Prostatic Neoplasia: Does Total Prostatectomy Help?

While prostatic neoplasia is relatively rare in dogs, it is typically associated with a poor prognosis due to the high risk of local invasion or metastasis. Also, current therapeutic options are generally associated with poor response and a high risk of complications.

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Researchers recently performed a multi-institutional retrospective study to describe treatment outcome after total prostatectomy in canine patients.

Study Design

Data were retrieved from the medical records of dogs undergoing total prostatectomy for prostatic neoplasia from October 2004 through August 2016. Postoperative complications were classified as minor (self-limiting or medically managed) or major (life-threatening or surgically managed). Initial diagnosis, metastasis, and tumor recurrence were all cytologically or histologically confirmed.

Results

The study included records from 25 neutered male dogs representing 20 breeds. Median age and weight were 9.3 years and 25.0 kg, respectively. The most common presenting clinical signs were dysuria (48%), dyschezia (32%), hematuria (24%), and pollakiuria (24%). An enlarged prostate was palpable on rectal examination in 16 dogs, and 2 dogs had palpable abdominal masses. Hematuria was present in 87% of urine samples, and 3 of 6 urine cultures had bacterial growth.

Preoperative imaging revealed prostatomegaly in 24 of 25 dogs. Preoperative cytology, which was performed in 20 dogs, classified tumors as carcinoma (85%), epithelial dysplasia (10%), or squamous metaplasia (5%). Preoperative histopathology of tumors from 3 dogs classified tumors as transitional cell carcinoma (66%) or prostatic adenocarcinoma (34%).

Total prostatectomy was performed for all dogs via caudal ventral midline celiotomy. Urethrourethral or cystourethral anastomosis was possible for all but 2 dogs. All dogs received postoperative analgesia, and urinary catheters were maintained in 20 dogs for a median of 4 days after surgery.

Although all dogs survived to discharge, postoperative complications included urinary tract infection (24%), incisional dehiscence (8%), surgical site infection (8%), uroabdomen due to a lacerated bladder (4%), and prepubic herniation (4%). Temporary (60%) or permanent (32%) urinary incontinence was common after surgery.

Postoperative histology characterized prostatic tumors as:

• Transitional cell carcinoma (60%)
• Adenocarcinoma (32%)
• Undifferentiated carcinoma (4%)
• Papillary cystadenocarcinoma (4%)

Complete tumor excision was possible in 40% of cases. Extracapsular extension was noted in 55% of tumors, while lymphatic and/or vascular invasion had occurred in 65% of cases.

Curative-intent chemotherapy was performed for 15 dogs, but was discontinued in 5 cases due to adverse effects or development of metastasis. Eighty-four percent of all patients eventually experienced local tumor recurrence and/or metastasis. Median disease-free interval between surgery and recurrence of neoplasia, which was measured for 14 dogs, was 81.5 days.

Median survival time (MST) for all dogs was 231 days (range, 24-1255 days). Extracapsular extension was significantly associated with shorter MST. Adjunctive treatments, including chemotherapy, did not significantly improve MST. Twenty-two dogs died during the study, 19 of which were from tumor-related causes.

Take-home Message

Complications occurred less frequently and survival was longer than in previous reports of dogs undergoing total prostatectomy. Urinary incontinence remained the most frequent postoperative side effect.

Dr. Stilwell received her DVM from Auburn University, followed by a MS in fisheries and aquatic sciences and a PhD in veterinary medical sciences from the University of Florida. She provides freelance medical writing and aquatic veterinary consulting services through her business, Seastar Communications and Consulting.