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CASE REPORT
Surgical treatment of a duplicated and ectopic ureter in a dog M. Newman and B. Landon University Veterinary Teaching Hospital – Sydney, University of Sydney, Camperdown, NSW 2050, Australia Dr. B. Landon’s current address is Landon Veterinary Specialists, 41 Eng Kong Terrace, Eng Kong Park 599013, Singapore
An eight-month old female bull mastiff was referred for evaluation of urinary incontinence. Contrastenhanced computed tomography identified complete duplication of the left ureter with ectopic insertion of the duplicate ureter into the proximal urethra. Ureteroneocystostomy was performed, which improved but did not resolve urinary continence. To the authors’ knowledge, this report details only the second reported case of duplicated ectopic ureter in the dog and the first documenting surgical reimplantation; thus, double-system ureteral ectopia should be considered as a possible differential diagnosis for urinary incontinence.
Journal of Small Animal Practice (2014) 55, 475–478 DOI: 10.1111/jsap.12227 Accepted: Accepted: 22 March 2014; Published online: 30 April 2014
INTRODUCTION Ureteral ectopia is a congenital abnormality with termination of one or both ureters into an ectopic location (McLoughlin & Chew 2000). Duplication of a ureter is rarely reported in the dog, with only three cases in the veterinary literature (O’Handley et al. 1979, Esterline et al. 2005, Novellas et al. 2013). Duplication with ectopia is rarer still, having been described only once in the dog; however, it is a common finding in human patients (Fernbach et al. 1997).
REPORT An eight-month old entire female bull mastiff was presented for evaluation of urinary incontinence. The dog was reported to have dribbled urine since eight weeks of age, although normal urination was observed. A treatment trial of 1 mg/kg phenylpropanolamine (Propalin; Vetoquinol) orally twice a day had been prescribed with minimal response. On presentation, the dog was bright, alert and responsive; general physical examination findings were unremarkable except for perivulvar dermatitis. Urinalysis obtained via cystocentesis revealed moderately concentrated urine (specific gravity 1·022) with normal dipstick and inactive sediment. Serum urea and creatinine concentrations were within their respective reference intervals. The patient was anaesthetised for vaginoscopy and diagnostic imaging; a persistent hymen was seen and manually dilated. Contrast-enhanced computed tomography was performed using a 16-slice helical scanner and administration of 0·4 mg/kg iohexol (Omnipaque; GE Healthcare) intravenously (iv); images were Journal of Small Animal Practice
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Vol 55
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September 2014
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acquired before and at 1, 5, 9 and 13 minutes post-administration. This demonstrated a third ureter, arising from the cranial pole of the left kidney and running parallel to the left ureter (Fig 1). This third ureter arose from the cranial calyces of the left kidney independent from the left renal pelvis. The insertion of the third ureter was not directly visualised; however, it could be seen travelling extramurally to the bladder, and continuing in close apposition to the dorsal urethra before termination of the contrast. A ventral midline exploratory coeliotomy with a ventral cystotomy and proximal urethrotomy were performed. The most cranial 5 mm of pubis was removed with rongeurs to improve exposure of the urethra. The normal ureteral openings were identified in the trigone, and the wide orifice of the aberrant ureter was seen on the dorsal surface of the pelvic urethra, 40 mm distal to the bladder neck (Fig 2). An 8Fr urinary catheter was introduced into the ectopic ureter from distal to proximal, to allow identification of its course. The ectopic ureter ran parallel to the left ureter from the renal pelvis throughout the retroperitoneal space within a common external layer, and diverged in the lateral ligament of the bladder to run beneath the serosa of the bladder and urethra until termination in the pelvic urethra (Fig 3). As the ureter was contained only within the serosa of the bladder, it was determined to be most similar in morphology to an extramural ectopic ureter. The ectopic ureter was double ligated and transected at its insertion, and freed to the level of divergence from the normal ureter. Ureteroneocystostomy was performed so that the ectopic ureter was reimplanted into the bladder cranial to the trigone, and secured with interrupted sutures of 5-0 polyglactin 910. An 8Fr Foley urethral catheter was placed. At closure, urine flow at the new orifice was seen.
© 2014 British Small Animal Veterinary Association
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M. Newman & B. Landon
A
FIG 2. The lumen of the urethra following ventral cystotomy and urethrotomy (the dashed lines demarcate the urethral margins). Cranial is to the top of the image. The trigone and normal ureteric orifices are not seen in this image. The opening to the anomalous third ureter can be visualised as a wide opening on the dorsal surface of the urethra (arrow)
B
C FIG 1. Contrast-enhanced computed tomography. (A) The aberrant ureter can be seen draining the calyces of the cranial pole of the kidney (white arrow), independent of the renal pelvis proper. (B) The confluence of the cranial calyces within the kidney (red circle), which gives rise to the third ureter. This was separate to the renal pelvis. (C) The third ureter can be seen coursing through the abdomen adjacent to the normal left ureter, and can be seen adjacent to the urethra before termination (white arrowheads)
FIG 3. The left side of the serosal surface of the bladder, with the two left ureters visualised from the external surface. The duplicate ureter (blue outlines) can be seen diverging from the main ureter (green outlines) under the serosa of the bladder. Cranial is to the right of the image
The urethral catheter was removed 48 hours post-operatively and the patient was observed to void normally, with some intermittent dribbling. Intra-operative urinary culture revealed a growth of Escherichia coli, and culture of the catheter tip following
removal revealed a growth of Staphylococcus intermedius. Both isolates were sensitive to amoxicillin-clavulanate. The dog was discharged on 20 mg/kg amoxicillin-clavulanate (Clavulox; Pfizer) orally twice a day for 10 days, 2 mg/kg carprofen (Rimadyl;
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Journal of Small Animal Practice
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Duplicated and ectopic ureter in a dog
Pfizer) orally twice a day for 5 days and 1·5 mg/kg tramadol (Tramal; CSL) orally twice a day for 5 days. At the last follow-up, 10 months post-operatively, the patient was reported to have mild urinary incontinence, which was responsive to twice daily administration of phenylpropanolamine. Without medication, continence was felt to be improved compared to pre-operatively.
DISCUSSION Ureteral duplication with ectopia has been reported only once previously in the dog (Novellas et al. 2013), and duplication without ectopia twice before (O’Handley et al. 1979, Esterline et al. 2005). Ectopic ureters in human patients are most commonly associated with a duplex kidney and ureter, such as in this case, with single-system ureteral ectopia being the exception (Ahmed & Barker 1992, El Ghoneimi et al. 1996, Fernbach et al. 1997). The mammalian urinary system develops in three overlapping stages – the pronephros, the mesonephros and the metanephros, with the renal cortex arising from the metanephric blastema. The metanephric duct arises as the metanephric diverticulum (or ureteric bud) from the mesonephric (Wolffian) duct; it is this which will ultimately become the ureter, renal pelvis and renal medulla. As the metanephric duct migrates cranially to meet the metanephros, the growing urinary bladder will incorporate the caudal mesonephric duct. A cuff of surrounding mesenchymal cells is incorporated into the bladder with the caudal mesonephric duct; it is these cells which will be responsible for formation of the trigone and internal urethral sphincter. The mesonephric ducts persist in the male as the epididymis, vasa deferentia, and seminal vesicles, and regress in the female. Some mesonephric duct remnants will persist in the female as Gartner’s glands, which are incorporated into the reproductive structures derived from the paramesonephric (Mullerian) duct (Owen 1973, Tanagho 1976, Stahl et al. 2006). In single-system ureteral ectopia, the metanephric diverticulum arises more cranially on the mesonephric duct. The caudal mesonephric duct is then delayed in its incorporation into the growing urinary bladder. The insertion site becomes more distal, and may insert into the urethra, seminal vesicles, or vasa deferentia in the male; or in the female in the urethra or reproductive tract in the region of Gartner’s glands (Owen 1973). In a duplex ectopia, two separate diverticuli arise from the mesonephric duct, and each will independently migrate cranially to meet the metanephros. Thus two independent calycal systems are formed. As the urinary bladder incorporates them, the ureter that arose most caudad on the mesonephric duct is incorporated in a relatively orthotopic location. The more cranial of the two will be delayed in union, and insert in an ectopic location. Thus, the caudal pole of the kidney is drained by the orthotopic ureter, while the cranial pole is drained by the other, known as the Weigert–Meyer law (Tanagho 1976, Stahl et al. 2006). Ureteral duplication has, to the authors’ knowledge, been described only three times in the dog. O’Handley et al. (1979) Journal of Small Animal Practice
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described renal and ureteral duplication in a male English bulldog with recurrent urinary tract infections. Two right ureters were present, with the cranial pole ureter inserting into the trigone in a slightly more caudal location than the caudal pole ureter. Esterline et al. (2005) described ureteral duplication in a male dog with signs of upper urinary tract infection. A blind-ended ureter extended from the cranial pole of the kidney to the caudal abdomen, while the normal ureter drained the caudal pole; this case was treated by nephroureterectomy. More recently, Novellas et al. (2013) described duplicated ureter with ectopic insertion in a nine-year old Labrador retriever with recurrent urinary tract infections and incontinence; this was treated with resection of the aberrant ureter. This case is of note as it appears not to follow the Weigert–Meyer law. Ureteral duplication has also been reported in the cat, pigs and alpaca (Benko 1969, Cardwell & Thorne 1999, Ghantous & Crawford 2006). The gross anatomy of duplication appears to follow the Weigert-Meyer law in all reports, with the sole exception of that reported by Novellas et al. (2013). Surgical treatment for ureteral ectopia is generally determined by morphology. Intramural ectopia may be treated by neoureterostomy or cystoscopic-guided laser ablation (McLoughlin & Chew 2000, Mayhew et al. 2006, Berent et al. 2008, Smith et al. 2010, Ho et al. 2011). Ureteroneocystostomy was elected in the present case as although the ureter was not completely extramural, a stoma could not safely be created via neoureterostomy. As there appeared to be no connection between the two calycal systems in the left kidney based on the pre-operative computed tomography (CT), resection of the aberrant ureter would not have been applicable, as performed by Novellas et al. (2013); ureteral resection and partial nephrectomy would have been required to avoid a hydronephrotic cranial pole. Human patients with duplicated ureters may be treated by upper pole partial nephrectomy if hydronephrosis is present; however, parenchymasparing procedures such as ureteroneocystostomy, ureteroureterostomy and ureteropyelostomy are preferred (Ahmed & Barker 1992, El Ghoneimi et al. 1996). Regardless of technique, surgical treatment for ureteral ectopia is often unrewarding¸ with incontinence persisting in 45 to 68% of cases (McLoughlin & Chew 2000, Berent et al. 2008, Ho et al. 2011, Mayhew et al. 2006, Smith et al. 2010, McLaughlin & Miller 1991). Persistent incontinence is thought to be a result of concurrent urethral sphincter mechanism incompetence (McLaughlin & Miller 1991). The development of the ureters and the trigone are inextricably linked; disordered formation of the smooth muscle of the urethral sphincter may occur in conjunction with ureteral ectopia (Stahl et al. 2006). Urethral pressure profilometry is the method of choice to diagnose urethral sphincter abnormalities. Lane et al. (1995) reported abnormalities consistent with altered urethral sphincter function in 78% of dogs with ureteral ectopia. Similarly, Koie et al. (2000) found lowered urethral closing pressures in four dogs with ureteral ectopia, compared to controls. This is consistent with the increased response rate following ectopic ureter surgery when sphincter-augmenting medications are instituted.
© 2014 British Small Animal Veterinary Association
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M. Newman & B. Landon
Congenital abnormalities of the vagina and vestibule are commonly seen in conjunction with ureteral ectopia. Samii et al. (2003) diagnosed concurrent vestibulovaginal stenosis in 100% of dogs examined via cystoscopy; likewise Cannizzo et al. (2003) reported a range of vestibulovaginal abnormalities in 23 of 23 dogs examined cystoscopically. The significance of vestibulovaginal stenosis in urinary incontinence is unclear. The area of stenosis allows urine to pool, predisposing to urinary tract infections and ongoing lower urinary tract signs; however, Holt (1985) suggested that vestibulovaginal stenosis does not worsen the prognosis for continence. In conclusion, this case details the first known report of surgical reimplantation of a duplicated and ectopic ureter in the dog. While rare, duplicate ureters should be considered as a differential diagnosis for dogs with urinary incontinence and suspected ureteral ectopia. Surgical treatment in this case improved, but did not eliminate, urinary incontinence. Acknowledgements The authors thank Dr. Manuel Pinilla for his diagnostic imaging expertise in this case. Conflict of interest None of the authors of this article has a financial or personal relationship with other people or organisations that could inappropriately influence or bias the content of the paper. References Ahmed, S. & Barker, A. (1992) Single-system ectopic ureters: a review of 12 cases. Journal of Pediatric Surgery 27, 491-496 Benko, L. (1969) Cases of bilateral and unilateral duplication of ureters in the pig. Veterinary Record 84, 139-140 Berent, A. C., Mayhew, P. D. & Porat-Mosenco, Y. (2008) Use of cystoscopic-guided laser ablation for treatment of intramural ureteral ectopia in male dogs: four cases (2006-2007). Journal of American Veterinary Medical Association 232, 1026-1034 Cannizzo, K. L., Mcloughlin, M. A., Mattoon, J. S., et al. (2003) Evaluation of transurethral cystoscopy and excretory urography for diagnosis of ectopic ureters in
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female dogs: 25 cases (1992-2000). Journal of American Veterinary Medical Association 223, 475-481 Cardwell, J. M. & Thorne, M. J. (1999) Hydronephrosis and ureteral duplication in a young alpaca. Veterinary Record 145, 104-107 El Ghoneimi, A., Miranda, J., Truong, T., et al. (1996) Ectopic ureter with complete ureteric duplication: conservative surgical management Journal of Pediatric Surgery 31, 467-472 Esterline, M. L., Biller, D. S. & Sicard, G. K. (2005) Ureteral duplication in a dog. Veterinary Radiology and Ultrasound 46, 485-489 Fernbach, S. K., Feinstein K. A., Spencer, K., et al. (1997) Ureteral duplication and its complications. Radiographics 17, 109-127 Ghantous, S. N. & Crawford, J. (2006) Double ureters with ureteral ectopia in a domestic shorthair cat. Journal of American Animal Hospital Association 42, 462-466 Ho, L. K., Troy, G. C. & Waldron, D. R. (2011) Clinical outcomes of surgically managed ectopic ureters in 33 dogs. Journal of American Animal Hospital Association 47, 196-202 Holt, P. E. (1985) Importance of urethral length, bladder neck position, and vestibulovaginal stenosis in sphincter mechanism incompetence in the incontinent bitch. Research in Veterinary Science 39, 364-372 Koie, H., Yamaya, Y. & Sakai, T. (2000) Four cases of lowered urethral pressure in canine ectopic ureter. Journal of Veterinary Medical Science 62, 1221-1222 Lane, I. F., Lappin, M. R. & Seim, H. B. (1995) Evaluation of results of preoperative urodynamic measurements in nine dogs with ectopic ureters. Journal of American Veterinary Medical Association 206, 1348-1357 Mayhew, P. D., Lee, K. C., Gregory, S. P., et al. (2006) Comparison of two surgical techniques for management of intramural ureteral ectopia in dogs: 36 cases (1994-2004). Journal of American Veterinary Medical Association 229, 389-393 McLaughlin, R. & Miller, C. W. (1991) Urinary incontinence after surgical repair of ureteral ectopia in dogs. Veterinary Surgery 20, 100-103 McLoughlin, M. A. & Chew, D. J. (2000) Diagnosis and surgical management of ectopic ureters. Clinical Techniques in Small Animal Practice 15, 17-24 Novellas, R., Stone, J., Pratschke K., et al. (2013) Duplicated ectopic ureter in a nine-year old labrador. Journal of Small Animal Practice [Epub ahead of print] 4 April 2013 DOI: 10.1111/jsap.12056 O’Handley, P., Carrig, C. B. & Walshaw, R. (1979). Renal and ureteral duplication in a dog. Journal of American Veterinary Medical Association 174, 484-487 Owen, R. (1973) Canine ureteral ectopia – a review. 1: embryology and aetiology. Journal of Small Animal Practice 14, 407-417 Samii, V. F., Mcloughlin, M. A., Mattoon, J. S., et al. (2004) Digital fluoroscopic excretory urography, digital fluoroscopic urethrography, helical computed tomography, and cystoscopy in 24 dogs with suspected ureteral ectopia. Journal of Veterinary Internal Medicine 18, 271-281 Smith, A. L., Radlinsky, M. G., Rawlings, C. A. (2010). “Cystoscopic Diagnosis And Treatment Of Ectopic Ureters In Female Dogs: 16 Cases (2005-2008)”. J Am Vet Med Assoc 237(2):191-195 Stahl, D. A., Koul, H. K., Chacko, J. K., et al. (2006) Congenital anomalies of the kidney and urinary tract (CAKUT): a review of cell signalling processes in ureteral development. Journal of Pediatric Urology 2, 2-9 Tanagho, E. A. (1976) Embryologic basis for ureteral anomalies: a hypothesis. Urology 7, 451-464
Journal of Small Animal Practice
•
Vol 55
•
September 2014
•
© 2014 British Small Animal Veterinary Association
CASE REPORT
Surgical treatment of a duplicated and ectopic ureter in a dog M. Newman and B. Landon University Veterinary Teaching Hospital – Sydney, University of Sydney, Camperdown, NSW 2050, Australia Dr. B. Landon’s current address is Landon Veterinary Specialists, 41 Eng Kong Terrace, Eng Kong Park 599013, Singapore
An eight-month old female bull mastiff was referred for evaluation of urinary incontinence. Contrastenhanced computed tomography identified complete duplication of the left ureter with ectopic insertion of the duplicate ureter into the proximal urethra. Ureteroneocystostomy was performed, which improved but did not resolve urinary continence. To the authors’ knowledge, this report details only the second reported case of duplicated ectopic ureter in the dog and the first documenting surgical reimplantation; thus, double-system ureteral ectopia should be considered as a possible differential diagnosis for urinary incontinence.
Journal of Small Animal Practice (2014) 55, 475–478 DOI: 10.1111/jsap.12227 Accepted: Accepted: 22 March 2014; Published online: 30 April 2014
INTRODUCTION Ureteral ectopia is a congenital abnormality with termination of one or both ureters into an ectopic location (McLoughlin & Chew 2000). Duplication of a ureter is rarely reported in the dog, with only three cases in the veterinary literature (O’Handley et al. 1979, Esterline et al. 2005, Novellas et al. 2013). Duplication with ectopia is rarer still, having been described only once in the dog; however, it is a common finding in human patients (Fernbach et al. 1997).
REPORT An eight-month old entire female bull mastiff was presented for evaluation of urinary incontinence. The dog was reported to have dribbled urine since eight weeks of age, although normal urination was observed. A treatment trial of 1 mg/kg phenylpropanolamine (Propalin; Vetoquinol) orally twice a day had been prescribed with minimal response. On presentation, the dog was bright, alert and responsive; general physical examination findings were unremarkable except for perivulvar dermatitis. Urinalysis obtained via cystocentesis revealed moderately concentrated urine (specific gravity 1·022) with normal dipstick and inactive sediment. Serum urea and creatinine concentrations were within their respective reference intervals. The patient was anaesthetised for vaginoscopy and diagnostic imaging; a persistent hymen was seen and manually dilated. Contrast-enhanced computed tomography was performed using a 16-slice helical scanner and administration of 0·4 mg/kg iohexol (Omnipaque; GE Healthcare) intravenously (iv); images were Journal of Small Animal Practice
•
Vol 55
•
September 2014
•
acquired before and at 1, 5, 9 and 13 minutes post-administration. This demonstrated a third ureter, arising from the cranial pole of the left kidney and running parallel to the left ureter (Fig 1). This third ureter arose from the cranial calyces of the left kidney independent from the left renal pelvis. The insertion of the third ureter was not directly visualised; however, it could be seen travelling extramurally to the bladder, and continuing in close apposition to the dorsal urethra before termination of the contrast. A ventral midline exploratory coeliotomy with a ventral cystotomy and proximal urethrotomy were performed. The most cranial 5 mm of pubis was removed with rongeurs to improve exposure of the urethra. The normal ureteral openings were identified in the trigone, and the wide orifice of the aberrant ureter was seen on the dorsal surface of the pelvic urethra, 40 mm distal to the bladder neck (Fig 2). An 8Fr urinary catheter was introduced into the ectopic ureter from distal to proximal, to allow identification of its course. The ectopic ureter ran parallel to the left ureter from the renal pelvis throughout the retroperitoneal space within a common external layer, and diverged in the lateral ligament of the bladder to run beneath the serosa of the bladder and urethra until termination in the pelvic urethra (Fig 3). As the ureter was contained only within the serosa of the bladder, it was determined to be most similar in morphology to an extramural ectopic ureter. The ectopic ureter was double ligated and transected at its insertion, and freed to the level of divergence from the normal ureter. Ureteroneocystostomy was performed so that the ectopic ureter was reimplanted into the bladder cranial to the trigone, and secured with interrupted sutures of 5-0 polyglactin 910. An 8Fr Foley urethral catheter was placed. At closure, urine flow at the new orifice was seen.
© 2014 British Small Animal Veterinary Association
475
M. Newman & B. Landon
A
FIG 2. The lumen of the urethra following ventral cystotomy and urethrotomy (the dashed lines demarcate the urethral margins). Cranial is to the top of the image. The trigone and normal ureteric orifices are not seen in this image. The opening to the anomalous third ureter can be visualised as a wide opening on the dorsal surface of the urethra (arrow)
B
C FIG 1. Contrast-enhanced computed tomography. (A) The aberrant ureter can be seen draining the calyces of the cranial pole of the kidney (white arrow), independent of the renal pelvis proper. (B) The confluence of the cranial calyces within the kidney (red circle), which gives rise to the third ureter. This was separate to the renal pelvis. (C) The third ureter can be seen coursing through the abdomen adjacent to the normal left ureter, and can be seen adjacent to the urethra before termination (white arrowheads)
FIG 3. The left side of the serosal surface of the bladder, with the two left ureters visualised from the external surface. The duplicate ureter (blue outlines) can be seen diverging from the main ureter (green outlines) under the serosa of the bladder. Cranial is to the right of the image
The urethral catheter was removed 48 hours post-operatively and the patient was observed to void normally, with some intermittent dribbling. Intra-operative urinary culture revealed a growth of Escherichia coli, and culture of the catheter tip following
removal revealed a growth of Staphylococcus intermedius. Both isolates were sensitive to amoxicillin-clavulanate. The dog was discharged on 20 mg/kg amoxicillin-clavulanate (Clavulox; Pfizer) orally twice a day for 10 days, 2 mg/kg carprofen (Rimadyl;
476
Journal of Small Animal Practice
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Vol 55
•
September 2014
•
© 2014 British Small Animal Veterinary Association
Duplicated and ectopic ureter in a dog
Pfizer) orally twice a day for 5 days and 1·5 mg/kg tramadol (Tramal; CSL) orally twice a day for 5 days. At the last follow-up, 10 months post-operatively, the patient was reported to have mild urinary incontinence, which was responsive to twice daily administration of phenylpropanolamine. Without medication, continence was felt to be improved compared to pre-operatively.
DISCUSSION Ureteral duplication with ectopia has been reported only once previously in the dog (Novellas et al. 2013), and duplication without ectopia twice before (O’Handley et al. 1979, Esterline et al. 2005). Ectopic ureters in human patients are most commonly associated with a duplex kidney and ureter, such as in this case, with single-system ureteral ectopia being the exception (Ahmed & Barker 1992, El Ghoneimi et al. 1996, Fernbach et al. 1997). The mammalian urinary system develops in three overlapping stages – the pronephros, the mesonephros and the metanephros, with the renal cortex arising from the metanephric blastema. The metanephric duct arises as the metanephric diverticulum (or ureteric bud) from the mesonephric (Wolffian) duct; it is this which will ultimately become the ureter, renal pelvis and renal medulla. As the metanephric duct migrates cranially to meet the metanephros, the growing urinary bladder will incorporate the caudal mesonephric duct. A cuff of surrounding mesenchymal cells is incorporated into the bladder with the caudal mesonephric duct; it is these cells which will be responsible for formation of the trigone and internal urethral sphincter. The mesonephric ducts persist in the male as the epididymis, vasa deferentia, and seminal vesicles, and regress in the female. Some mesonephric duct remnants will persist in the female as Gartner’s glands, which are incorporated into the reproductive structures derived from the paramesonephric (Mullerian) duct (Owen 1973, Tanagho 1976, Stahl et al. 2006). In single-system ureteral ectopia, the metanephric diverticulum arises more cranially on the mesonephric duct. The caudal mesonephric duct is then delayed in its incorporation into the growing urinary bladder. The insertion site becomes more distal, and may insert into the urethra, seminal vesicles, or vasa deferentia in the male; or in the female in the urethra or reproductive tract in the region of Gartner’s glands (Owen 1973). In a duplex ectopia, two separate diverticuli arise from the mesonephric duct, and each will independently migrate cranially to meet the metanephros. Thus two independent calycal systems are formed. As the urinary bladder incorporates them, the ureter that arose most caudad on the mesonephric duct is incorporated in a relatively orthotopic location. The more cranial of the two will be delayed in union, and insert in an ectopic location. Thus, the caudal pole of the kidney is drained by the orthotopic ureter, while the cranial pole is drained by the other, known as the Weigert–Meyer law (Tanagho 1976, Stahl et al. 2006). Ureteral duplication has, to the authors’ knowledge, been described only three times in the dog. O’Handley et al. (1979) Journal of Small Animal Practice
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Vol 55
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September 2014
•
described renal and ureteral duplication in a male English bulldog with recurrent urinary tract infections. Two right ureters were present, with the cranial pole ureter inserting into the trigone in a slightly more caudal location than the caudal pole ureter. Esterline et al. (2005) described ureteral duplication in a male dog with signs of upper urinary tract infection. A blind-ended ureter extended from the cranial pole of the kidney to the caudal abdomen, while the normal ureter drained the caudal pole; this case was treated by nephroureterectomy. More recently, Novellas et al. (2013) described duplicated ureter with ectopic insertion in a nine-year old Labrador retriever with recurrent urinary tract infections and incontinence; this was treated with resection of the aberrant ureter. This case is of note as it appears not to follow the Weigert–Meyer law. Ureteral duplication has also been reported in the cat, pigs and alpaca (Benko 1969, Cardwell & Thorne 1999, Ghantous & Crawford 2006). The gross anatomy of duplication appears to follow the Weigert-Meyer law in all reports, with the sole exception of that reported by Novellas et al. (2013). Surgical treatment for ureteral ectopia is generally determined by morphology. Intramural ectopia may be treated by neoureterostomy or cystoscopic-guided laser ablation (McLoughlin & Chew 2000, Mayhew et al. 2006, Berent et al. 2008, Smith et al. 2010, Ho et al. 2011). Ureteroneocystostomy was elected in the present case as although the ureter was not completely extramural, a stoma could not safely be created via neoureterostomy. As there appeared to be no connection between the two calycal systems in the left kidney based on the pre-operative computed tomography (CT), resection of the aberrant ureter would not have been applicable, as performed by Novellas et al. (2013); ureteral resection and partial nephrectomy would have been required to avoid a hydronephrotic cranial pole. Human patients with duplicated ureters may be treated by upper pole partial nephrectomy if hydronephrosis is present; however, parenchymasparing procedures such as ureteroneocystostomy, ureteroureterostomy and ureteropyelostomy are preferred (Ahmed & Barker 1992, El Ghoneimi et al. 1996). Regardless of technique, surgical treatment for ureteral ectopia is often unrewarding¸ with incontinence persisting in 45 to 68% of cases (McLoughlin & Chew 2000, Berent et al. 2008, Ho et al. 2011, Mayhew et al. 2006, Smith et al. 2010, McLaughlin & Miller 1991). Persistent incontinence is thought to be a result of concurrent urethral sphincter mechanism incompetence (McLaughlin & Miller 1991). The development of the ureters and the trigone are inextricably linked; disordered formation of the smooth muscle of the urethral sphincter may occur in conjunction with ureteral ectopia (Stahl et al. 2006). Urethral pressure profilometry is the method of choice to diagnose urethral sphincter abnormalities. Lane et al. (1995) reported abnormalities consistent with altered urethral sphincter function in 78% of dogs with ureteral ectopia. Similarly, Koie et al. (2000) found lowered urethral closing pressures in four dogs with ureteral ectopia, compared to controls. This is consistent with the increased response rate following ectopic ureter surgery when sphincter-augmenting medications are instituted.
© 2014 British Small Animal Veterinary Association
477
M. Newman & B. Landon
Congenital abnormalities of the vagina and vestibule are commonly seen in conjunction with ureteral ectopia. Samii et al. (2003) diagnosed concurrent vestibulovaginal stenosis in 100% of dogs examined via cystoscopy; likewise Cannizzo et al. (2003) reported a range of vestibulovaginal abnormalities in 23 of 23 dogs examined cystoscopically. The significance of vestibulovaginal stenosis in urinary incontinence is unclear. The area of stenosis allows urine to pool, predisposing to urinary tract infections and ongoing lower urinary tract signs; however, Holt (1985) suggested that vestibulovaginal stenosis does not worsen the prognosis for continence. In conclusion, this case details the first known report of surgical reimplantation of a duplicated and ectopic ureter in the dog. While rare, duplicate ureters should be considered as a differential diagnosis for dogs with urinary incontinence and suspected ureteral ectopia. Surgical treatment in this case improved, but did not eliminate, urinary incontinence. Acknowledgements The authors thank Dr. Manuel Pinilla for his diagnostic imaging expertise in this case. Conflict of interest None of the authors of this article has a financial or personal relationship with other people or organisations that could inappropriately influence or bias the content of the paper. References Ahmed, S. & Barker, A. (1992) Single-system ectopic ureters: a review of 12 cases. Journal of Pediatric Surgery 27, 491-496 Benko, L. (1969) Cases of bilateral and unilateral duplication of ureters in the pig. Veterinary Record 84, 139-140 Berent, A. C., Mayhew, P. D. & Porat-Mosenco, Y. (2008) Use of cystoscopic-guided laser ablation for treatment of intramural ureteral ectopia in male dogs: four cases (2006-2007). Journal of American Veterinary Medical Association 232, 1026-1034 Cannizzo, K. L., Mcloughlin, M. A., Mattoon, J. S., et al. (2003) Evaluation of transurethral cystoscopy and excretory urography for diagnosis of ectopic ureters in
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female dogs: 25 cases (1992-2000). Journal of American Veterinary Medical Association 223, 475-481 Cardwell, J. M. & Thorne, M. J. (1999) Hydronephrosis and ureteral duplication in a young alpaca. Veterinary Record 145, 104-107 El Ghoneimi, A., Miranda, J., Truong, T., et al. (1996) Ectopic ureter with complete ureteric duplication: conservative surgical management Journal of Pediatric Surgery 31, 467-472 Esterline, M. L., Biller, D. S. & Sicard, G. K. (2005) Ureteral duplication in a dog. Veterinary Radiology and Ultrasound 46, 485-489 Fernbach, S. K., Feinstein K. A., Spencer, K., et al. (1997) Ureteral duplication and its complications. Radiographics 17, 109-127 Ghantous, S. N. & Crawford, J. (2006) Double ureters with ureteral ectopia in a domestic shorthair cat. Journal of American Animal Hospital Association 42, 462-466 Ho, L. K., Troy, G. C. & Waldron, D. R. (2011) Clinical outcomes of surgically managed ectopic ureters in 33 dogs. Journal of American Animal Hospital Association 47, 196-202 Holt, P. E. (1985) Importance of urethral length, bladder neck position, and vestibulovaginal stenosis in sphincter mechanism incompetence in the incontinent bitch. Research in Veterinary Science 39, 364-372 Koie, H., Yamaya, Y. & Sakai, T. (2000) Four cases of lowered urethral pressure in canine ectopic ureter. Journal of Veterinary Medical Science 62, 1221-1222 Lane, I. F., Lappin, M. R. & Seim, H. B. (1995) Evaluation of results of preoperative urodynamic measurements in nine dogs with ectopic ureters. Journal of American Veterinary Medical Association 206, 1348-1357 Mayhew, P. D., Lee, K. C., Gregory, S. P., et al. (2006) Comparison of two surgical techniques for management of intramural ureteral ectopia in dogs: 36 cases (1994-2004). Journal of American Veterinary Medical Association 229, 389-393 McLaughlin, R. & Miller, C. W. (1991) Urinary incontinence after surgical repair of ureteral ectopia in dogs. Veterinary Surgery 20, 100-103 McLoughlin, M. A. & Chew, D. J. (2000) Diagnosis and surgical management of ectopic ureters. Clinical Techniques in Small Animal Practice 15, 17-24 Novellas, R., Stone, J., Pratschke K., et al. (2013) Duplicated ectopic ureter in a nine-year old labrador. Journal of Small Animal Practice [Epub ahead of print] 4 April 2013 DOI: 10.1111/jsap.12056 O’Handley, P., Carrig, C. B. & Walshaw, R. (1979). Renal and ureteral duplication in a dog. Journal of American Veterinary Medical Association 174, 484-487 Owen, R. (1973) Canine ureteral ectopia – a review. 1: embryology and aetiology. Journal of Small Animal Practice 14, 407-417 Samii, V. F., Mcloughlin, M. A., Mattoon, J. S., et al. (2004) Digital fluoroscopic excretory urography, digital fluoroscopic urethrography, helical computed tomography, and cystoscopy in 24 dogs with suspected ureteral ectopia. Journal of Veterinary Internal Medicine 18, 271-281 Smith, A. L., Radlinsky, M. G., Rawlings, C. A. (2010). “Cystoscopic Diagnosis And Treatment Of Ectopic Ureters In Female Dogs: 16 Cases (2005-2008)”. J Am Vet Med Assoc 237(2):191-195 Stahl, D. A., Koul, H. K., Chacko, J. K., et al. (2006) Congenital anomalies of the kidney and urinary tract (CAKUT): a review of cell signalling processes in ureteral development. Journal of Pediatric Urology 2, 2-9 Tanagho, E. A. (1976) Embryologic basis for ureteral anomalies: a hypothesis. Urology 7, 451-464
Journal of Small Animal Practice
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Vol 55
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September 2014
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© 2014 British Small Animal Veterinary Association
