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Urethral Obstruction 1009

• Subcutaneous ureteral bypass (SUB) device Possible Complications • Bilateral ureteral obstruction is rare
(p. 1174) • Renal failure (acute or chronic) compared to unilateral obstruction but is
VetBooks.ir ○ A newer treatment modality that may • Urinary rupture and uroabdomen • Ureteral obstruction can recur, especially in Diseases and Disorders
• Postoperative ureteral stenosis
○ Indicated for ureteral stenosis or uretero-
life-threatening.
lithiasis, primarily in cats and small dogs
the presence of existing nephroliths.
Recommended Monitoring
replace other treatment options but is
not without complications • Repeat ultrasound at 2 weeks after initial Prevention
• Ureteral stent placed via interventional evaluation and treatment, then monthly Strategies that limit the formation of urolithiasis
endoscopy or surgery until resolved or stable. Remaining renal (pp. 1014, 1016, and 1019)
○ Limited availability; surgery is more widely parenchymal changes are likely permanent.
available, which is important if the patient • Animals with permanent hydroureter/ Technician Tips
is unstable. hydronephrosis are monitored as for chronic Animals in acute renal failure should have
○ Primarily indicated for middle-sized to kidney disease (pp. 23 and 169). Azotemic urine output carefully quantified. One possible
large dogs animals are monitored more intensively than correctible cause of oliguria/anuria is bilateral
• Ureteral surgery nonazotemic animals. ureteral obstruction.
○ Major complication is postoperative
ureteral stricture formation. PROGNOSIS & OUTCOME Client Education
○ Ureterotomy for intraluminal or intramu- Strict adherence to dietary recommendations
ral obstruction in the proximal third of • Depends on underlying cause, duration of can minimize the risk of ureteral or urethral
the ureter obstruction, extent of renal parenchymal obstruction due to urolithiasis.
○ Ureteroneocystostomy for resection of damage, presence of concurrent infection,
distal ureter and ability to resolve underlying cause SUGGESTED READING
○ Ureteroureterostomy to repair ureter after • Structural renal changes persisting 14-45 days Berent A, et al: Subcutaneous ureteral bypass device
resection or transection (anastomosis of or more after relief of ureteral obstruction placement for benign ureteral obstruction in cats:
proximal ureter to distal portion of ureter are generally permanent. 137 cats (174 ureters). J Vet Intern Med 30:1539-
on ipsilateral side), usually when proxi- • Complete bilateral obstruction of more than 1540, 2016.
mal third cannot be implanted directly 3 days is fatal without appropriate treatment. AUTHOR: Adam Mordecai, DVM, MS, DACVIM
into bladder neck; highest incidence of EDITOR: Leah A. Cohn, DVM, PhD, DACVIM
postoperative obstruction PEARLS & CONSIDERATIONS
• Nephrectomy is reserved for animals with
unilateral obstruction, adequate function in Comments
contralateral kidney, and loss of virtually all • Ureteral obstruction should be considered
function in the affected kidney. in the differential diagnosis for renal failure,
especially in patients with evidence of
Nutrition/Diet nephrolithiasis or pyelonephritis.
Diet appropriate for preventing specific urolith
type

Urethral Obstruction Client Education
Sheet

BASIC INFORMATION • Neoplasia PHYSICAL EXAM FINDINGS
• Urinary tract infection • Enlarged, turgid urinary bladder (characteristic)
Definition • Risk factors associated with urolithiasis (pp. • Abdominal discomfort (common)
The common condition involves obstruction 1014, 1016, and 1019) • Dribbling urine (occasionally)
of the lower urinary tract and is usually due to • Bloody preputial/vulvar discharge (occasion-
urolith or matrix formation. Other causes (e.g., ASSOCIATED DISORDERS ally)
neoplasia, stricture, infections) are less common. • Hydronephrosis • Palpable urethral urolith or tumor (digital
• Azotemia/uremia rectal exam in dogs) (occasionally)
Epidemiology • Hyperkalemic cardiac dysrhythmia • Bradycardia if severe hyperkalemia (in very
SPECIES, AGE, SEX • Urinary bladder rupture advanced cases)
• Cats and less commonly dogs of any age • Bladder atonia/hypotonia
• Males are anatomically predisposed to • Urinary tract infection Etiology and Pathophysiology
obstruction. • Postobstructive diuresis • Urine supersaturation, urinary tract infection,
certain disease states, and breed predisposi-
GENETICS, BREED PREDISPOSITION Clinical Presentation tion contribute to urolithiasis.
• Certain breeds predisposed to specific urolith HISTORY, CHIEF COMPLAINT • In cats especially, urethral plugs may be
formation (e.g., Dalmatians: urate uroliths) • Urinary tract signs: pollakiuria, dysuria, composed of matrix (cellular debris, virus-like
• Other breeds predisposed to urethral neo- stranguria, anuria/oliguria, hematuria, drib- particles, ± bacteria, urinary crystals).
plasia (e.g., Scottish terrier) bling urine, licking prepuce/vulva (urethral • Uroliths or plugs can obstruct the urethra;
discharge) urethral anatomy favors obstruction in males.
RISK FACTORS • Systemic signs: lethargy, anorexia, vocaliza- • Neoplasia, especially transitional cell carcinoma
• Feline lower urinary tract signs/disease tion, restlessness, weakness, discomfort (p. 991), may progress to cause obstruction.
(FLUTS/D) (p. 332) • History of urinary infection or urolithiasis • Urethritis may lead to urethral stricture.

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