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.     

Preservation of striated-muscle urethral sphincter function with use of a surgical technique for perineal urethrostomy in cats

It has been reported that perineal urethrostomy resulted in impairment of striated-muscle urethral sphincter function in male cats, as measured by urethral pressure profilometry and electromyography (EMG). Our study was undertaken to describe and evaluate a surgical technique for perineal urethrostomy that reduces trauma to the urethral branches of the pudendal nerve. Perineal urethrostomy was performed on 10 healthy neutered cats after demonstrating that they had normal urethral sphincter function by urethral pressure profilometry (maximal urethral closure pressure [MUCP] = 151 +/- 52 cm of water) and EMG activity at the level of the striated-muscle sphincter before surgery. All cats had normal urethral sphincter function 1 week (MUCP = 194 +/- 19 cm of water, EMG activity present) and 3 weeks (MUCP greater than 200 cm of water, EMG activity present) after surgery. These results indicated that preservation of the urethral branches of the pudendal nerve during urethrostomy preserved striated-muscle urethral sphincter 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.     

Stress leak point pressures and urethral pressure profile tests in clinically normal female dogs.

OBJECTIVE: To develop a stress leak point pressure (LPP) test for dogs, determine LPP for continent female dogs, and determine urethral pressure profile (UPP) values for nonanesthetized, continent female dogs. ANIMALS: 22 continent female dogs weighing from 21 to 29 kg. PROCEDURE: A standard UPP test and a modification of the LPP test used in women were performed on all dogs. On 3 occasions, dogs underwent UPP testing while awake. They then were anesthetized with propofol, and LPP was measured at bladder volumes of 75, 100, and 150 ml. For LPP tests, abdominal pressure was applied by inflating a human blood pressure cuff placed around the dog's abdomen. LPP were recorded through a urethral catheter (bladder LPP) and a rectal balloon catheter (abdominal LPP). RESULTS: Mean +/- SD and median maximal urethral closure pressure was 110.1+/-20.2 and 109.0 cm water, respectively. Mean bladder LPP for the 75, 100, and 150 ml bladder volumes was 172.4 cm water. Significant differences among LPP for the 3 bladder volumes were not detected. CONCLUSIONS: Stress LPP can be recorded in female dogs.     

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.     

Four cases of lowered urethral pressure in canine ectopic ureter

To evaluate the function of the constrictor urethrae of dogs that had urinary incontinence and were diagnosed as having ectopic ureter, the urethral pressure profile (UPP) was measured by means of a microchip catheter transducer. The UPPs (14.5 +/- 3.3 mmHg) of the four dogs suffering from ectopic ureter were much lower (p<0.001) than the UPPs of clinically healthy female dogs (35.3 +/- 5.7 mmHg). In the cases of ectopic ureter, it was shown that the UPP was lowered, and it was suggested that this would lead to the expression of urinary incontinence.     

Management of traumatic urethral rupture in 11 cats using primary alignment with a urethral catheter

OBJECTIVE: To assess the management of traumatic urethral ruptures using a systematic attempt at urethral catheterisation. METHODS: Eleven cats that had been diagnosed with a traumatic urethral rupture over a five-year period were included in this study. Rupture was assessed by positive-contrast retrograde urethrography. An attempt was made to manage these ruptures by placing an indwelling urethral catheter. RESULTS: The placement of an indwelling urethral catheter, could be performed in 10 out of 11 cats, which indicated a partial rupture. In one cat, catheterisation was not possible because of complete urethral rupture. A urethral catheter was placed into the urinary bladder via the urethra in five animals. In the other five animals, urethral catheterization required cystotomy using a modified 'inside to outside' technique. Urethral catheter removal occurred between five and 14 days after placement. Urethral healing was accomplished in all cases of catheterisation with a good outcome in eight of the 10 cats. Two cats showed clinical signs related to stricture formation during the follow-up period (seven to 72 months). Retrograde urethrography provided a definitive diagnosis of partial rupture in only six of the 10 cases of partial rupture. CLINICAL SIGNIFICANCE: Results suggested that primary alignment with the placement of a urethral catheter should be attempted for the management of traumatic urethral ruptures in cats. Gentle urethral catheterisation seems to be an effective procedure for diagnosing and dealing with partial urethral rupture in cats. Clinical stricture formation can occur, but the risk does not seem to be high. Further studies are warranted in order to define the ideal duration for maintenance of an indwelling urethral catheter in cases of traumatic partial urethral rupture.     

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 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.     

Results of cystometry and urethral pressure profilometry in dogs sedated with medetomidine or xylazine

OBJECTIVE: To compare effects of medetomidine and xylazine hydrochloride on results of cystometry and micturition reflexes in healthy dogs and results of urethral pressure profilometry (UPP) in sedated and conscious dogs. ANIMALS: 20 dogs. PROCEDURES: Urodynamic testing was performed 6 times in each dog (3 times after administration of xylazine [1 mg/kg of body weight, IV] and 3 times after administration of medetomidine (30 microg/kg, IM). Before each episode of sedation, UPP was performed. Heart and respiratory rates and indirect blood pressures were recorded prior to and 5, 10, 20, and 30 minutes after injection of sedative. Cystometry measurements included threshold volume, threshold pressure, and tonus limb. The UPP measurements included maximal urethral closure pressure (MUCP), functional profile length, and, in male dogs, plateau pressure. RESULTS: Mean MUCP was decreased markedly in xylazine- and medetomidine-sedated dogs. Xylazine and medetomidine also decreased plateau pressure in male dogs. The MUCP measurements were consistent among days for conscious and xylazine-sedated dogs but were inconsistent for medetomidine-sedated female dogs. The proportion of valid cystometry measurements was greater for xylazine (39 of 60) than for medetomidine (27 of 60). Cystometry was considered invalid when bladder pressure reached 30 cm H2O without initiation of a micturition reflex. CONCLUSIONS AND CLINICAL RELEVANCE: Medetomidine and xylazine have similar effects on measurement of UPP and cystometry. Medetomidine was less consistent among days for UPP in female dogs and produced fewer valid cystometry tests, compared with xylazine. For urodynamic evaluations, medetomidine administered IM cannot be substituted for xylazine administered IV.     

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).     

Prevalence of bacterial urinary tract infection after perineal urethrostomy in cats.

It has been reported that the prevalence of bacterial urinary tract infection (UTI) increases after perineal urethrostomy in male cats. Perineal urethrostomy, using a surgical technique preserving striated urethral sphincter function, was performed on 2 groups of cats. The first group consisted of healthy castrated cats. The second group of cats had recurrent or persistent urethral obstruction. All cats had normal urethral sphincter function after surgery, as measured by urethral pressure profilometry and electromyography. Long-term periodic urinalysis and bacterial culturing of urine was performed on all cats. Twenty-two percent of the previously obstructed cats had recurrent bacterial UTI, compared with none of the healthy cats. On the basis of these findings, we suggest that perineal urethrostomy per se does not predispose cats to bacterial UTI, but surgical alteration of the urethral meatus combined with an underlying uropathy may increase the prevalence of ascending bacterial UTI after surgery.     

Urodynamic testing in the diagnosis of small animal micturition disorders

Urodynamic testing provides a quantitative assessment of the function of the small animal lower urinary tract. Most commonly these techniques are utilized to assess urethral tone (urethral pressure profile or UPP) and bladder detrusor muscle function (cystometrogram or CMG). A UPP may be indicated in cases of canine and feline micturition disorders. Examples include suspected primary sphincter mechanism incontinence (PSMI), ureteral ectopia, other congenital abnormalities, suspected neurological disorders, and mechanical or functional urethral obstruction. A UPP can be performed effectively utilizing human dedicated equipment. A CMG may be indicated to assess detrusor function in all of the above cases as well as cases of suspected atonic or infiltrated urinary bladder. This procedure can also be performed using the same human equipment. These tests are useful not only in providing an accurate diagnosis, but also in providing a sensitive prognostic indicator for clinical outcome of micturition disorders with and without pharmacological or surgical therapy. A leak pressure point may also be established in dogs with urinary incontinence, and may be even more sensitive than a UPP to predict clinical incontinence in some cases.     

Transobturator vaginal tape inside out for treatment of urethral sphincter mechanism incompetence: preliminary results in 7 female dogs

Objectives: To evaluate the clinical efficacy of the transobturator vaginal tape inside‐out (TVT‐O) in incontinent female dogs affected with urethral sphincter mechanism incompetence (USMI) and to determine its urodynamic and morphologic effects. Study Design: Case series. Animals: Incontinent spayed female dogs (n=7). Methods: TVT‐O tape was inserted in 7 incontinent female dogs diagnosed with USMI. Urethral pressure profilometry (UPP) and vaginourethrograms were performed preoperatively, and 1 and 3 months postoperatively. Clinical efficacy of the technique was evaluated and complications reported. Follow‐up information was evaluated by a telephone questionnaire. Results: All dogs were continent immediately after the procedure. Incontinence recurred 2 months after surgery in 1 dog and was treated by phenylpropanolamine administration. At mean follow‐up time of 11.3 months, 6 of 7 dogs were continent. An iatrogenic urethral tear occurred intraoperatively in 1 dog. No postoperative complications were encountered. The postoperative UPPs showed significantly increased maximal urethral closure pressure and integrated pressure. Postoperative vaginourethrograms were unremarkable. The surgical procedure did not modify the location of the urinary bladder neck in dogs with a “pelvic urinary bladder” preoperatively. Conclusions: TVT‐O was efficient in maintaining short term continence in 6 of 7 dogs affected with USMI.     

'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.     

Clinical response and urethral pressure profile changes after phenylpropanolamine in dogs with primary sphincter incompetence

Based on clinical response, urethral pressure profile changes, and lack of side effects, phenylpropanolamine was effective and safe in treating dogs with primary sphincter incompetence. Primary sphincter incompetence was diagnosed in 11 female and 8 male dogs with urinary incontinence. Urodynamics of the dogs were assessed, using a combined urethral pressure profile and urethral sphincter electromyography. Male and female dogs had significantly (P less than 0.05) lower maximal urethral closure pressures, when compared with clinically normally dogs (36.91 +/- 8.20 cm of H2O vs 79.72 +/- 4.61 cm of H2O for female dogs and 48.63 +/- 8.68 cm of H2O vs 99.77 +/- 11.71 cm of H2O for male dogs). After treatment with phenylpropanolamine, there was a significant increase in maximal urethral closure pressure in both sexes to within normal range (77.73 +/- 8.70 cm of H2O in females and 92.50 +/- 14.60 cm of H2O in males). Electromyographic activity was normal before and after treatment. Urinary incontinence resolved clinically in all but 1 male and 1 female dog; however, the condition in these 2 dogs improved considerably. Minimal side effects were seen clinically. Mean arterial blood pressure was not altered by treatment. Plasma estrogen and testosterone concentrations in 8 female dogs were not different from those in continent female dogs. The incontinence in these dogs was considered a sphincter incompetence rather than estrogen responsive.     

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.     

Effects of thiopentone, propofol, alphaxalone-alphadolone, ketamine and xylazine-ketamine on lower oesophageal sphincter pressure and barrier pressure in cats

The anaesthetic induction agents thiopentone, propofol and alphaxalone-alphadolone were administered to cats intravenously and ketamine and xylazine-ketamine-atropine were administered intramuscularly in order to determine their effects on gastric pressure, lower oesophageal sphincter pressure, and barrier pressure. Manometric measurements were made with a non-perfused catheter tip pressure transducer. All the anaesthetic induction agents decreased the tone of the lower oesophageal sphincter but the reduction was least with ketamine. Lower oesophageal sphincter tone was significantly higher in cats anaesthetised with either xylazine-ketamine-atropine or propofol than in cats anaesthetised with either thiopentone or alphaxalone-alphadolone. Despite a higher gastric pressure in the cats anaesthetised with ketamine rather than with the other drugs except propofol, the barrier pressure was also significantly higher in cats anaesthetised with ketamine than in cats anaesthetised with any of the other drugs except xylazine-ketamine-atropine. The risk of gastrooesophageal reflux seemed to be higher with alphaxalone-alphadolone than with thiopentone if the lower oesophageal sphincter pressure and gastric pressure are used as indicators of likely reflux.     

'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.