Surgical treatment of retroiliac ectopic ureters with secondary hydronephrosis and hydroureter in a dog

Maureen A. Griffin Veterinary Medical Teaching Hospital, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616.

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William T. N. Culp Department of Surgical & Radiological Sciences, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616.

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Matthew J. L. Munro Veterinary Medical Teaching Hospital, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616.

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Carrie A. Palm Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616.

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Mason W. Wanamaker Veterinary Medical Teaching Hospital, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616.

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Abstract

CASE DESCRIPTION

An 8-month-old 41.2-kg (90.6-lb) sexually intact male Dogue de Bordeaux with urinary incontinence and signs of nausea was referred for further evaluation and treatment of bilateral hydronephrosis, hydroureter, and ectopic ureters.

CLINICAL FINDINGS

Clinicopathologic analyses revealed urine specific gravity and serum concentrations of urea nitrogen and creatinine within reference limits. Abdominal ultrasonography and CT revealed unilateral abdominal cryptorchidism, ureters that bilaterally passed dorsal to and appeared compressed by the external iliac arteries (retroiliac ureters), and bilateral hydronephrosis, hydroureter, and ectopic ureters. On CT, minimal uptake of contrast medium by the right kidney indicated either a lack of renal function or ureteral obstruction.

TREATMENT AND OUTCOME

The dog underwent exploratory laparotomy, right ureteronephrectomy, left neoureterocystostomy, bilateral castration, and incisional gastropexy without complication and was discharged 2 days postoperatively. Eleven days after surgery, the dog had improved but continued urinary incontinence, improved left hydronephrosis and hydroureter, and serum concentrations of urea nitrogen and creatinine within reference limits. At 24 months after surgery, the dog was reportedly clinically normal, other than having persistent urinary incontinence.

CLINICAL RELEVANCE

To our knowledge, this was the first report of a dog with retroiliac ureters and compression-induced ureteral obstruction with secondary hydroureter and hydronephrosis. Retroiliac ureters should be considered as a differential diagnosis in young dogs with ureteral obstruction. Our findings indicated that a good outcome was possible for a dog with retroiliac ureters treated surgically; however, the presence of additional congenital anomalies should be considered and may alter the prognosis in dogs with retroiliac ureters.

Abstract

CASE DESCRIPTION

An 8-month-old 41.2-kg (90.6-lb) sexually intact male Dogue de Bordeaux with urinary incontinence and signs of nausea was referred for further evaluation and treatment of bilateral hydronephrosis, hydroureter, and ectopic ureters.

CLINICAL FINDINGS

Clinicopathologic analyses revealed urine specific gravity and serum concentrations of urea nitrogen and creatinine within reference limits. Abdominal ultrasonography and CT revealed unilateral abdominal cryptorchidism, ureters that bilaterally passed dorsal to and appeared compressed by the external iliac arteries (retroiliac ureters), and bilateral hydronephrosis, hydroureter, and ectopic ureters. On CT, minimal uptake of contrast medium by the right kidney indicated either a lack of renal function or ureteral obstruction.

TREATMENT AND OUTCOME

The dog underwent exploratory laparotomy, right ureteronephrectomy, left neoureterocystostomy, bilateral castration, and incisional gastropexy without complication and was discharged 2 days postoperatively. Eleven days after surgery, the dog had improved but continued urinary incontinence, improved left hydronephrosis and hydroureter, and serum concentrations of urea nitrogen and creatinine within reference limits. At 24 months after surgery, the dog was reportedly clinically normal, other than having persistent urinary incontinence.

CLINICAL RELEVANCE

To our knowledge, this was the first report of a dog with retroiliac ureters and compression-induced ureteral obstruction with secondary hydroureter and hydronephrosis. Retroiliac ureters should be considered as a differential diagnosis in young dogs with ureteral obstruction. Our findings indicated that a good outcome was possible for a dog with retroiliac ureters treated surgically; however, the presence of additional congenital anomalies should be considered and may alter the prognosis in dogs with retroiliac ureters.

Introduction

An 8-month-old 41.2-kg (90.6-lb) sexually intact male Dogue de Bordeaux was referred to the University of California-Davis Veterinary Medical Teaching Hospital for further evaluation and treatment of marked right hydronephrosis, moderate left hydronephrosis, bilateral ectopic ureters, and bilateral hydroureter diagnosed ultrasonographically by the referring veterinarian. The dog was initially examined by the referring veterinarian because of an episode of signs of nausea and nonproductive retching. Results of a CBC and serum biochemical analyses performed by the referring veterinarian were within reference limits for a juvenile dog, and abdominal radiography had revealed a mass effect in the right side of the abdomen. The referring veterinarian had recommended that the dog undergo right-sided nephrectomy.

On initial referral evaluation, the dog was bright, alert, and well muscled and had vital signs within reference limits and a body condition score of 4 (on a scale of 1 to 9). The dog had palpably enlarged kidneys, a urinary bladder that was approximately 5 cm in diameter, and a descended left testicle but no right testicle palpable in the scrotum or inguinal region. Other findings on physical examination were maxillary brachygnathia, mild dental calculus, and adult dentition with a persistent deciduous right maxillary first premolar tooth. The remainder of the findings on physical examination were unremarkable. The owners reported that they acquired the dog as a 9-week-old puppy and had noticed mild, intermittent urinary incontinence since then. The urinary incontinence mostly occurred when the dog was sleeping or rising from rest and had improved over the several months prior to the present evaluation. In addition, the owners described no stranguria, hematuria, pollakiuria, dysuria, polyuria, or polydipsia and reported that the dog could urinate normally. The owners also relayed that the dog was not receiving any medications and had a normal appetite and energy level.

The dog's indirect systolic blood pressure was 153 mm Hg (reference range, 90 to 140 mm Hg), and results of serum biochemical analyses were within reference limits, including serum concentrations of urea nitrogen (16 mg/dL; reference range, 11 to 33 mg/dL), creatinine (0.9 mg/dL; reference range, 0.8 to 1.5 mg/dL), and SDMAa (13 μg/dL; reference range, ≤ 16 μg/dL for puppies). Cystocentesis was performed, and urinalysis revealed a urine specific gravity of 1.019 and pH of 6.5. Urine sediments included 0 to 3 WBCs/hpf (reference range, 0 to 3 WBCs/hpf), 3 to 5 RBCs/hpf (reference range, 0 to 2 RBCs/hpf), rare transitional epithelial cells, few mucous strands, and no bacteria. Aerobic bacterial culture performed on a sample of urine yielded no growth.

Abdominal and scrotal ultrasonographyb was performed. The right kidney was markedly enlarged (approx 23 × 11 cm) and hydronephrotic, with loss of any visible renal parenchyma. The right ureter was dilated (up to 4.1 cm in diameter) along its length and terminated within the proximal region of the urethra at the level of the prostate. The left kidney was also hydronephrotic (renal pelvis, approx 1.3 × 3.4 cm) with moderate loss of renal parenchyma (Figure 1). The left ureter was dilated (approx 1 cm in diameter) along its length and appeared to terminate in the region of the trigone. Both ureters appeared to have a retrocaval conformation. On the basis of ultrasonographic evaluation, the ectopic ureteral conformation was determined to have been extramural on the right and intramural on the left. The urinary bladder appeared ultrasonographically normal. The dog's right testicle (approx 3.4-cm sphere) was identified in the right caudal abdominal region ventral to the right ureter and was mildly smaller than the descended left testicle (approx 4.2-cm sphere). The remainder of the findings during ultrasonographic examination were considered clinically normal, and abdominal CT was scheduled to further characterize the multiple anatomic anomalies and assess renal function.

Figure 1
Figure 1

Ultrasonographic (A) and postcontrast CT (B) images of an 8-month-old 41.2-kg (90.6-lb) sexually intact male Dogue de Bordeaux with urinary incontinence and signs of nausea referred for further evaluation and treatment of bilateral hydronephrosis, hydroureter, and ectopic ureters. A—Sagittal plane ultrasonographic image of the dog's left kidney in a long-axis view showing marked hydronephrosis, with an enlarged renal pelvis (pound sign) and the presence of renal parenchyma (diamonds). The dog's head is toward the left of the image, and the measurement scales across the top and right of the image are in centimeters. B—Reconstructed dorsal plane abdominal CT image after administration of contrast medium. Hydronephrosis (pound signs) and hydroureters (arrows) are evident bilaterally but substantially worse on the right. In addition, the external iliac arteries (asterisks) are evident coursing ventral to and causing compression of the right ureter (RU) and left ureter (LU). The dog's right side and head are toward the left and top of the image, respectively. The image is at the level of the external iliac arteries. LK = Left kidney. RK = Right kidney.

Citation: Journal of the American Veterinary Medical Association 258, 7; 10.2460/javma.258.7.740

Two days later, the dog was returned for abdominal CTc and recheck urinalysis. The patient underwent general anesthesia. Urinalysis performed on a sample collected by cystocentesis revealed results within reference limits, including a urine specific gravity of 1.030. Precontrast abdominal CT images were acquired with a 1.25-mm slice thickness, 120 kV, and 150 mA and reconstructed with the use of a soft tissue algorithm. After IV administration of iodinated contrast medium (iohexold [350 mg iodine/mL solution], 98 mL; 2.4 mL/kg [1.1 mg/lb]), 5 subsequent series of CT images were acquired with the same acquisition parameters. The first postcontrast series was acquired during the late mixed vascular phase of contrast medium dissemination and corresponded with a nephrography phase of contrast medium uptake in the kidneys. Four additional postcontrast series were acquired over the next 13 minutes and displayed various progressive stages of contrast pyelography and excretory phases of contrast medium elimination. By the final series, contrast medium filled the entirety of the left ureter and had begun to pool in the urinary bladder. Two additional reconstruction series were produced from the stored raw imaging data after the dog had been removed from the imaging unit; one series was of the precontrast data reformatted with a bone (sharp) algorithm, and the other was a reformat of the final postcontrast series into 0.625-mm slice thicknesses to improve spatial resolution.

Results of CT indicated a markedly hydronephrotic and enlarged right kidney (19.2 × 16.2 × 11.8 cm), with minimal contrast-enhancing parenchyma along the medial margin and complete loss of all other renal parenchyma of the right kidney (Figure 1). Markedly reduced renal function of the right kidney, compared with the left kidney, was identified with or without right ureteral obstruction because only a small volume of contrast medium was visible in the ventrally dependent portion of the right kidney, and no contrast medium was visible within the right ureter when the final postcontrast series was performed (approx 20 minutes after IV administration of contrast medium). The right ureter had a markedly dilated ureteral lumen (approx 5.1 cm in diameter), was tortuous along its length, and passed dorsal to the external iliac artery (retroiliac ureter). A focal, apparently blind-ended diverticulum (approx 1.8 cm in diameter) was present along the caudal margin of the right ureter at the level of L7. The cryptorchid right testicle was also visible at this level. A small volume of abdominal fluid was found in the immediate vicinity of this diverticulum and the cryptorchid testicle. The caudal terminus of the right ureter extended into the dorsal margin of the prostatic region of the urethra, where the right ureter abruptly terminated without an intramural component. Hydronephrosis of the left kidney was also present and evident by an enlarged renal pelvis (approx 7.0 × 4.0 × 3.9 cm). The diameter of the left ureter varied along its length, measuring 3.9 cm just distal to the renal pelvis, 0.6 cm where the ureter passed dorsal to the external iliac artery (the retroiliac site), and 1.7 cm near its insertion at the trigone. The contrast medium column within the left ureter narrowed and entered the urinary bladder at the level of the trigone but continued caudally for 2.6 cm to the prostatic region of the urethra, representing an intramural component of ureteral ectopia. A small jet of contrast medium in urine was evident at the distal aspect of the trigone of the bladder, approximately 1.4 cm from the distal terminus of the left ureter, and contrast medium in urine pooled cranially within the bladder lumen. Bilaterally, the distal portions of both ureters coursed dorsal to the ipsilateral external iliac arteries (retroiliac ureters). The urethra distal to the level of the prostate appeared normal in size and did not have evidence of contrast medium or fluid accumulation. The medial iliac, hypogastric, and sacral lymph nodes were minimally and symmetrically enlarged, consistent with the dog's young age. Eight lumbar vertebrae were present.

Immediately following CT, the dog underwent exploratory laparotomy. Complete abdominal exploration revealed a markedly enlarged, hydronephrotic right kidney with no palpable renal parenchyma and a moderately enlarged, hydronephrotic left kidney with palpable renal parenchyma. The right renal artery was small, and the right renal vein was not detectable. The caudal vena cava was substantially dilated cranially and closely associated with and compressed by the right kidney. The right ureter was markedly distended but tapered to a smaller diameter at the level of the right external iliac artery, at which point the ureter traversed dorsal to the artery, was compressed in the region of contact with this vessel, and was partially torsed (approx 180°). The serosal surface of the right ureter had a markedly dilated insertion into the serosal surface of the lower urinary tract, extending from the midlevel of the urinary bladder to the prostatic region of the urethra. On exploration, a large intramural component of the ureter was detected, with urinary bladder mucosa present between the ureteral lumen and bladder lumen and ureteral wall outpouching with disruption of the ureteral wall where the serosal surfaces joined and where the ureter coursed over the prostatic region of the urethra. The only communication between the right ureteral lumen and lower urinary tract lumen was a pinpoint opening at the level of the prostatic region of the urethra. The left ureter traversed dorsal to the left external iliac artery and was compressed by this vessel. Proximal to the left external iliac artery, the left ureter was markedly dilated, and distal to this level, the ureter appeared to have a more normal diameter (Figure 2). The left ureter inserted into the urinary bladder distal to the trigone region, and an intramural component was detected extending caudally to its opening in the prostatic region of the urethra. The right testicle was located intra-abdominally, craniodorsal to the urinary bladder, and the associated vas deferens inserted into a right ureteral diverticulum. The right gubernaculum was thick and had an abnormally small associated blood supply. The duodenocolic ligament was absent, and the duodenum coursed directly into the jejunum with no visible duodenal flexure. The mass effect of the severely enlarged right hydronephrotic kidney caused abnormal displacement of the small intestines into the left half of the abdomen. The remainder of the abdominal exploration was unremarkable.

Figure 2
Figure 2

Intraoperative image of the dog described in Figure 1. The distended left ureter (arrows) is visible coursing from the left kidney (LK), dorsal to the left external iliac artery (asterisk), then to the urinary bladder (B). The dog is in dorsal recumbency, with its head toward the top of the image.

Citation: Journal of the American Veterinary Medical Association 258, 7; 10.2460/javma.258.7.740

Given the absence of almost any visible renal parenchyma in the right kidney and the fact that the severe right renomegaly caused displacement of the small intestine, right ureteronephrectomy was performed. The right kidney and proximal ureter were dissected from the retroperitoneal space with a combination of blunt dissection, electrocautery, and the use of a bipolar vessel-sealing device.e The right renal artery (approx 2 mm in diameter) was circumferentially ligated with 2-0 silk suturef and subsequently transected with the bipolar vessel-sealing device distal to the silk ligature. Two hemostatic clamps were placed across the mid-distal portion of the right ureter, just cranial to the level of the external iliac artery; the ureter was transected between these clamps; and the right kidney and proximal portion of the ureter were removed. The distal portion of the right ureter was then clamped with hemostatic clamps caudal to the level of the external iliac artery, and the cranial end of the remaining ureter was passed caudally and dorsally to the right external iliac artery to mobilize the ureter in this region of compression. A stay suture of 3-0 polydioxanoneg was placed at the apex of the urinary bladder, and the distal portion of the right ureter was dissected away with right-angle forceps and monopolar electrocautery. The urinary bladder mucosa and urethral wall were present at the pinpoint site of ureteral insertion in the prostatic region of the urethra, where the ureter was subsequently transected and removed. The urethral lumen was closed with a single bite of 3-0 polydioxanone suture tied in a simple interrupted pattern, and the right ureteral wall surrounding the pinpoint communication was sutured to the urethral wall with 3-0 polydioxanone suture in a simple continuous pattern. The region of the urinary bladder with exposed mucosa was sutured closed (including all bladder wall layers to ensure incorporation of submucosa) with 3-0 polydioxanone suture in a simple interrupted pattern.

Left neoureterocystostomy was then performed. The point of insertion of the left ureter into the urinary bladder caudal to the trigone region was circumferentially ligated with 2-0 polydioxanone suture,g a hemostatic clamp was placed just proximal to the ligature, and the distal portion of the ureter was transected between this clamp and the ligature. The mid-distal region of the left ureter, just cranial to its compression by the left external iliac artery, was clamped with a hemostat and transected to remove approximately 5 cm of its length from the distal end. Cystotomy was performed with a 3-cm incision along the ventral aspect of the bladder, and a small stab incision was made through the left dorsal aspect of the bladder wall near the apex. A stay suture of 3-0 polydioxanone was placed at the cut end of the left ureter, and the ureter was tunneled through the stab incision and into the lumen of the bladder. The cut end of the ureter was then spatulated by making a 1.5-cm full-thickness longitudinal incision proximally. The mucosal layers of the left ureter and bladder wall were apposed with 5-0 polydioxanone sutureg in a simple interrupted pattern; the distal 0.5-cm end of the spatulated ureter was transected and removed before completing these sutures. The serosal surfaces of the bladder and ureter were closed with 4-0 polydioxanone sutureg in a simple interrupted pattern. A 5F red rubber catheter was used to confirm the patency of the new ureteral insertion site into the bladder and to probe the intramural component of the left ectopic ureter that coursed caudally through the bladder wall. This intramural component was closed with a single bite of 3-0 polydioxanone suture that passed through the urethral wall and incorporated urethral mucosa, with the knot tied at the serosal surface. The cystotomy incision was closed with 3-0 polydioxanone suture in a simple interrupted pattern. The urinary bladder was tested for leaks by injecting sterile saline (0.9% NaCl) solution from a 12-mL syringe, through a 25-gauge needle, into the bladder; no leaks were identified.

Right abdominal cryptorchid castration was performed routinely with ligation of the vas deferens, pampiniform plexus, and testicular artery. A right-sided incisional gastropexy was also performed in a standard manner with incisions made in the gastric seromuscular layer and transversus abdominis muscle that were then apposed with 2 lines of 2-0 polydioxanone suture placed in a simple continuous pattern. The abdomen was closed in a routine manner, and a left prescrotal closed castration was subsequently performed routinely. The dog recovered from general anesthesia without complication and was hospitalized postoperatively for monitoring and supportive care, including administration of fluid therapy (isotonic crystalloid solution, 2 mL/kg/h [0.9 mL/lb/h], IV, for the first 24 hours) and analgesics (hydromorphone, 0.05 mg/kg [0.02 mg/lb], IV, q 4 h for the first 24 hours, then buprenorphine, 0.01 mg/kg [0.0045 mg/lb], IV, q 8 h starting on postoperative day 2).

Because the dog had several episodes of regurgitation the day after surgery, gastrointestinal supportive treatment was initiated with metoclopramide (2 mg/kg/d, IV, constant rate infusion), pantoprazole (1 mg/kg [0.45 mg/lb], IV, q 12 h), maropitant (1 mg/kg, IV, q 24 h), and sucralfate slurry (1 g sucralfate in 5 mL water, PO, q 8 h). Focal urinary ultrasonography the day after surgery revealed static to mildly progressive hydronephrosis of the left kidney, persistent left ureteral dilation that tapered distally, left ureteral reimplantation site patency with a visible urine jet, closure of the previous left and right ureteral insertions, mild dilation of the prostatic region of the urethra, and mild free peritoneal gas and abdominal fluid, which were all considered expected findings given the earlier findings and surgical treatment.

Although urinary incontinence was noticed throughout hospitalization, the dog also voided urine in a clinically normal manner. The dog's appetite and regurgitation improved during hospitalization, and findings on serum biochemical analyses performed on postoperative days 1 and 2 included SUN concentrations of 13 and 16 mg/dL, respectively, and creatinine concentrations of 0.7 and 1.0 mg/dL, respectively.

The removed right kidney and ureter, transected portion of the left ureter, and right and left testicles were submitted for histologic examination. Findings for the right kidney indicated severe, chronic hydronephrosis and corticomedullary atrophy with multifocal glomerular cystic atrophy, glomerular obsolescence, tubular dilation and injury, and lymphoplasmacytic, neutrophilic interstitial nephritis. Histologic evaluation of both ureters revealed moderate to severe, chronic urothelial hyperplasia and mural smooth muscle hyperplasia and hypertrophy with rare intravascular mineralization, which was worse in the right ureter than in the left ureter. The gross and histopathologic lesions identified in the submitted urinary tissues were consistent with a long-term obstructive process. The left testicle had histologic evidence of decreased spermatogenesis, and the right testicle had moderate, generalized tubular degeneration and atrophy with interstitial fibrosis and absent spermatogenesis.

Two days after surgery, the dog was discharged with prescriptions of tramadol (3.6 mg/kg [1.6 mg/lb], PO, q 8 to 12 h for 5 to 7 days), maropitant (1.8 mg/kg [0.8 mg/lb], PO, q 24 h as needed for signs of nausea or inappetence), sucralfate slurry (1 g of sucralfate/5 mL of water, PO, q 8 h for 7 days), and omeprazole (1 mg/kg, PO, q 12 h for 10 days). In addition, the owner was instructed to restrict the dog's activities, monitor the dog (overall and the surgical incision site), maintain an E-collar on the dog, and provide incision care.

When the dog was returned for a recheck assessment 11 days after surgery, the owners reported that since hospital discharge, the dog had had a normal appetite and energy level, with activity restriction. Polyuria, polydipsia, and pollakiuria were reported postoperatively; however, no stranguria, hematuria, or dysuria were noticed. In addition, the owners reported that the dog's urinary incontinence had begun to improve several days after surgery. Physical examination revealed vital signs within reference limits; intact and healing laparotomy and castration incision sites with mild crusting and no erythema, swelling, or discharge; and a soft abdomen on palpation with no signs of pain elicited. The dog's urinary bladder was palpable, soft, and approximately 5 cm in diameter. The dog's SUN concentration was 26 mg/dL and creatinine concentration was 1.2 mg/dL. Recheck abdominal ultrasonography revealed persistent but improved left hydronephrosis and left ureteral dilation with a patent left ureter determined on the basis of the presence of obvious ureteral jets. A urine sample was obtained by cystocentesis, and urinalysis revealed a urine specific gravity of 1.017 with 4 to 10 WBCs/hpf and 6 to 8 RBCs/hpf. Aerobic bacterial culture performed on a sample of urine yielded no growth, and a recheck examination in 3 months was recommended.

Six months after surgery, the dog was returned for a recheck assessment. The owners reported that the dog had progressive urinary incontinence when sleeping or recumbent and that the volume of urine during these episodes ranged from several drops to puddles. The owners also reported that the dog had seemingly strong, normal voluntary streams of urine and no signs of hematuria, pollakiuria, stranguria, dysuria, polyuria, or polydipsia. On physical examination, the dog was bright and alert, had a body weight of 48.0 kg (105.6 lb), a body condition score of 5/9, good muscling, and vital signs within reference limits. On abdominal palpation, no signs of pain were elicited, the abdomen was soft, and the urinary bladder was palpable. On point-of-care ultrasonography, the width of the urinary bladder was approximately 20 cm in the transverse plane. The dog was walked outside and urinated a clinically normal stream without stranguria or dysuria. After urination, the dog's urinary bladder was approximately 6 to 7 cm wide as measured with ultrasonography. Other findings on abdominal ultrasonographic examination included static left hydronephrosis, left ureteral dilation (> 2 cm in diameter), and moderate, focal, polypoid mucosal thickening at the neoureterocystostomy site. Cystocentesis was performed, and urinalysis of a portion of the sample revealed a urine specific gravity of 1.030 with rare RBCs and 0 to 3 WBCs/hpf; aerobic bacterial culture performed on a portion of the urine sample yielded no growth. The dog's serum concentrations of urea nitrogen (17 mg/dL) and creatinine (1.1 mg/dL) were within reference limits; however, the serum concentration of SDMAa was mildly high (15 μg/dL, reference range, 0 to 14 μg/dL for adult dogs). Given the dog's pattern of urinary incontinence and that the dog had urine in its bladder after urination with clinically normal voiding behavior, low urethral sphincter closure pressure was suspected as the most likely underlying cause of incontinence, and cystoscopy and positive contrast radiography of the lower urinary tract were recommended for further evaluation.

One month later (7 months after surgery), the dog was returned for a recheck examination. Findings were basically unchanged from the previous examination; therefore, phenylpropanolamine hydrochloride (1.5 mg/kg [0.7 mg/lb], PO, q 12 h) was initiated as a treatment trial for possible urethral sphincter mechanism incompetence as an underlying cause of the dog's persistent urinary incontinence. Reassessments of renal function and blood pressure were recommended to be performed in 3 months.

Follow-up communication with the owner approximately 20 months after surgery revealed that the dog's urinary incontinence persisted despite phenylpropanolamine treatment and was intermittent and generally associated with recumbency. Therefore, estriol (0.04 mg/kg [0.02 mg/lb], PO, q 24 h) was prescribed in addition to ongoing treatment with phenylpropanolamine but yielded no meaningful change in the dog's urinary incontinence. An increase in the frequency of phenylpropanolamine administration from every 12 hours to every 8 hours was recommended, and subsequent placement of a urethral occluder and further diagnostic assessment of the lower urinary tract with cystoscopy and positive contrast radiography were discussed; however, the owner declined. At 24 months after surgical treatment, the dog was reportedly clinically normal, other than persistent urinary incontinence.

Discussion

Multiple congenital urogenital anomalies, including unilateral abdominal cryptorchidism and bilateral retroiliac ectopic ureters with secondary bilateral hydronephrosis and hydroureter, were diagnosed in the dog of the present report. In addition, the dog had urinary incontinence secondary to ureteral ectopia and suspected urethral sphincter mechanism incompetence. Similarly, ureteral ectopia has been reported as the most common congenital cause of urinary incontinence in dogs,1 with possible reasons including ectopic ureteral orifice position and submucosal ureteral tunnel disruption of the smooth muscle layer of the proximal urethral sphincter mechanism.2,3

Ectopic ureters in dogs occur when the metanephric duct (origin of the ureter) arises more cranially on the mesonephric duct (origin of the deferent duct in males, vestigial in females), such that the metanephric duct does not reach the urinary bladder to establish the ureterovesicular junction.2,4 The metanephric duct then continues caudally with the mesonephric duct, with subsequent opening in the neck of the urinary bladder or in the urethra or deferent duct.2 In people and dogs, each ureter typically traverses from the renal pelvis, through the retroperitoneal space ventral to the external iliac vessels, then to the trigone region of the urinary bladder. The embryological anomalies associated with retroiliac ureters are not well understood; however, retroiliac ureters in people have been reported as a cause of distal ureteral obstruction, and 1 theory for this development is a lack of transition from a ventral to a dorsal position of the iliac artery during gestation, with persistence of a ventral root of the umbilical artery.5 A similar scenario may have occurred in the dog of the present report.

Findings in the dog of the present report were consistent with findings of ectopic ureters and ureteral dilation cranial to a vascular ureteral obstruction reported in humans with retroiliac ureters.5,6,7 In addition, the dog had unilateral abdominal cryptorchidism, which emphasized the importance of assessing cryptorchid patients for concurrent congenital urological and genital anomalies. To our knowledge, naturally occurring retroiliac ureters have not been reported previously in dogs. However, we were aware of a study8 of dogs in which ureters were surgically rerouted between the left common iliac vessels, ventral to the inferior mesenteric artery, or through left retroaortic transposition and resulted in experimentally induced hydronephrosis and hydroureter secondary to partial ureteral obstruction from direct mechanical arterial compression and arterial pulsation. The duration between ureteral rerouting and development of hydronephrosis in those dogs was typically 2.5 to 3 months, and histologic evaluation of their ureters revealed inflammatory cell infiltrate and fibrosis.8 Similarly, the dog of the present report had retroiliac ureters with partial ureteral obstruction and secondary bilateral hydroureter and hydronephrosis, which likely arose from the combination of mechanical compression and exposure to arterial pulsation from the external iliac arteries. As evidenced by findings in this dog, naturally occurring retroiliac ureters should be considered as a possible differential diagnosis for urinary obstruction with secondary hydroureter and hydronephrosis in dogs with focal ureteral narrowing. Furthermore, dogs with retroiliac ureters may have additional anatomic anomalies that may require intervention, as did the dog of the present report.

Careful assessment of renal function should be made in any patient for which nephrectomy is considered, and depending on the remaining renal function of both kidneys, surgical treatment options for patients with retroiliac ectopic ureters include repositioning of the ureters to an anatomically normal position, anastomosis to resolve ureteral obstruction, and unilateral ureteronephrectomy. Evaluation of overall renal function may involve assessment of serum creatinine and urea nitrogen concentrations, urine specific gravity, and SDMA concentration. The reported sensitivity and specificity of SDMA concentration for detection of abnormal GFR in dogs are 90% and 87%, respectively.9 However, it is important to also evaluate differential renal function before determining appropriate treatment. Differential GFR can be evaluated with dynamic CT angiography, dynamic renal scintigraphy, or both.10,11,12 Pyelography can provide a qualitative assessment of the kidneys but does not provide a measurement of GFR, especially in patients with ureteral obstruction in which GFR could change dramatically following resolution of the obstruction.13 In the dog of the present report, contrast CT revealed minimal uptake of contrast medium by the right kidney (associated with either a lack of renal function or ureteral obstruction) but greater uptake and subsequent excretion of contrast medium by the left kidney (associated with renal function and urine production). Right ureteronephrectomy was indicated in this dog because of the lack of substantial renal parenchyma detected on ultrasonography and CT, presence of contrast medium in the right renal artery but minimal contrast medium evident in the right renal parenchyma detected on CT, massive hydronephrosis of the right kidney, and suspected mass effect associated with the hydronephrotic right kidney with displacement of abdominal organs and potential contribution to transient abnormal gastrointestinal signs. Concurrent left neoureterocystostomy to treat the left ectopic ureter with repositioning of the ureter in a normal anatomic position was also indicated. Left ureteral reimplantation (end-to-side neoureterocystostomy) was performed, rather than side-to-side neoureterocystostomy or laser ablation, because of the ureteral compression associated with the retroiliac location and the need to transect and reposition the ureter, combined with the intraoperative finding that the left ureter had an intramural component as it coursed caudally and then inserted into the urinary bladder distal to the trigone region. The most proximal point of left ureteral insertion into the lower urinary tract was deemed distal to the typical insertion site of a nonectopic ureter.

At the last follow-up, the owners reported that the dog of the present report was acting normally but had some persistent urinary incontinence. However, the dog likely had some decrease in renal function, given that the last assessments of serum concentrations of SDMA (slightly above the upper reference limit) and creatinine (within reference limits) had increased from earlier concentrations. The dog's persistent urinary incontinence was likely attributable to other concurrent conditions, such as urethral sphincter mechanism incompetence, which could have been associated with disruption of the urethral anatomy. As recommended for the dog of the present report, cystoscopic assessment may be valuable to rule out potential recanalization or dilation of the distal ureteral remnants following surgical treatment of ectopic ureters. In addition, because the dog's persistent, intermittent urinary incontinence did not improve with medical management, hydraulic urethral occluder placement was discussed. Hydraulic occluder placement in male dogs with urinary incontinence has been described with good long-term outcomes and improved urinary continence scores.14,15 The owners declined cystoscopic assessment and hydraulic urethral occluder placement.

Imaging modalities, such as ultrasonography and CT, are valuable in assessing urogenital anomalies, determining prognoses, guiding treatment decisions, and planning surgery.16,17 In the dog of the present report, abdominal ultrasonography was valuable in identifying ureteral anomalies (eg, hydroureter, ectopia, and partial obstruction) but did not provide accurate anatomic information regarding the specific vessels involved with the obstruction. Findings on ultrasonography were consistent with suspected retrocaval (also called circumcaval ureters), which have been reported frequently in cats but rarely in dogs.18,19,20 However, the findings on CT were more consistent with the intraoperative findings of retroiliac ureters. In addition, CT aided in surgical planning by allowing for further assessment of possible renal function because we observed a lack of contrast medium uptake in the right kidney and ureter, compared with uptake, excretion, and passage of contrast medium by the left kidney, through the left ureter, and into the urinary bladder. These findings further highlighted the importance of advanced imaging techniques in assessing and treating the dog of the present report and indicated that such could be valuable to veterinarians caring for similarly affected dogs in the future.

To our knowledge, this was the first report of a dog with retroiliac ureters and compression-induced ureteral obstruction with secondary hydroureter and hydronephrosis. Retroiliac ureters, alone or in combination with other abnormalities, should be included as a differential diagnosis in young dogs with ureteral obstruction. Findings in the dog of the present report underscored the value of multiple imaging modalities when evaluating dogs with urogenital abnormalities and indicated that a good outcome was possible for a dog with retroiliac ureters treated surgically. Additional research on retroiliac ureters in dogs is warranted.

Acknowledgments

No external funding was used in conjunction with this report, and the authors declare that there were no conflicts of interest.

The authors thank Dr. Derek Cissell for assistance with interpretation of the CT and ultrasonographic images.

Footnotes

a.

Idexx Laboratories Inc, Westbrook, Me.

b.

Aplio i700, Canon Medical Systems USA Inc, Tustin, Calif.

c.

LightSpeed-16, GE Healthcare, Chicago, Ill.

d.

Omnipaque 350 mg iodine/mL, GE Healthcare, Chicago, Ill.

e.

LigaSure Impact, Medtronic, Minneapolis, Minn.

f.

Ethicon Inc, Somerville, NJ.

g.

PDS suture, Ethicon Inc, Somerville, NJ.

Abbreviations

GFR

Glomerular filtration rate

SDMA

Symmetric dimethylarginine

References

  • 1.

    Holt Pe, Moore AH. Canine ureteral ectopia: an analysis of 175 cases and comparison of surgical treatments. Vet Rec 1995;136:345349.

  • 2.

    Sutherland-Smith J, Jerram RM, Walker AM, et al. Ectopic ureters and ureteroceles in dogs: presentation, cause, and diagnosis. Compend Contin Educ Pract Vet 2004;26:303310.

    • Search Google Scholar
    • Export Citation
  • 3.

    McLoughlin MA, Chew DJ. Diagnosis and surgical management of ectopic ureters. Clin Tech Small Anim Pract 2000;15:1724.

  • 4.

    Owen RR. Canine ureteral ectopia—a review. 1. Embryology and aetiology. J Small Anim Pract 1973;14:407417.

  • 5.

    Gupta NP, Gill IS, Bhatia V. Retroiliac ureter with contralateral transverse malrotation of kidney: treated by crossed ureterocaliceal anastomosis. J Urol 1987;138:118119.

    • Search Google Scholar
    • Export Citation
  • 6.

    Nguyen DH, Koleilat N, Gonzalez R. Retroiliac ureter in a male newborn with multiple genitourinary anomalies: case report and review of the literature. J Urol 1989;141:14001403.

    • Search Google Scholar
    • Export Citation
  • 7.

    Hanna MK. Bilateral retroiliac-artery ureters. Br J Urol 1972;44:339344.

  • 8.

    Cockett AT, Nakamura RM, Rein BI. The role of arterial pulsation in experimental hydronephrosis. Invest Urol 1965;2:548554.

  • 9.

    Pelander L, Häggström J, Larsson A, et al. Comparison of the diagnostic value of symmetric dimethylarginine, cystatin C, and creatinine for detection of decreased glomerular filtration rate in dogs. J Vet Intern Med 2019;33:630639.

    • Search Google Scholar
    • Export Citation
  • 10.

    Chang J, Kim S, Jung J, et al. Evaluation of the effects of thiopental, propofol, and etomidate on glomerular filtration rate measured by the use of dynamic computed tomography in dogs. Am J Vet Res 2011;72:146151.

    • Search Google Scholar
    • Export Citation
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    O'Dell-Anderson KJ, Twardock R, Grimm JB, et al. Determination of glomerular filtration rate in dogs using contrast-enhanced computed tomography. Vet Radiol Ultrasound 2006;47:127135.

    • Search Google Scholar
    • Export Citation
  • 12.

    Daniel GB, Mitchell SK, Mawby D, et al. Renal nuclear medicine: a review. Vet Radiol Ultrasound 1999;40:572587.

  • 13.

    Feeney DA, Johnston GR. The kidney and ureters. In: Thrall DE, ed. Textbook of veterinary diagnostic radiology. 5th ed. St Louis: Saunders Elsevier, 2007;693707.

    • Search Google Scholar
    • Export Citation
  • 14.

    Morgan K, Milner HR, Tikekar A, et al. Long-term use of hydraulic artificial urethral sphincters in nine dogs from New Zealand with urethral sphincter mechanism incompetence. N Z Vet J 2018;66:205209.

    • Search Google Scholar
    • Export Citation
  • 15.

    Reeves L, Adin C, McLoughlin M, et al. Outcome after placement of an artificial urethral sphincter in 27 dogs. Vet Surg 2013;42:1218.

  • 16.

    Lamb CR, Gregory SP. Ultrasonographic findings in 14 dogs with ectopic ureter. Vet Radiol Ultrasound 1998;39:218223.

  • 17.

    Samii VF, McLoughlin MA, Mattoon JS, et al. Digital fluoroscopic excretory urography, digital fluoroscopic urethrography, helical computed tomography, and cystoscopy in 24 dogs with suspected ureteral ectopia. J Vet Intern Med 2004;18:271281.

    • Search Google Scholar
    • Export Citation
  • 18.

    Bélanger R, Shmon CL, Gilbert PJ, et al. Prevalence of circumcaval ureters and double caudal vena cava in cats. Am J Vet Res 2014;75:9195.

  • 19.

    Steinhaus J, Berent AC, Weisse C, et al. Clinical presentation and outcome of cats with circumcaval ureters associated with a ureteral obstruction. J Vet Intern Med 2015;29:6370.

    • Search Google Scholar
    • Export Citation
  • 20.

    Doust RT, Clarke SP, Hammond G, et al. Circumcaval ureter associated with an intrahepatic portosystemic shunt in a dog. J Am Vet Med Assoc 2006;228:389391.

    • Search Google Scholar
    • Export Citation
  • Figure 1

    Ultrasonographic (A) and postcontrast CT (B) images of an 8-month-old 41.2-kg (90.6-lb) sexually intact male Dogue de Bordeaux with urinary incontinence and signs of nausea referred for further evaluation and treatment of bilateral hydronephrosis, hydroureter, and ectopic ureters. A—Sagittal plane ultrasonographic image of the dog's left kidney in a long-axis view showing marked hydronephrosis, with an enlarged renal pelvis (pound sign) and the presence of renal parenchyma (diamonds). The dog's head is toward the left of the image, and the measurement scales across the top and right of the image are in centimeters. B—Reconstructed dorsal plane abdominal CT image after administration of contrast medium. Hydronephrosis (pound signs) and hydroureters (arrows) are evident bilaterally but substantially worse on the right. In addition, the external iliac arteries (asterisks) are evident coursing ventral to and causing compression of the right ureter (RU) and left ureter (LU). The dog's right side and head are toward the left and top of the image, respectively. The image is at the level of the external iliac arteries. LK = Left kidney. RK = Right kidney.

  • Figure 2

    Intraoperative image of the dog described in Figure 1. The distended left ureter (arrows) is visible coursing from the left kidney (LK), dorsal to the left external iliac artery (asterisk), then to the urinary bladder (B). The dog is in dorsal recumbency, with its head toward the top of the image.

  • 1.

    Holt Pe, Moore AH. Canine ureteral ectopia: an analysis of 175 cases and comparison of surgical treatments. Vet Rec 1995;136:345349.

  • 2.

    Sutherland-Smith J, Jerram RM, Walker AM, et al. Ectopic ureters and ureteroceles in dogs: presentation, cause, and diagnosis. Compend Contin Educ Pract Vet 2004;26:303310.

    • Search Google Scholar
    • Export Citation
  • 3.

    McLoughlin MA, Chew DJ. Diagnosis and surgical management of ectopic ureters. Clin Tech Small Anim Pract 2000;15:1724.

  • 4.

    Owen RR. Canine ureteral ectopia—a review. 1. Embryology and aetiology. J Small Anim Pract 1973;14:407417.

  • 5.

    Gupta NP, Gill IS, Bhatia V. Retroiliac ureter with contralateral transverse malrotation of kidney: treated by crossed ureterocaliceal anastomosis. J Urol 1987;138:118119.

    • Search Google Scholar
    • Export Citation
  • 6.

    Nguyen DH, Koleilat N, Gonzalez R. Retroiliac ureter in a male newborn with multiple genitourinary anomalies: case report and review of the literature. J Urol 1989;141:14001403.

    • Search Google Scholar
    • Export Citation
  • 7.

    Hanna MK. Bilateral retroiliac-artery ureters. Br J Urol 1972;44:339344.

  • 8.

    Cockett AT, Nakamura RM, Rein BI. The role of arterial pulsation in experimental hydronephrosis. Invest Urol 1965;2:548554.

  • 9.

    Pelander L, Häggström J, Larsson A, et al. Comparison of the diagnostic value of symmetric dimethylarginine, cystatin C, and creatinine for detection of decreased glomerular filtration rate in dogs. J Vet Intern Med 2019;33:630639.

    • Search Google Scholar
    • Export Citation
  • 10.

    Chang J, Kim S, Jung J, et al. Evaluation of the effects of thiopental, propofol, and etomidate on glomerular filtration rate measured by the use of dynamic computed tomography in dogs. Am J Vet Res 2011;72:146151.

    • Search Google Scholar
    • Export Citation
  • 11.

    O'Dell-Anderson KJ, Twardock R, Grimm JB, et al. Determination of glomerular filtration rate in dogs using contrast-enhanced computed tomography. Vet Radiol Ultrasound 2006;47:127135.

    • Search Google Scholar
    • Export Citation
  • 12.

    Daniel GB, Mitchell SK, Mawby D, et al. Renal nuclear medicine: a review. Vet Radiol Ultrasound 1999;40:572587.

  • 13.

    Feeney DA, Johnston GR. The kidney and ureters. In: Thrall DE, ed. Textbook of veterinary diagnostic radiology. 5th ed. St Louis: Saunders Elsevier, 2007;693707.

    • Search Google Scholar
    • Export Citation
  • 14.

    Morgan K, Milner HR, Tikekar A, et al. Long-term use of hydraulic artificial urethral sphincters in nine dogs from New Zealand with urethral sphincter mechanism incompetence. N Z Vet J 2018;66:205209.

    • Search Google Scholar
    • Export Citation
  • 15.

    Reeves L, Adin C, McLoughlin M, et al. Outcome after placement of an artificial urethral sphincter in 27 dogs. Vet Surg 2013;42:1218.

  • 16.

    Lamb CR, Gregory SP. Ultrasonographic findings in 14 dogs with ectopic ureter. Vet Radiol Ultrasound 1998;39:218223.

  • 17.

    Samii VF, McLoughlin MA, Mattoon JS, et al. Digital fluoroscopic excretory urography, digital fluoroscopic urethrography, helical computed tomography, and cystoscopy in 24 dogs with suspected ureteral ectopia. J Vet Intern Med 2004;18:271281.

    • Search Google Scholar
    • Export Citation
  • 18.

    Bélanger R, Shmon CL, Gilbert PJ, et al. Prevalence of circumcaval ureters and double caudal vena cava in cats. Am J Vet Res 2014;75:9195.

  • 19.

    Steinhaus J, Berent AC, Weisse C, et al. Clinical presentation and outcome of cats with circumcaval ureters associated with a ureteral obstruction. J Vet Intern Med 2015;29:6370.

    • Search Google Scholar
    • Export Citation
  • 20.

    Doust RT, Clarke SP, Hammond G, et al. Circumcaval ureter associated with an intrahepatic portosystemic shunt in a dog. J Am Vet Med Assoc 2006;228:389391.

    • Search Google Scholar
    • Export Citation

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