Transobturator Vaginal Tape for Treatment of Urinary Incontinence in Spayed Bitches
This study investigated the long-term effectiveness and safety of a variant of the transobturator vaginal tape inside-out technique for acquired urinary incontinence. Twelve spayed female dogs were operated over a 2 yr period. No intraoperative complications were encountered. Transient dysuria was the most common postoperative complication (7 out of 12 dogs). On the 12th day postoperatively, incontinence was completely cured in 11 out of 12 dogs (92%). At the time of the second evaluation (median follow-up time was 21 mo), patients classified as “cured,” “greatly improved,” or “improved” were 25, 50, and 25% of the total, respectively. At the time of either the fourth evaluation or at the time of death (median follow-up time was 52 mo), 50% of the bitches (6 out of 12) had the same results as previously but the other 50% had leakage that reappeared sporadically. A fistula appeared on the path of the tape in two bitches at 28 and 32 mo postsurgically. The technique presented is effective and more cost effective than the standard technique and could constitute an attractive alternative; however, it could be associated with an immediate postoperative dysuria, delayed fistula formation, and a partial recurrence of clinical signs.
Introduction
Sterilization is the most common cause of acquired urinary incontinence in the female dog, with about 10% of bitches becoming incontinent after being spayed (range, 5.1–20.1%).1,2 The success rate of medical treatment is about 82% with estriol (an estrogen) and 86% with phenylpropanolamine (an α-adrenergic agonist).3,4 Surgery may be an attractive alternative if female dogs have an unsatisfactory response to medical treatment or to avoid life-long medical treatment. Despite dissimilarities between incontinence in women and incontinence in female dogs, surgeries used in women to treat stress incontinence are also effective for treating acquired urinary incontinence in spayed female dogs.5,6 It is reasonable to investigate whether recent surgical treatments that are effective in women may also be effective in female dogs.
Since the 1990s, an intravaginal slingplasty called “tension-free vaginal tape” (TVT) has become the most popular surgical procedure for the treatment of female urinary stress incontinence throughout the world in humans.7,8 In that technique, a tape acts as a support and allows the urethra to remain closed during periods of increased intra-abdominal pressure. TVT is as effective as colposuspension. Its success rate is >92% with similar complication rates.9,10 TVT is a minimally invasive and rapid technique, with a mean operating time of only 33 min for TVT versus 108 min for colposuspension.11 TVT is 60% lower in cost.11
A variant, the “transobturator tape” (TOT) procedure, limits the risk of bladder perforation, so that postoperative cystoscopy is no longer absolutely necessary.12 In another variant, the “transobturator vaginal tape inside-out” (TVT-O) technique, the tape is inserted from inside to outside to avoid injury to the urethra, vessels, nerves and bowel due to the blind passage of the needle through the retropubic space.13 The adaptation of the TVT-O procedure is safe and effective in the female dog. Reports indicate that the procedure resulted in continence of six out of seven dogs, with no major complications.14,15
Many devices have been used to perform the TVT, TOT, and TVT-O procedures, with costs approximating US$650, excluding taxes. The purpose of this retrospective study was to investigate the long-term safety and efficacy of a variant of the TVT-O technique using inexpensive equipment for the surgical treatment of acquired urinary incontinence in spayed female dogs.
Materials and Methods
Patients
Medical records of client-owned female dogs with poststerilization-acquired urinary incontinence presented to the authors' institution during a 25 mo period between March 2006 and April 2008 were reviewed. Because of a lack of the instrumentation required to measure urethral pressure profiles, the diagnosis of spay incontinence was made on the basis of a detailed history and consistent clinical signs. No vaginourethrograms, abdominal ultrasounds, or urine cultures were performed. The inclusion criteria included adult females dogs with incontinence acquired after spay, dogs referred by another veterinarian either due to the severity of their incontinence and/or due to the failure of medical treatment (to avoid recruitment bias). The incontinence caused involuntary loss of urine especially at rest (sleeping or relaxing) and possibly during exercise (when walking, playing, barking, coughing, arising, etc.). Incontinence was considered to be severe (i.e., with leakage of urine at least several times/wk), without periods of remission, and with normal micturition and normal urinalysis. The exclusion criteria were male dogs, incontinence appearing either before the age of 6 mo or before sterilization (to rule out congenital urinary incontinence, a condition sometimes associated with multiple abnormalities), pollakiuria, dysuria, or observation of bacteriuria on microscopic examination, urine specific gravity <1.020 (to rule out polyuria), and previous surgical treatment for incontinence (to ensure that part of the success/complications was not attributable to the first intervention).
Information relative to the dog's history was collected during the first examination (i.e., name, breed, date of birth, medical history, weight, date of sterilization, nature of the sterilization (ovariectomy or ovariohysterectomy), time between sterilization and appearance of incontinence, circumstances and frequency of urine leakage, and previous treatments and their results.
Surgical Technique
All procedures were performed by the same surgeon (J-Y.D.). Patients were placed in dorsal recumbency with the legs drawn forward in hyperflexion and abduction to obtain maximum exposure of the perineum. The anus was closed by a purse string suture, and the bladder was emptied. The only special material necessary for this procedure was a 10 cm curved Reverdin needle with an eye large enough to accommodate the synthetic tape (i.e., a needle designed for bovine surgical procedures) and a woven nonabsorbable tapea. The tape was passed through the eye of the needle. An episiotomy was performed to provide easy access to the urethral meatus. A Foley catheter was inserted into the meatus to avoid perioperative micturition and to mark the urethra during the procedure. A 1 cm vertical midline incision was made through the whole thickness of the vaginal wall beginning 1 cm proximal to the urethral meatus (Figure 1). The needle was introduced through the vaginal incision at a 45°angle to the sagittal plane and then directed craniolaterally, dorsally to the dorsal surface of the ischiopubic bone, keeping the tip in contact with that bone (Figure 2). The needle was advanced along the bone until a loss of resistance marked the caudal boundary of the obturator foramen. The needle was advanced along a curved path until the skin was at first deformed then penetrated on the midline (Figure 3). A 2 cm transverse skin incision was made at that level then the needle was completely exteriorized and the tape freed from the needle. The same procedure was performed on the other side with the other end of the tape, using the same needle. Both free ends of the tape should exit the body at approximately the same location (Figure 4). The middle part of the tape was laid flat against the urethra so that contact between the tape and the urethra was maximized (Figure 5). Both emergent free ends of the tape were simultaneously pulled to remove slack (Figure 6). Slight tension was introduced without compressing the urethra by applying too much tension to the tape. Traction was stopped when the tape made contact with the urethra (as soon as the catheter began to move). It is important that the urinary catheter must be able to move without resistance. The free ends of the tape were knotted together, leaving a 1 cm space between the double knot and the abdomen (Figure 7). The double knot was buried in the subcutaneous tissue, and the skin incision was closed. The tape retains its O shape, located in the distal third of the urethra, just proximal to the urethral meatus (Figure 8). The vaginal incision was sutured, the episiotomy closed, and the Foley catheter removed.
Citation: Journal of the American Animal Hospital Association 51, 2; 10.5326/JAAHA-MS-6215
Citation: Journal of the American Animal Hospital Association 51, 2; 10.5326/JAAHA-MS-6215
Citation: Journal of the American Animal Hospital Association 51, 2; 10.5326/JAAHA-MS-6215
Citation: Journal of the American Animal Hospital Association 51, 2; 10.5326/JAAHA-MS-6215
Citation: Journal of the American Animal Hospital Association 51, 2; 10.5326/JAAHA-MS-6215
Citation: Journal of the American Animal Hospital Association 51, 2; 10.5326/JAAHA-MS-6215
Citation: Journal of the American Animal Hospital Association 51, 2; 10.5326/JAAHA-MS-6215
Citation: Journal of the American Animal Hospital Association 51, 2; 10.5326/JAAHA-MS-6215
Follow Up
During the postoperative period, each dog was fitted with an Elizabethan collar and received 5 days of oral meloxicamb. Patients exhibiting pain received additional opioids. After observing adequate voiding function, patients were discharged from the hospital. The patients were examined again on the 12th day postsurgically for suture removal. Clinical assessments were conducted by independent investigators (i.e., clinical instructors who were not included as coauthors). In January 2009, January 2012, and January 2013, all owners received a questionnaire. Effectiveness was evaluated according to either the disappearance or diminution of involuntary loss of urine. Dogs were assigned to one of five categories: “cured” (no episodes of urine leakage), “greatly improved” (episodic urine leakage ≤1×/mo), “improved” (rare but regular urine leakage one or more times/mo),"insufficient” (frequent urine leakage or need for additional medication), and “no improvement or worsening.” For dogs that died during the study period, status at the time of death was noted.
Results
Twelve female dogs with spay incontinence were included (Table 1). Breeds represented included the Labrador retriever (n = 3), Doberman pinscher (n = 3), boxer (n = 2), Great Dane (n = 1), fila Brasileiro (n = 1), wirehaired pointing griffon (n = 1), and giant schnauzer (n = 1). Median weight was 30 kg (mean, 34 kg; range, 25–70 kg). Median age at the time of surgery was 5.5 yr (mean, 5.6 yr; range, 3.2–9.8 yr). Median age at sterilization was 3 yr (mean, 3.2 yr; range, 0.7–9.5 yr). Median time between sterilization and incontinence was 1.7 years (mean, 1 yr; range, 0.1–8 yr). Half of the patients had an ovariectomy, and the other half had an ovariohysterectomy.
Presentation
All dogs had urine leakage at rest when lying down. All except one dog (92%) had leakage both at night and during the day. One patient (8%) had leakage of urine only during the day, especially after muscular effort. One patient dripped urine when arising, one patient when coughing, and two patients (17%) had permanent leakage even when walking. Six owners (50%) spontaneously mentioned puddles or pools of urine. In all cases, incontinence was considered to be severe: permanently (when lying down and when walking) in two dogs, continually at rest for three dogs; several times/day for three dogs, once/day for three dogs, and several times/wk for the remaining dog. In all cases, medical treatment had been tried, including phenylpropanolamine, estriol, or both. In two cases, medical treatment had been successful, in six cases the treatment was partially successful at first but later unsuccessful, and in four cases treatment had no effect.
Surgical Procedure
Median operation time was 45 min (mean, 50 min; range, 35–70 min). The longest surgery lasted 70 min because of difficulty in finding the left obturator foramen. The most time-consuming part of the operation was the episiotomy and its reconstruction. There were no major intraoperative complications and no significant bleeding. In most cases it was easy to find the obturator foramen and to withdraw the tip of the needle exactly at the level of the skin the authors selected. Five cases proved to be more difficult to find the left obturator foramen than the others.
Immediate Postoperative Complications
Immediate postoperative micturition disorder (dysuria or stranguria) was the most common complication, which was observed in seven dogs just after the surgery for a 2–7 day period. Temporary urinary catheterization with a Foley catheter was performed for a 3 day period in four cases. In one Great Dane weighing 70 kg, two tapes were placed side by side because one 6 mm tape was not thought to be wide enough for a large dog. That dog presented with a severe dysuria. Under anesthesia, urethral catheterization with a metal probe was difficult because of compression of the urethra by the tapes. The knots of the tapes were cut and the urethra was decompressed by moving the ribbon with a rigid metal probe. The tapes were left in place. The dysuria disappeared and that dog remained “greatly improved” despite the knots having been cut.
Pain was observed postoperatively for a short period in three dogs but none of them had received epidural analgesia before the surgery. In four dogs, dark vulvar discharge was observed after surgery. It was thought that the blood had accumulated in the vagina during surgery. The knot was palpable under the skin in three dogs, with no negative consequences. Mean time between surgery and discharge was three days (range, 1–7 days).
Outcome and Long-Term Complications
At the time of the first evaluation, at suture removal on the 12th day postoperatively, incontinence was completely cured (no episodes of leakage) in 11 out of 12 patients (92%). Either a cure or an improvement was observed immediately following the discharge of 9 dogs (75%), and some days thereafter in 2 dogs (17%). One patient (8%) did not improve. In that dog, a very nervous boxer, a second surgery was performed 4 mo later and the first tape was found to have broken. The tape was removed and replaced with another one. That dog became continent a few days after the second surgery and remained “greatly improved."
At the time of the second evaluation, in January 2009 (median follow-up time, 21 mo; mean, 21 mo; range, 9–34 mo), three patients (25%) were “cured” (no episodes of urine leakage), six patients (50%) were “greatly improved” (episodic leakage ≤1×/mo) and three patients (25%) were “improved” (rare but regular loss of urine ≥1×/mo). Half of the owners (6 out of 12) said “It's like night and day.” Among them, three owners had dogs that were only “improved.” Those three patients were qualified as “greatly improved” by the owners but only classified as “improved” according to the scoring system described herein. In other words, according to the owners, 25% of dogs were considered “cured” and all others were “greatly improved.” One bitch, an obese fila Brasileiro who was “improved,” relapsed 7 mo after the surgery. A second surgery with the same technique was performed. The first tape was not broken, but another tape was placed anyway. After, the dog was considered “cured” and remained so at the second evaluation 5 mo after the second surgery.
At the time of the second evaluation, no adverse effects had been reported by the owners. Although two dogs did require a second surgery, there had been no failures and no need for additional medication. The complete cure rate was 33% (4 out of 12 dogs), and the worst outcome was dogs that had only rare episodes of urine loss. Six owners (50%) were “very satisfied,” and the rest (50%) were “satisfied.” No owner was dissatisfied. According to the owners, their dog's quality of life was improved in all cases. Episiotomy was spontaneously reported as an inconvenience by three owners (25%).
At the time of the third evaluation in January 2012 (median follow-up period was 48 mo; mean, 41 mo; range, 12–70 mo), seven dogs had died. Among them, the two bitches described as “cured” remained “cured” until the time of their death. Three bitches described as “greatly improved” remained “greatly improved” until the time of their death. On average, 29 mo after surgery, sporadic leakage reappeared at the end of the lives of the remaining two bitches. Among the five surviving dogs, the dog described as “cured” at the second evaluation was still “cured” 58 mo postsurgically. For the other four surviving dogs, incontinence reappeared sporadically, a few mo/yr, and a few times/wk. For those four dogs, medical treatment with either phenylpropanolamine (three cases) or estriol (one case) was effective, but two owners (16%) were “unsatisfied” at the time of that evaluation. Among those four dogs, two dogs had fistulas appear on the belly at the path of the tape 28 and 32 mo after surgery. The tapes were removed through a small incision, and culture revealed contamination with Escherichia coli in those two cases. The fistula disappeared after the tape was pulled away and following antibiotic therapy with cephalexin. Sporadic leakage reappeared in those two cases.
At the time of the fourth evaluation in January 2013, the results were the same as at the third evaluation (median follow-up period, 52 mo; mean, 46 mo; range, 12–82 mo).
Discussion
The epidemiologic characteristics of this group are consistent with those previously described. All the dogs in this study had a body weight >25 kg, with a median weight of 30 kg. As previously reported, large dogs have high risk of spay incontinence.2,14,16 Breed representation is also consistent with the literature in that Doberman pinschers (25%), Labrador retrievers (25%), and boxers (17%) are widely represented.2,16,17 The interval between spay and the onset of incontinence is shorter in this study (1.7 yr) than in another study (2.9 yr).2 As in all other reports, incontinence during sleep is common.
A commercial TVT-O kitc consists of a section of polypropylene mesh 40 cm × 1 cm covered by a plastic sheath attached to two needles and two disposable stainless steel helical passers specific for the right and left sides. This device costs about US$650, excluding taxes. In a country where the majority of human patients have no health insurance, investigators suggested making tape from a piece of polypropylene meshd.18,19 Considering that a TVT-O system would also be too expensive for many dog owners, the study authors hypothesized that a rudimentary device made from a simple Reverdin needle and nylon tape would be enough to restore continence. The needle costs $1 and the tape costs $3.
In the standard TVT-O technique, the two free tape ends are cut flush with the skin without fixation. The tape of the TVT-O system is composed of knitted filaments of extruded polypropylene strands that allow the tape to be anchored in the surrounding tissues. The macroporous nature of the tape also allows tissue ingrowth and rapid fibrous fixation. Nylon tape does not have those properties. To avoid nylon tape slippage in this study, the authors knotted the ends of the tape under the skin.
The surgical procedure reported herein appeared to be safe because no major intraoperative complications were encountered. In one study using 12 cadavers and 2 live, continent, spayed female beagle dogs that underwent the precisely analogous procedure used in humans, the tape was found to be a safe distance from arteries, veins, vessels, nerves, the urethra, and bladder.15 In the current study, most cases, it was easy to find the obturator foramen. Difficulty finding the left obturator foramen was probably due to an inappropriate hand movement by the right-handed surgeon. The procedure is relatively fast, with a median surgical time of 45 min (mean, 50 min; range, 35–70 mo), similar to the case series published on the TVT-O procedure in female dogs (mean, 55 min; range, 35–70 min).14 Unlike the procedure in women, the need for an episiotomy increases operating time.
Seven dogs in the current study developed micturition disorders in the immediate postsurgical period. The Great Dane developed severe dysuria due to excessive tension of the tape. The other six cases were not associated with urinary retention. The study authors believe that dysuria is inherent to the proposed technique. Contrary to the original technique, slight tension was introduced. In the study authors' opinion, the bitches included in this case series became continent because they become slightly dysuric by increasing urethral resistance rather than the tape playing the role of support. Micturition disorders (and continence) are especially pronounced the morning following surgery because of the inflammation of the urethra due to surgery.
In the single case series using the TVT-O procedure in female dogs, the technique was effective in six of seven dogs. Follow up ranged from 7 to 15 mo (mean, 11.3 mo) and >12 mo in five dogs.14 The median follow up in the present case series was 52 mo (mean, 46 mo; range, 12–82 mo). According to the owners at the time of the second evaluation (on average 21 mo postsurgically and sometimes after a second surgery), all dogs had their incontinence “cured” or “greatly improved,” and none needed adjuvant therapy. Those results are remarkable because the dogs included in this study all presented with severe incontinence in that incontinence was frequent and two dogs leaked urine constantly, even when walking. Dogs lost not just drops of urine but what was often reported as puddles. The long-term outcome is not as promising. At the third evaluation (on average, 41 mo postsurgically), 50% of the bitches had the same results as previously, but the other 50% had leakage that reappeared sporadically. Nonetheless, incontinence was always less pronounced than before surgery, and all those cases were improved with medical treatment.
In light of the long follow-up period in this study, it was possible to identify a late complication: the appearance of a fistula on the path of the tape in two bitches. Those fistulas were identified 28 and 32 mo postsurgically and Escherichia coli was identified. The first hypothesis is that the tape was contaminated when it was passed through the vagina. The most effective means of avoiding contamination is to use a tape protected by a disposable plastic sleeve that is removed after placement (as is the case with the commercial product). Another important step is to suture the suburethral vaginal incision in a scrupulous fashion. The second hypothesis is rejection if the tape is not sufficiently inert. A polypropylene tape would have been preferable because it has been shown to be well tolerated in dogs.14
Conclusion
The described TVT-O technique has the potential to supplant colposuspension in the female dog, as in humans. The variant of the TVT-O technique presented herein is safe, effective, and more economical than the standard TVT-O technique and could constitute an attractive alternative. Nonetheless, the described technique could be associated with an immediate postoperative dysuria, delayed fistula formation, and a partial recurrence of urine leakage.
A 1 cm vertical midline incision is made through the whole thickness of the vaginal wall beginning 1 cm proximal to the urethral meatus.
The needle is introduced through the vaginal incision at a 45°angle to the sagittal plane then directed craniolaterally, dorsally to the dorsal surface of the ischiopubic bone, keeping the tip in contact with that bone.
The needle is advanced along the bone until a loss of resistance marks the caudal boundary of the obturator foramen. The needle is then advanced along a curved path until the skin is first deformed then penetrated on the midline.
The same procedure is performed on the other side with the other end of the tape using the same needle. Both free ends of the tape exit the body at approximately the same location.
The middle of the tape is laid flat against the urethra to maximize contact between the tape and the urethra.
Both emergent free ends of the tape are simultaneously pulled to remove slack without introducing tension. Traction is stopped when the tape makes contact with the urethra, which is as soon as the urinary catheter begins to move. It is important to not compress the urethra by applying too much tension to the tape. The urinary catheter must be able to move without resistance.
The free ends of the tape are knotted together leaving a 1 cm space between the double knot and the abdomen. The double knot is then buried in the subcutaneous tissue, and the skin incision is closed.
The tape retains its O-shape, located in the distal third of the urethra, just proximal to the urethral meatus.
Contributor Notes
