Prostatic Masses in Geldings: Two Cases

Prostatic masses were detected in two geldings that were presented to our referral hospital for evaluation of dysuria. The masses were detected during transrectal palpation and ultrasonography of the prostate gland and were further evaluated using urethral endoscopy. A 10-year-old gelding underwent intraurethral debulking of the prostatic mass. Histopathological diagnosis was prostatic cystadenoma. The mass regrew within 9 months, and the horse was euthanized due to deteriorating clinical control of urinary continence. In another case, a 12-year-old gelding was scheduled for transurethral debulking; however, the owners decided against treatment and the horse was euthanized due to progression of clinical disease. Postmortem examination revealed the prostate to be nearly completely obliterated by the mass. Histopathological diagnosis was adenocarcinoma incorporated into a spindle cell population of unknown histogenesis. To our knowledge, these represent the first reported cases of equine prostatic cystadenoma and adenocarcinoma. In both horses, referring complaint was dysuria, and identification of the prostatic mass was made on palpation and ultrasonographic examination per rectum. Treatment options for prostatic masses in horses are limited because of the difficulty of obtaining prostatic tissue via biopsy, the surgical inaccessibility of the gland, and the apparent low incidence of occurrence. We have subsequently identified prostatic masses in two additional geldings, both also presenting for dysuria. However, the exact nature of these two apparent prostatic masses has not been definitively diagnosed with histopathological examinations to date. The prostate should be evaluated in male horses presenting for dysuria.