduction to the market in 2007 and extensive clinical experience is available, the effects on germinative and endocrine testicular function associated with its application have been poorly characterized. Only a small number of studies investigated the effects of a Suprelorin ® 4.7 mg deslorelin implant on prostatic size [ 30 , 33 ] and on semen quality [ 7 , 30 ]. More detailed information on the type and dynamics of deslorelin-induced changes in testicular functions should be considered very helpful for use in daily clinical practice, and it is important to fully advise owners of male dogs who choose deslorelin SRI as a medical alternative to castration.…”