Adenocarcinoma of the canine prostate: immunohistochemical examination for secretory antigens.

Thirty-one canine adenocarcinomas of prostatic origin were examined immunohistochemically with antibodies generated against three prostate-specific antigens by using a peroxidase-antiperoxidase technique. Primary antibodies included two generated with human prostatic antigens (PSA, PSAP) and one generated with a canine prostatic antigen (CPSP). Eight of 31 adenocarcinomas were positive with CPSP, two were positive with PSA, and three were PSAP positive. Normal and hyperplastic canine prostatic epithelium was strongly positive with all three markers. These results contrast with those in human studies in which PSA and PSAP stain normal and neoplastic epithelium with comparable intensity in all but the most anaplastic tumors.