Can urethral pressure profilometry predict the response to colposuspension in bitches?

Acquired urinary incontinence in the bitch: update and perspectives from human medicine. Part 3: The urethral component and surgical treatment

Urethral sphincter mechanism incompetence (USMI) is the most common cause of urinary incontinence in dogs. Surgery may be recommended if the animal does not respond to medical treatment or becomes refractory. In this third part of a three-part review, surgical options for the treatment of USMI are described. Colposuspension is the most frequently described procedure and offers a fair prognosis, with about 50% of the dogs being continent after surgery and most of the reminder being improved or more responsive to medical treatment. Urethropexy offers a similar success rate, but with a higher rate of complications. Endoscopic injection of collagen is an attractive technique due to its minimally invasive nature and low risk of adverse effects. Initial results may however deteriorate with time. Other procedures have been reported, but involve a low number of cases and have resulted in variable success rates. In women, stress urinary incontinence is mainly treated by minimally invasive procedures involving vaginal placement of sub-urethral slings.

Evaluation of colposuspension for treatment of incontinence in spayed female dogs

OBJECTIVE

To determine the long-term effects of colposuspension in spayed female dogs with urinary incontinence and identify preoperative anatomic or urodynamic measurements associated with a successful outcome.

DESIGN

Prospective study.

ANIMALS

23 client-owned spayed female dogs with urinary incontinence.

PROCEDURE

Prior to surgery, a history was obtained, and a physical examination, CBC, serum biochemical analyses, urinalysis, bacterial culture of a urine sample, vaginourethrocystography, urethral pressure profilometry, and leak point pressure test were performed. Colposuspension was performed, and preoperative tests were repeated 2 months after surgery. Clients were interviewed 2 weeks, 1 month, and 1 year after surgery.

RESULTS

22 dogs were followed up for 1 year. Twelve had complete urinary control 2 months after surgery, and 3 had complete urinary control 1 year after surgery. Dogs with normal urinary control at 2 months had an increased leak point pressure (LPP), compared with preoperative measurements, and their LPP was the same as normal dogs. Eight dogs had complete urinary control, and 9 were considered greatly improved 1 year after surgery when medical treatment was added to the effect of colposuspension. Client satisfaction was high, with 19 of 22 (86%) owners being pleased with their decision to have surgery performed. The only predictors of complete urinary control 2 months after surgery were a more caudal position of the external urethral opening in relation to the pubis on preoperative radiographs and a longer overall urethral length.

CONCLUSIONS AND CLINICAL RELEVANCE

Colposuspension alone will result in complete urinary control in few dogs with urinary incontinence but may improve urinary control sufficiently that owners will be pleased. Preoperative vaginourethrocystography may be helpful in predicting response to surgery, and the LPP test correlates with improved urinary control.

Immediate urodynamic and anatomic response to colposuspension in female Beagles

OBJECTIVE

To characterize urodynamic function and anatomy before and after colposuspension in anesthetized female Beagles.

ANIMALS

12 adult female Beagles. PROCEDURE; During general anesthesia (thiopental sodium induction and halothane maintenance), urethral pressure profiles, leak point pressure measurements with a 50-ml bladder volume, positive contrast cystograms, and retrograde vaginourethrocystograms were performed. A caudal midline laparotomy was used to perform colposuspension. Urodynamic and radiographic studies were repeated after surgery.

RESULTS

Leak point pressures were increased (120 to 168.9 cm H2O), and maximum urethral closure pressures decreased (43.7 to 19.3 cm H2O ) after colposuspension. The urethra and bladder were moved cranially; the external urethral orifice was positioned closer to the pelvic cavity, and the neck of the bladder was positioned more cranially into the abdomen. Length of the urethra, as measured by use of vaginourethrocystograms, was increased by 3%. As measured by use of urethral pressure profiles, total profile length was increased by 19.9%, and functional profile length was increased by 19.2%.

CONCLUSIONS AND CLINICAL RELEVANCE

Increased leak-point pressure correlated with the expected clinical improvement attributable to colposuspension. Increased exposure of the urethra to abdominal and pelvic cavity pressures may be the mechanism by which incontinent dogs become continent after colposuspension. Results of the leak-point pressure test may correlate with clinical behavior before and after colposuspension for treatment of incontinence.

Developments in the understanding of the pathophysiology of urethral sphincter mechanism in competence in the bitch

Developments in understanding the pathophysiology of urinary incontinence caused by urethral sphincter mechanism incompetence (SMI) are reviewed. SMI is a multifactorial condition; affected bitches have shorter urethras, reduced urethral tone and more caudally positioned bladder necks than continent bitches. Other factors thought to be important in the aetiology of SMI include neutering, breed, body size, docking and obesity. Most of the recent developments in the understanding of SMI have resulted from radiographic and urodynamic investigations of normal and affected bitches. The urodynamic technique of urethral pressure profilometry is discussed and its contribution as an investigative tool reviewed.

Cystourethropexy to correct refractory urinary incontinence due to urethral sphincter mechanism incompetence. Preliminary results in ten bitches

Cystourethropexy was performed in 10 bitches with refractory urinary incontinence due to urethral sphincter mechanism incompetence. All animals had an abnormally shaped vesicourethral junction. The bladder neck was located in the pelvic canal in nine dogs (pelvic bladder). Surgery alone restored urinary continence in two cases and markedly improved incontinence in two cases. Surgery combined with medical therapy (phenylpropanolamine, 1.5 mg/kg orally once or twice a day, using a sustained-action preparation) restored urinary continence in four cases and markedly improved continence in one case. Surgery, with medical therapy, was completely ineffective in one case. No major complications were encountered in any dogs. In four cases, histopathologic evaluation of the dorsal bladder wall and neck revealed the presence of a single, perinuclear, clear vacuole in the cytoplasm of smooth muscle fibers. Electron microscopic examination showed that the vacuoles represented a dilatation of normal membrane organelles. Such abnormalities have the potential to alter the smooth muscle motility. This study indicates that cystourethropexy alone restored urinary continence only temporarily in the majority of the patients. The significance and frequency of the histopathologic findings requires further investigation.