The Immediate Effect of Colposuspension on Resting and Stressed Urethral Pressure Profiles in Anaesthetized Incontinent Bitches

The aim of this study was to document what changes in the resting and stressed urethral pressure profile occur in the incontinent bitch with urethral sphincter mechanism incompetence (SMI) immediately after colposuspension. Resting and stressed subtracted simultaneous urethral pressure profilometry was performed immediately pre- and postcolposuspension in 26 bitches diagnosed with SMI. All of the urethral pressure profiles were measured in anaesthetized bitches using a standard technique and two orientations of the catheter transducers (dorsal and left). Readable pre- and postoperative urethral pressure profiles were obtained in 20 of the 26 bitches. Subjective and objective evaluation of the profiles showed significant differences in the profiles pre- and postcolposuspension. Immediately postoperatively there were significant ( P < .05) increases in functional profile length, maximum urethral closure pressure (MUCP), and distance between the bladder neck and the first negative respiratory peak and stressed spike. There was a significant ( P < .001) decrease in the percentage of negative spikes extending below the resting intravesical pressure on the subtracted profile. The pressure transmission profiles were significantly ( P < .001) altered by surgery. The findings presented support the hypothesis that colposuspension may restore continence by increasing pressure transmission to the proximal urethra and bladder neck. The results also suggest that immediately after surgery functional urethral length and urethral resistance are increased.     

'Simultaneous' urethral pressure profilometry in the bitch: methodology and reproducibility of the technique

The technique of 'simultaneous' urethral pressure profilometry in the bitch is described. Four consecutive recordings were made from each of 100 bitches. From each recording, the maximum urethral closure pressure and functional profile length were measured and assessed for reproducibility. Analyses of variance revealed no significant differences (P greater than 0.2) between the measurements of functional profile length (means: 3.84, 3.84, 3.83, 3.80 cm; standard error of the differences: 0.037) but there were significant variations (P less than 0.001) in maximum urethral closure pressure (means of square roots: 2.26, 2.18, 2.12, 2.08 cm water; standard error of the differences: 0.042). Overall, there was a significant dependence of maximum urethral closure pressure on the measurement order (P less than 0.001). Thus, while functional profile length is a highly reproducible parameter, maximum urethral closure pressure is subject to significant variation.     

Simultaneous urethral pressure profilometry using microtip transducer catheters in the bitch: A comparison of catheter material

Simultaneous urethral pressure profilometry using an 8FG polyurethane microtip transducer catheter in the bitch is subject to considerable variation, Marked differences occur in the parameters normally measured due to the orientation of the transducers and patient position. It has been suggested that a softer catheter may result in less variation. In this study, a comparison was made between 8FG polyurethane and silicone rubber microtip transducer catheters in 35 bitches. There were significant variations in both maximum urethral closure pressure and functional profile length due to catheter type (P < 0–001). Resting intravesical pressure varied with the recording transducer (P < 0–001) and there was a significant interaction between catheter type and recording transducer (P < 0–001). Radiographic measurements on 15 bitches suggested that variations in recorded intravesical pressure were probably related to the location of the transducers of the two catheters within the bladder. It is concluded that the use of a softer catheter material alone is insufficient to eliminate variations resulting from the orientation of the recording sensors within the urethra.     

Comparison of two catheter withdrawal speeds during simultaneous urethral pressure profilometry in anesthetized bitches.

Maximal urethral closure pressure, functional profile length, and number of respiratory peaks on the resting urethral pressure profile, expressed as a percentage of those occurring on the bladder pressure recording, were compared at catheter withdrawal speeds of 1 and 3 mm/s in 30 anesthetized bitches. Significant (P less than 0.001) differences were found in maximal urethral closure pressure and percentage of transmission of respiratory peaks between the 2 speeds. Significant difference was not detected in functional profile length.     

Urethral pressure profilometry in mares

A technique was developed for recording urethral pressure profiles (UPP) in mares. Profiles were obtained from 12 clinically normal mares and from 3 mares with urinary incontinence. Variables measured on the profile included intravesicular pressure and maximal urethral closure pressure. The mean maximal urethral closure pressure of the incontinent mares was significantly less (P less than or equal to 0.001) than that of the normal mares. The technique is simple and reliable for objectively evaluating urethral pressures in mares.     

Clinical evaluation of a single daily dose of phenylpropanolamine in the treatment of urethral sphincter mechanism incompetence in the bitch

The objective of this retrospective study was to determine the efficacy of a single daily oral dose of phenylpropanolamine (PPA) in the treatment of urethral sphincter mechanism incompetence (USMI) in bitches. Nine bitches diagnosed with USMI were treated with a single daily dose [1.5 mg/kg body weight (BW)] of PPA for at least 1 month. Urethral pressure profiles (UPP) were performed in 7 dogs before treatment and repeated in 4 of them after treatment. Treatment with PPA resulted in long-term continence in 8/9 bitches. One dog did not respond to PPA and was treated surgically later. Recheck UPPs showed a significant increase in maximal urethral closure pressure in the 4 bitches after treatment with PPA compared to before treatment. In conclusion, long-term continence can be achieved in bitches affected with USMI after administration of a single daily dose of PPA (1.5 mg/kg BW).     

Pharmacological relaxation of the urethra in male cats: a study of the effects of phenoxybenzamine, diazepam, nifedipine and xylazine.

Urethral pressure profiles (UPPs) were recorded in ten adult healthy male cats before and after administration of either phenoxybenzamine, diazepam, nifedipine or xylazine. A significant decrease (p less than 0.05) in urethral pressure at the level of the prostate was observed following treatment with all drugs. Xylazine produced a significant decrease in urethral pressure 4 to 7 cm from the tip of the penis in healthy male cats. None of the drugs used decreased urethral pressure in the zones of pure striated muscle or pure smooth muscle in these cats, making current recommendations for pharmacological management of urethral spasm suspect. Further studies are necessary to evaluate clinical cases of urethral spasm and to study the effects of these drugs on the urethral pressure of cats suffering from this spasm.     

Electromyographic evaluation of the external urethral sphincter during cystometry in male cats

Electromyographic (EMG) evaluation of the external urethral sphincter (EUS) was conducted during cystometry in 11 adult male cats sedated with xylazine and ketamine. A percutaneously placed antepubic catheter was used for bladder infusion and recording intravesicular pressures during cystometrography (CMG). A fine-wire electrode was placed percutaneously into or near the EUS for recording EMG during CMG. The bladder was infused with sterile 0.9% NaCl solution at a rate of 2 to 3 ml/min until a detrusor reflex was initiated. Intravesicular pressures at the onset of infusion, immediately prior to micturition, at the onset of urine flow, and at the maximal voiding pressure were recorded. The time from infusion to micturition, from opening pressure to return to baseline, and from the beginning to the end of the CMG were also recorded. The total volume of 0.9% NaCl solution infused and the residual bladder volume after micturition were also measured. Recordings were replicated once during each trial in all cats, and trials were replicated once approximately 1 week later in 4 cats. Micturition patterns were characterized by slight to moderate EUS EMG activity during vesicular filling, with reduction in activity during emptying. Maximal EMG activity was recorded at the completion of the reflex and was associated with pulsatile expulsion of small amounts of urine. The simultaneous recording of CMG and EUS EMG with fine-wire electrodes was simple and reliable for assessing the neuromuscular integrity and synchrony of detrusor and EUS muscles. There were no significant differences in variables between recordings within trial 1, but there were differences (P less than or equal to 0.05) between trials for pressure at the onset of urine flow and maximal voiding pressure.     

Effect of atropine on cystometry and urethral pressure profilometry in the dog

Effects of atropine on cystometry and urethral pressure profilometry were examined in 12 healthy young adult dogs by comparing recordings obtained after xylazine alone with those obtained after administration of xylazine and atropine. Significant differences (P greater than 0.05) were not found, indicating that atropine, when administered SC with xylazine, did not markedly affect cystometrographic results and urethral pressure profiles.     

'Simultaneous' urethral pressure profilometry: Comparisons between continent and incontinent bitches

‘Simultaneous’ urethral pressure profilometry using microtip pressure transducer catheters was evaluated as an aid to the diagnosis of urethral sphincter mechanism incompetence by means of comparisons between 50 continent and 50 incontinent anaesthetised bitches. Highly significant differences were detected and the technique was found to have considerable potential as a diagnostic aid.     

Use of fine-wire electrodes for electromyographic evaluation of the external urethral sphincter during urethral pressure profilometry in male cats

Evaluation of urethral pressure profilometry (UPP) with simultaneous fine-wire electromyography of the external urethral sphincter (EUS) was conducted in 11 healthy adult male cats sedated with xylazine and ketamine. A 3.5-F urethral catheter with a closed end and two 1-mm side-ports was infused with sterile 0.9% NaCl solution at a rate of 2 to 3 ml/min. A fine-wire electromyographic (EMG) electrode was placed percutaneously into or near the external urethral sphincter prior to the onset of the UPP. The maximal urethral pressure achieved and functional profile length were recorded from UPP. Setting both catheter withdrawal rate and paper speed at 5 mm/s enabled the measurement of actual urethral length directly from UPP. Sphincter EMG activity was rated as slight (+), moderate (+ +), or intense (+ + +). All recordings were replicated once during each trial for 8 cats and trials were replicated 5 to 7 days later in 4 cats. Before catheterization, EMG activity of the external urethral sphincter was rated slight (+), whereas intense (+ + +) activity accompanied insertion. The activity evoked by movement of the catheter subsided, but intense EMG activity of the external urethral sphincter was recorded from onset to completion of catheter withdrawal in all cats in both trials. The mean maximal urethral pressure was 93.1 +/- 13.29 cm H2O. The mean function urethral length was 8.1 +/- 0.93 cm. Maximal urethral pressure or function profile length did not differ significantly between recordings within trials or between trials. Simultaneous recording of EMG activity and UPP of the external urethral sphincter was shown to be a simple, noninvasive technique for assessing neuromuscular and anatomic urethral function.     

Electromyographic and urethral pressure evaluations: assessment of urethral function in female and ovariohysterectomized female cats

Urethral pressure and electromyographic evaluations were performed in 10 healthy, intact female cats and in 10 healthy, ovariohysterectomized (OVH) female cats. Mean maximum urethral closure pressure was 71.4 +/- 25 cm of water for intact cats and 77.5 +/- 31.3 cm of water for OVH cats. Mean maximum pressure of the proximal 60% of the urethral pressure profile length was 39.2 +/- 7.4 cm of water for intact cats and 32.1 +/- 11.6 cm of water for OVH cats. Mean maximum pressure of the distal 40% of the urethral pressure profile length was 76.2 +/- 27.4 cm of water in intact cats and 80.5 +/- 32.9 cm of water in OVH cats. Significant differences between intact and OVH cats were not found in mean maximum urethral closure pressure, proximal urethral sphincter pressure, or distal urethral sphincter pressure.     

Validation and comparison of the use of diuresis cystometry and retrograde filling cystometry at various infusion rates in female Beagle dogs

OBJECTIVES: To compare retrograde filling cystometry at infusion rates of 5, 10, and 20 mL/min with diuresis cystometry for determination of an appropriate infusion rate and to confirm the reproducibility of measurements obtained by urethral pressure profilometry (UPP) and cystometry in female Beagles. ANIMALS: Adult female Beagles. PROCEDURE: Successive UPP and cystometry were performed by use of a water perfusion catheter on dogs anesthetized with propofol. Dogs randomly underwent each of the following at 1-week intervals: retrograde filling cystometry at 5, 10, and 20 mL/min, and diuresis cystometry. The maximum urethral pressure and closure pressure, functional and anatomic profile lengths, threshold pressure, threshold volume, and compliance were measured. RESULTS: For each UPP variable, significant differences were found among dogs, but no significant differences were found in intra- or interstudy measurements for individual dogs. For retrograde filling cystometry, threshold pressure was not significantly different between a 5 and 10 mL/min infusion rate. Threshold pressure was significantly higher during retrograde filling cystometry at 20 mL/min, compared with 5 and 10 mL/min, and was associated with bladder wall damages. Threshold pressure was significantly lower during diuresis cystometry, compared with retrograde filling cystometries. Threshold volume and compliance were not significantly different among retrograde filling cystometries but were significantly higher during diuresis cystometry. CONCLUSIONS AND CLINICAL RELEVANCE: Retrograde filling cystometry at 20 mL/min leads to unacceptable sudden increase in threshold bladder pressure. Retrograde filling cystometry at 10 mL/min can be recommended in a clinical setting, shortening the anesthesia time. However, diuresis cystometry approximates physiologic bladder filling most accurately.     

Experimental study of urodynamic changes after ovariectomy in 10 dogs

The urodynamic changes in 10 bitches up to 18 months after they had undergone ovariectomy were investigated. There were significant decreases in the maximum urethral closure pressure, the functional urethral length and the total integrated pressure profile 18 months after spaying, resulting in a caudal shift of the urethral profile, and a deterioration of urethral closure function. Each urethral pressure profile was divided into three equal sections; the mean cranial and middle integrated pressure decreased significantly and consistently over the 18-month observation period whereas the caudal integrated pressure increased.     

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.     

Urethral pressure profile and hemodynamic effects of phenoxybenzamine and prazosin in non-sedated male beagle dogs

Prazosin is a readily available alpha-adrenergic antagonist that may be useful in the management of functional urethral obstruction in companion animals. This study used urethral pressure profilometry to evaluate the urethral effects of prazosin and phenoxybenzamine in healthy, non-sedated, male Beagle dogs. Heart rate, indirect systolic, diastolic and mean arterial blood pressures were measured, and saline perfusion urethral pressure profilometry was performed at 0, 10, 20, and 40 min following intravenous administration of prazosin (0.025 mg/kg), phenoxybenzamine (0.2 mg/kg), or placebo. Maximal urethral pressure, maximal urethral closure pressure, post peak nadir, and all blood pressure parameters decreased significantly at nearly all treatment intervals following administration of prazosin compared with placebo. Less consistently significant reductions were observed following phenoxybenzamine administration. Maximal decreases in urethral pressure parameters were observed 20 min following the injection of prazosin; maximal blood pressure decreases were evident by 10 min post- injection. In this non-sedated dog model, urethral pressure profilometry was a sensitive method of detecting urethral effects of alpha antagonists. Repeatable reductions in urethral pressure measurements were observed, with prazosin effecting more consistently significant changes than phenoxybenzamine. Significant decreases in systolic, diastolic, and mean arterial blood pressures were seen with prazosin, but not phenoxybenzamine or placebo. Further study of selective alpha-1 antagonists in dogs is needed to determine appropriate oral dosing protocols that will produce maximal urethral effects with minimal hemodynamic effects, and to demonstrate clinical efficacy in dogs with functional urethral obstruction.     

Evaluation of the urodynamic and hemodynamic effects of orally administered phenylpropanolamine and ephedrine in female dogs

OBJECTIVE: To compare the urodynamic and hemodynamic effects of different dosages of phenylpropanolamine and ephedrine and determine effective dosages in increasing urethral resistance in female dogs. ANIMALS: 20 sexually intact female Beagles. PROCEDURE: Dogs were allocated into 4 groups and received phenylpropanolamine once, twice, or 3 times daily, or ephedrine twice daily, for 14 days. On days 0, 7, and 14, urethral pressure profiles were performed while dogs were anesthetized with propofol. Variables recorded included maximum urethral pressure, maximum urethral closure pressure, integrated pressure, functional profile length, anatomic profile length, plateau distance, distance before maximum urethral pressure, and maximum meatus pressure. Arterial and central venous pressures were measured before anesthetic induction and 10 and 35 minutes after induction. RESULTS: Administration of phenylpropanolamine once daily or ephedrine twice daily significantly increased maximum urethral pressure and maximum urethral closure pressure. Values for integrated pressure were significantly increased after 14 days of once-daily administration of phenylpropanolamine. Variables did not change significantly from day 7 to day 14. Diastolic and mean arterial blood pressures increased significantly during the treatment periods, and arterial pressure decreased during propofol infusion. CONCLUSIONS AND CLINICAL RELEVANCE: Oral administration of phenylpropanolamine once daily or ephedrine twice daily increased urethral resistance in clinically normal dogs and may be recommended for management of urethral sphincter mechanism incompetence. Treatment efficacy may be assessed after 1 week. Dogs with concurrent cardiovascular disease should be monitored for blood pressure while receiving alpha-adrenergic agents because of the effects on diastolic and mean arterial pressure.     

Effects of xylazine on the urethral pressure profile of healthy dogs

Thirteen healthy male dogs and 11 healthy female dogs were subjected to urodynamic assessment, using a simultaneous urethral pressure profile and urethral sphincter electromyogram (EMG). The study was done on the dogs in the nonsedated state and after xylazine sedation. Results showed a significant decrease in maximal urethral closure pressures in dogs of both sexes after they were given xylazine (from 79.79 cm of H2O to 23.00 cm of H2O in female dogs, and from 99.77 cm of H2O to 41.77 cm of H2O in male dogs). There was a significant reduction in EMG activities in dogs of both sexes after they were given xylazine. There was also little variability in measurements made on the same dog on consecutive days. Simultaneous intravesicular pressure and urethral pressure monitoring indicated that the effect of bladder distention on the urethral pressure profile was minimal and that there were no spontaneous detrusor contractions. This study indicates that xylazine produced a significant artifact in the simultaneous urethral pressure profile/EMG.     

Urodynamic and morphologic changes in the lower portion of the urogenital tract after administration of estriol alone and in combination with phenylpropanolamine in sexually intact and spayed female dogs

OBJECTIVE: To compare the urodynamic and morphologic effects of the administration of estriol alone and in combination with phenylpropanolamine on the lower portion of the urogenital tract in female dogs. ANIMALS: 3 sexually intact and 3 spayed female Beagles without urinary incontinence. PROCEDURE: Dogs received estriol (2 mg, PO) once daily for 7 days followed by estriol (2 mg, PO) and phenylpropanolamine (1.5 mg/kg, PO) once daily for 7 days. Urethral pressure profilometry, diuresis cystometry, and vaginourethrography were performed before treatment (day 0) and at days 7 and 14. The maximum urethral pressure (MUP) and closure pressure (MUCP), urethral functional and anatomic profile lengths, integrated pressure (IP), plateau, distance before MUP, maximum meatus pressure, threshold pressure, threshold volume, compliance, urethral length, and vaginal length and width were measured. RESULTS: Before treatment, no urodynamic differences were observed between the 2 groups; however, vaginal length and width were significantly shorter in spayed dogs. Compared with day 0 values, estriol treatment significantly increased MUP, MUCP, and IP values at day 7, but at day 14, this effect decreased despite phenylpropanolamine administration. No morphologic changes from baseline were detected after either treatment in any dog. CONCLUSIONS AND CLINICAL RELEVANCE: Data suggest that estriol mainly acts on the urethral sphincter mechanism by increasing urethral resistance in sexually intact and spayed female dogs without urinary incontinence. Administration of estriol and phenylpropanolamine did not increase the urethral resistance more than estriol alone. The urodynamic effects of estriol in female dogs with urinary incontinence remain to be elucidated.     

Urodynamic Evaluation of Lower Urinary Tract Function in Cats After Perineal Urethrostomy with Minimal and Extensive Dissection

Perineal urethrostomy was performed in five male cats with minimal, sharp intrapelvic transection of the ischiocavernous and ischiourethralis muscles and ventral penile ligaments, and in five male cats with extensive blunt intrapelvic dissection and sharp muscle transection. Urethral pressure profiles and cystometrograms with simultaneous fine wire electrode sphincter electromyography were performed in sedated cats before surgery and on days 14 and 28. Premicturition pressure, urethral opening pressure, maximum detrusor pressure, total volume infused, and residual volume were measured during cystometry, and maximal urethral closure pressure was measured during profilometry. A grading of (+), (++), or ( ) was used to represent the intensity of electromyographic activity. There was no difference between minimal and extensive dissection for any cystometrogram or profile variable at days 14 or 28. Urethral opening pressure and maximal detrusor pressure during cystometrography were higher in preoperative studies than after minimal or extensive dissection. Sphincter electromyography after surgery was not significantly different from preoperative results in either surgical group. The results of this study indicate that neither sharp nor blunt intrapelvic dissection significantly alters the postoperative urodynamic status in male cats.