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Jenelle M. Soppet VCA Animal Specialty & Emergency Center, 1535 S Sepulveda Blvd, Los Angeles, CA 90025.

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David Szabo VCA Animal Specialty & Emergency Center, 1535 S Sepulveda Blvd, Los Angeles, CA 90025.

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History

A 2-year-old 19.4-kg (42.7-lb) sexually intact female Australian Shepherd was referred for further consultation regarding a 1-month history of stranguria and pollakiuria. Voluntary urination was apparently nonpainful and no pigmenturia was present. The patient had been adopted from a rescue organization 1 year earlier and did not have signs of lower urinary tract disease until the current episode. The dog was otherwise healthy with normal appetite and energy levels.

On physical examination, the patient was bright, alert, and responsive. The dog's body temperature, heart rate, and respiratory rate were within reference limits. The dog had mildly erythematous pinnae and mild generalized periodontal disease. Findings on the remainder of the physical examination were unremarkable.

Results of a CBC, serum biochemical analysis, and urinalysis were within reference range limits. A urine sample was submitted for bacteriologic culture and antimicrobial susceptibility testing. No microbial growth was noted after 72 hours of culture.

Survey abdominal radiography and excretory urography were performed by the referring veterinarian. Findings on survey abdominal radiographs were unremarkable. For excretory urography, contrast mediuma (2 mL/kg [0.9 mg/lb]; 40 mL total) was administered IV. Excretory urographic images were taken 5 minutes (right lateral view) and 20 minutes (ventrodorsal view) following IV administration of contrast medium (Figure 1).

Figure 1—
Figure 1—

Right lateral (A) and ventrodorsal (B) excretory urographie views of the abdomen of a 2-year-old 19.4-kg (42.7-lb) sexually intact female Australian Shepherd with a 1-month history of stranguria and pollakiuria. Images were taken 5 minutes (right lateral) and 20 minutes (ventrodorsal) following IV administration of contrast medium.a

Citation: Journal of the American Veterinary Medical Association 253, 9; 10.2460/javma.253.9.1113

Determine whether additional imaging studies are required, or make your diagnosis from Figure 1—then turn the page →

Diagnostic Imaging Findings and Interpretation

The urinary bladder contains an increasing amount of contrast medium. A smoothly marginated, radiolucent, thin-walled, and contrast-filled structure is seen in the trigone region of the urinary bladder extending into the lumen. There is dilation of the right renal pelvis and calyces, consistent with hydronephrosis; however, this finding was not present on excretory urographs taken later (not presented). The right ureter is severely dilated with contrast medium and mildly tortuous (Figure 2). In both images, the right ureter appears to insert into the urinary bladder in the correct location with no evidence of ectopia. Excretory urographic findings were consistent with a diagnosis of orthotopic right ureterocele with right hydroureter and transient hydronephrosis.

Figure 2—
Figure 2—

Same excretory urographic images as in Figure 1. Notice the smoothly marginated, radiolucent, thin-walled, and contrast-filled ureterocele (asterisk) in the trigone region of the contrast-filled urinary bladder (UB). On both images, the right ureter is severely enlarged and mildly tortuous in appearance (arrow) but appears to insert into the urinary bladder in the correct location with no evidence of ectopia.

Citation: Journal of the American Veterinary Medical Association 253, 9; 10.2460/javma.253.9.1113

Abdominal ultrasonography, which was performed for academic purposes and to better evaluate the kidneys, revealed a fluid-dilated right ureter with thickened walls. The dilated right ureter was continuous with a round, fluid-filled structure within the trigone region of the urinary bladder (Figure 3). The left ureter appeared normal. Pyelectasia and hydronephrosis were not observed in either kidney.

Figure 3—
Figure 3—

Sagittal ultrasonographic image of the urinary bladder and right ureter of the dog in Figure 1. The dog is in dorsal recumbency. Notice the fluid-dilated right ureter with thickened walls (RU); this ureter inserts into the urinary bladder in a normal anatomic location and is continuous with a round, fluid-filled ureterocele (asterisk) within the trigone region of the urinary bladder (UB). The image was obtained transabdominally with a 2- to 11-MHz microconvex transducer.

Citation: Journal of the American Veterinary Medical Association 253, 9; 10.2460/javma.253.9.1113

Treatment and Outcome

Orthotopic ureterocele was confirmed on exploratory laparotomy. An approximately 4-cm-diameter, fluid-filled structure was palpated within the urinary bladder lumen in the region of the trigone. The right ureter was dilated and fluid filled, but both ureters appeared to enter the urinary bladder in a normal anatomic location. After a cystotomy was performed, the ureterocele was incised and the right ureteral opening was identified at the proximal aspect of the ureterocele. The free wall of the ureterocele was excised, and the cut margins were sutured to the urinary bladder mucosa. The patient recovered without complication and was reportedly continent without signs of lower urinary tract disease 2 weeks after surgery.

Comments

Ureteroceles are an anomalous congenital dilation of the submucosal layer in the distal aspect of the ureters. They are considered uncommon in dogs and are more commonly identified in female dogs than male dogs.1

Both anatomic and functional classification systems of ureteroceles have been proposed. Two anatomic variations of ureteroceles are described in the literature: orthotopic and ectopic.2 Orthotopic ureteroceles are contained entirely within the urinary bladder and have an opening in the region of the ureteral orifice.2 Ectopic ureteroceles have an abnormal anatomic location and may originate from the urinary bladder neck or urethra in association with an ectopic ureter.2 The ureterocele was orthotopic in the case described in the present report, although ureteroceles are more commonly ectopic.1

Ureteroceles have been associated with renal insufficiency most likely secondary to chronic pyelonephritis or ureteral or urethral obstruction.3 A functional classification system has been adapted from the human medical literature that aims to prognosticate outcome through a grading scheme defined by the presence of unilateral or bilateral ureteral and renal involvement.3 The dog of the present report would be classified as having a grade 2/3 ureterocele because of the ipsilateral hydroureter and transient ipsilateral hydronephrosis; most dogs with grade 2 ureteroceles are clinically normal following surgical correction of the ureterocele.3

A complete clinicopathologic evaluation that included a CBC, serum biochemical analysis, urinalysis, and bacteriologic urine culture was performed in the dog of the present report to rule out renal insufficiency. The location of the ureterocele likely caused inflammation or transient urethral obstruction resulting in the stranguria and pollakiuria. The cause of the transient, mild hydronephrosis in the patient of the present report was unknown but may have been related to a brief increase in urinary hydrostatic pressure as a result of the excretory urography or contrast medium–induced diuresis. If persistent, urethral or ureteral obstruction can progress to hydronephrosis, which can lead to pressure-induced renal atrophy and irreversible renal dysfunction. Bacteriologic urine culture results were negative for the dog of the present report; however, if left untreated, this patient could have developed pyelonephritis because hydroureter may predispose to ascending urinary tract infections.4

Traditionally, a diagnosis of ureterocele has been made by use of contrast radiography. On excretory urography, orthotopic ureteroceles may appear as a contrast-enhancing mass (ie, cobra-head sign) in the trigone region of the urinary bladder as contrast medium often collects within the ureterocele before ultimately traveling into the urinary bladder through a connection between the ureterocele and urinary bladder.5 Alternatively, an orthotopic ureterocele may appear as a spherical negative filling defect within the urinary bladder on positive-contrast cystography.5 In the case described in the present report, the ureterocele appeared on excretory urography as a contrast-filled structure with a radiolucent wall in an otherwise contrast-filled urinary bladder. Contrast filling of the ureterocele indicated the presence of glomerular filtration, although the appropriateness of renal function cannot be estimated from imaging findings. Instead, renal function in the dog of the present report was evaluated and determined to be appropriate owing to serum biochemical analysis and urinalysis results within reference limits. Ultrasonography can also be useful for diagnosis of ureterocele. Ureteroceles most commonly appear as thin-walled, anechoic, fluid-filled structures within the trigone region of the urinary bladder (ie, cyst within a cyst) on ultrasonography.6

Acknowledgments

The authors thank Dr. Ronald Koss for help in the management of the case described in this report.

Footnotes

a.

Hypaque, Amersham Health Inc, Princeton, NJ.

References

  • 1. Tattersall JA, Welsh E. Ectopic ureterocele in a male dog: a case report and review of surgical management. J Am Anim Hosp Assoc 2006;42:395400.

  • 2. Kroovand RL. Ureterocele. Urol Clin North Am 1983;10:445449.

  • 3. Stiffler KS, McCrackin Stevenson MA, Mahaffey MB, et al. Intravesical ureterocele with concurrent renal dysfunction in a dog: a case report and proposed classification system. J Am Anim Hosp Assoc 2002;38:3339.

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  • 4. Klahr S. Pathophysiology of obstructive nephropathy. Kidney Int 1983;23:414426.

  • 5. McLoughlin MA, Hauptman JG, Spaulding K. Canine ureteroceles: a case report and literature review. J Am Anim Hosp Assoc 1989;25:699706.

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  • 6. Takiguchi M, Yasuda J, Ochiai K, et al. Ultrasonographic appearance of orthotopic ureterocele in a dog. Vet Radiol Ultrasound 1997;38:398399.

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