When medical therapy fails to treat urethral sphincter mechanism incompetence (USMI) or if unwanted effects occur, surgical intervention may be necessary. The safety and efficacy of a surgically implanted adjustable urethral sphincter (AUS) was reviewed in 24 female and 3 male dogs with acquired or congenital urinary incontinence: 18 had USMI, 6 were incontinent following ectopic ureter repair, and 3 had pelvic bladder. Following midline celiotomy, a 2-cm section of proximal urethra was isolated and a silicone urethral compression cuff placed around it and secured. The AUS actuating tube was then passed via stab incision through the abdominal wall and attached to a subcutaneous vascular access port located cranial to the flank fold. Urethral patency was tested with sterile saline before lavage and closure. AUS inflation was repeated q1wk until incontinence resolved. At owner survey 6–19 months postoperatively, continence scores improved and owners described themselves as very satisfied (22/27), satisfied (2/27), or unsatisfied (3/27). Complications included mild transient postoperative stranguria. Twelve dogs were continent after AUS implantation without requiring AUS cuff inflation. AUS removal was recommended in 2 dogs that developed functional urethral obstruction, possibly from scar tissue at AUS site and preexisting detrusor dysfunction. AUS implantation may be an effective treatment, but urethral obstruction may occur.

Commentary
Surgical implantation of AUSs has been the next solution attempted for USMI-related incontinence in dogs. Inclusion of both sexes provided a realistic clinical picture with encouraging results. Most dogs, one-third of which showed significant anatomic urinary tract problems, showed significantly improved continence. Some dogs did not need the AUS inflated (the shape itself provided focal compression); however, this close apposition may be a device defect as urethral obstruction was a noted complication. A chronic, foreign body-like fibrous reaction or chronic focal pressure may result in functional obstruction the bladder cannot overcome, requiring device removal. This was only noted in 2 dogs, providing promising results for owners willing to commit to surgery and maintenance.—Kristy Broaddus, DVM, MS, DACVS

Source
Outcome after placement of an artificial urethral sphincter in 27 dogs. Reeves L, Adin C, McLoughlin M, et al. VET SURG 42:12-18, 2013.