Superoxide dismutase (SOD) has a key role in protecting1 cells from Reactive Oxygen Species (ROS). Cancer cells produce more ROS involved in proliferation and survival of cancer cells. We, therefore, investigated the percentage of castrated dogs with Prostatic Adenocarcinoma (PA) and the relation between the occurrence of PA in the dog and the prostatic SOD activity after castration. Between 2005 and 2012, diagnosis of Prostatic Adenocarcinoma (PA) was made in 24 dogs at the Veterinary Teaching Hospital of Nippon Veterinary and Life Science University. The percentage of castrated dogs in the 24 dogs with PA and the relation between the occurrence of PA in the dog and the prostatic superoxide dismutase (SOD) activity after castration were examined. Prostatic parenchyma specimens were collected from 6 healthy dogs just before castration and 6 months after castration to measure prostatic SOD activity with a SOD assay kit. Nineteen (79.2%) of the 24 dogs diagnosed with PA had been castrated at 1-6 (2.7±1.7) years of age. Their prostatic SOD activity was significantly lower after castration than before castration (p&lt
0.01). The results of this study indicated that castration could not prevent PA from occurring and the reduction of prostatic SOD activity after castration might lead to oncogenesis in PA of the dog. © 2014 Academic Journals Inc.