Ch313 - Congenital Lower Urinary Tract Disorders Flashcards
What is an ectopic ureter?
A congenital abnormality in which at least 1 ureteral opening is located distal (caudal) to the bladder trigone.
What are the two main types of ectopic ureters?
- Intramural (86-100% of cases in dogs) - tunnels submucosally through bladder/urethra wall
- Extramural - bypasses bladder and inserts directly into urethra, vagina, or uterus
Which breeds are predisposed to ectopic ureters?
Golden Retriever, Labrador Retriever, Newfoundland, Siberian Husky, Poodle, Soft Coated Wheaten Terrier, and Entlebucher Mountain Dog (confirmed hereditary)
What is the primary clinical sign of ectopic ureters?
Urinary incontinence, though some animals may show no clinical signs due to high urethral tone and retrograde flow of urine into the bladder
What is the preferred diagnostic method for ectopic ureters in female dogs vs male dogs/cats?
- Female dogs: Cystoscopy (100% sensitivity)
- Male dogs and cats: Computed tomographic excretory urography (CTEU)
What is a ureterocele?
A cystic dilatation of the submucosal portion of the distal ureter
What are the two types of ureteroceles?
- Orthotopic - ureterocele and ureteric opening located within bladder
- Ectopic - any portion of ureterocele located within urethra
What are the three types of urachal anomalies?
- Patent urachus - open communication between bladder and umbilicus
- Urachal cyst - isolated section with epithelial secretory lining
- Vesicourachal diverticulum - persistent communication of proximal urachus with bladder apex
What is bladder hypoplasia most commonly associated with?
It’s most commonly secondary to other conditions causing urinary incontinence in juvenile animals, such as ectopic ureters or congenital urethral sphincter mechanism incompetence
What is hypospadias?
A failure of fusion of the urogenital folds resulting in incomplete formation of the ventral aspect of the urethra
What is the difference between hypospadias and epispadias?
- Hypospadias: Incomplete formation of ventral urethra
- Epispadias: Incomplete formation of dorsal urethra
What are the main signs associated with urethrorectal/rectovaginal fistulae?
- Feces or urine exiting from incorrect orifice
- Possible perineal bulging if fecal material cannot pass
- Common urinary tract infections
- Hematuria, stranguria, and pollakiuria may occur
What are the three main vestibulovaginal junction anomalies?
- Vestibulovaginal stenosis
- Vestibulovaginal septal remnant (VVSR)
- Dual vagina
What is a vestibulovaginal septal remnant (VVSR)?
A vertical band of tissue resulting from retention of epithelium at the point of mesonephric duct fusion, ranging from thin lesions to thick bands extending into the vagina
What percentage of dogs with ectopic ureters also have vestibulovaginal septal remnants?
93% of dogs with ectopic ureters have concurrent VVSRs
What percentage of female dogs experience persistent urinary incontinence after ectopic ureter treatment?
35-63% of female dogs experience persistent incontinence after treatment
What is the success rate of treating ectopic ureters in male dogs?
Much better than females - 100% continence reported with laser ablation in one study of 4 dogs, and 82% continence rate reported in 16 male dogs treated with conventional surgery
What concurrent congenital abnormalities are commonly seen with ectopic ureters?
- Renal dysplasia/hypoplasia/aplasia
- Ureterocele
- Urethral hypoplasia
- Vestibulovaginal abnormalities
What secondary complications can develop with ectopic ureters?
- Hydronephrosis
- Hydroureter
- Bladder hypoplasia
- Recurrent urinary tract infections
What is the typical age of presentation for ectopic ureters?
- Dogs: Often <6 months of age, though males may present when older
- Cats: Mean age of 1.4 years
- Should remain on differential list lifelong for compatible clinical signs
What percentage of dogs with ectopic ureters have urinary tract infections? and what is the most common bacteria?
Up to 83% of female dogs and 36% of cats, most commonly due to E. coli
What is the sensitivity of ultrasound for diagnosing ectopic ureters?
95% in a recent study, but significantly lower sensitivities have been reported due to operator dependence
What are the treatment options for intramural ectopic ureters?
- Preferred: Transurethral cystoscopic-guided laser ablation
- Alternative: Cystoscopic-guided scissor transection
- Surgical correction (intravesicular neoureterostomy or extravesicular ureteral re-implantation)
What are the clinical signs of ureteroceles?
- May be asymptomatic
- Lower urinary tract signs (stranguria, pollakiuria, urinary incontinence)
- Abdominal pain if upper urinary tract obstruction or infection present
What is the preferred treatment for ureteroceles?
Endoscopic-guided laser ablation is the treatment of choice due to safety and low morbidity
What is the frequency of vesicourachal diverticulae in a study of 28,714 ultrasounds:
- Vesicourachal diverticulae: 96.7% in cats, 89.5% in dogs
What is the frequency of urachal anomalies in a study of 28,714 ultrasounds:
- Overall prevalence: 0.93% in cats, 0.18% in dogs
What complications can arise from a patent urachus?
- Urine leakage
- Urine scald dermatitis
- Omphalitis
- Ascending UTI
- Rarely, uroabdomen
What are the key features of trigonal diverticulae?
- Result from abnormal detrusor muscle development
- Lead to herniation of bladder mucosa
- Predispose to infection and struvite calculi
- Can cause urinary outflow obstruction or vesicoureteral reflux
- Surgical diverticulectomy needed if symptomatic or >5cm diameter
What is congenital urethral sphincter mechanism incompetence (USMI)?
A functional abnormality where urethral muscular tone is insufficient to retain urine in the bladder, particularly during recumbency
What treatment options exist for congenital USMI?
- May self-resolve after first estrus
- Medical management with alpha-1 adrenergic agonists
- Urethral lengthening procedures for severe urethral hypoplasia
What are the characteristics of urethral duplication and what are the treatment options?
- Rare congenital abnormality
- Presents with urinary incontinence
- Treatment options:
- Surgical ligation of accessory urethra
- Minimally invasive ablation using coil embolization and cyanoacrylate glue
What percentage of female dogs with vestibulovaginal septal remnants have concurrent abnormalities?
89% of dogs with VVSR have concurrent abnormalities
How can vestibulovaginal septal remnants be treated?
- Endoscopic laser ablation (preferred)
- Endoscopic scissors
- Surgical resection (more invasive, requires episiotomy)
What is the vestibulovaginal ratio and what is it used to diagnose?
- Ratio of height of vestibulovaginal junction to height of vagina
- <0.33 commonly quoted for stenosis
- <0.20 more significant as clinical signs better correlate to severe stenosis
What factors have been investigated but show no association with treatment outcome in ectopic ureters?
- Breed
- Uni- vs bilateral disease
- Classification of EU
- Age at presentation
- Position of bladder/length of urethra
- Concurrent UTI
When should artificial urethral sphincter placement be considered for ectopic ureters?
Only after:
- Initial treatment (e.g., laser ablation)
- Persistent incontinence despite medical management
- At least one estrous cycle has occurred
What is the success rate of artificial urethral sphincter placement in dogs with persistent incontinence after EU treatment?
80% effective in one study