Comparison of spontaneous and testosterone-induced benign prostatic hyperplasia in dogs

Objective To compare the advantage and disadvantage of spontaneous and testosterone-induced benign prostatic hyperplasia(BPH) in dogs,and to provide a better BPH model for evaluating BPH drugs.Methods Twelve male adult Beagle dogs were randomly divided into 2 groups,one as normal control group,the other was testosterone(T) group,and 6 old beagle dogs were selected by ultrasound detection was old dog group(Spontaneous BPH group).After the dogs of T group being castrated,all animals except the old dogs were administered testosterone 0 and 2.5 mg/(kg.d) by intramuscular injection for 4 weeks.The body weight was monitored every week,the prostate volume was measured by ultrasound detection and blood samples were collected at 24 hours before the animal were killed after the last treatment.The prostate was removed to measure the wet weight,water content,volume and to calculate the organ coefficient.Then the prostate was fixed in 10% formalin solution,embedded in paraffin,sectioned at 4 μm,and stained with hematoxylin and eosin.Slides were observed under microscope and analyzed the height of prostatic epithelium(HPE) and acinar luminal area(ALA) with a micro-image analysis system(MIVNT).T level,dihydrotestosterone(DHT) level,prostate specific antigen(PSA) level and prostate acid phosphatase(PAP) level in serum and prostate were assayed according to the instruction of magimuzyme kits and ELISA kits.Results ①After 4 weeks treatment,the mean body weight of dogs in the three groups were smoothly increased.②The ultrasound showed that the prostate volumes of animals in the T group and old dog group were significantly larger than that of the normal control group(P0.01).③The real prostate volumes of T group and old dog group were significantly larger than that of control(P0.05),and the prostate volume of the old dog group was larger than that of the T group.Compared with the control,the prostate wet weight and organ coefficient of T group and old dog group were significantly increased(P0.05),and both indexes of the old dog group were greater than that of the T group.④According to the data of histopathology,in the T group,the hyperplastic prostate showed more hyperplastic glands,especially was prostatic epithelium proliferation,while in the old dog group,the hyperplastic prostate mostly contributes to prostatic mesenchyme proliferation.Further MIVNT results showed that,compared with the control,the HPE was significantly increased(P0.01) and the ALA was significantly enlarged in the T group(P0.01),while in old dog group,the HPE was also significantly increased(P0.01) and the ALA was significantly enlarged(P0.05),but its HPE was lower than that of the T group.⑤Compared with the control,in T group,the T,DHT and PAP levels in serum were slightly increased,and T(P0.05),DHT(P0.01),PAP(P0.05) and PSA levels in prostate were significantly increased.In the old dog group,the T,DHT and PAP levels in serum were slightly increased,the T level in prostate was slightly increased,and the DHT,PAP and PSA levels in prostate were slightly decreased.Conclusion Both spontaneous and testosterone-induced BPH model in dogs can be used to evaluate BPH drugs,but there are some differences between these two groups.