ISSN 2398-2969      

Urinary obstruction



  • Cause: urolithiasis, mass, prostatic disease, pyelonephritis, proliferative urethritis, iatrogenic ligation of ureters during spay, stricture, dyssynergia.
  • Signs: dysuria, stranguria, hematuria, lethargy, anorexia, signs of renal disease, abdominal pain.
  • Diagnosis: signs, urinalysis, imaging.
  • Treatment: catheterize, balloon dilation, stenting or surgically remove urethral obstructions; medical treatment, ureteral stents, subcutaneous ureteral bypass devices or surgery for ureteral obstruction.
  • Prognosis: dependent on underlying cause:
    • Neoplasia (grave).
    • Urolithiasis, urethritis, dyssynergia, prostatic disease (good if treatment initiated promptly).



Predisposing factors


  • Male dogs more frequently obstruct secondary to urolithiasis.
  • Struvite urolithiasis and proliferative urethritis most commonly associated with infection.
  • Urethral neoplasia is more common in female dogs.
  • Specific breed disposition, eg Dalmatian/urate, for urolithiasis.
  • Reflex dyssynergia most commonly occurs in large and giant-breed male dogs. 


  • Urethral obstruction Urethra: obstruction commonly occurs in dogs as a result of urolithiasis, neoplasia or trauma.
  • Acute urethral obstruction is seen most commonly in male dogs due to obstruction by calculi lodged at the base of the os penis.
  • Prolonged ureteric obstruction Ureter: urolithiasis (>7 days in experimental studies) → dilation of proximal segment and hydronephrosis Hydronephrosis / hydroureter , eg correction of obstruction at 4 weeks: renal function 25% of normal.
  • If obstruction is relieved within 7 days - little permanent damage in experimental studies.
  • Complete urethral obstruction can result in hydroureter, hydronephrosis, and bladder rupture → azotemia, hyperkalemia, acidosis.


  • Days.
  • Correction of ureter obstruction within 7 days: little permanent damage.
  • Complete urethral obstruction results in death in 3-5 days.


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Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Caywood D D, Osbourne C A (1986) Surgical removal of canine uroliths. Vet Clin North Am Small Anim Pract 16 (2), 389-407 PubMed.
  • Osbourne C A, Polzin D J (1986) Non-surgical management of canine obstructive urolithopathy. Vet Clin North Am Small Anim Pract 16 (2), 333-347 ScienceDirect.
  • Ibrahim A, Musa B, Zein M (1984) Changes in urinary pH and glomerular filtration rate in partially obstructed canine kidney. J Urol 131 (1), 143-145 PubMed.

Other sources of information

  • Stone E A (1992) Urologic Surgery of the Dog and Cat. Philadelphia: Lea & Febiger.

Related Images


Acid base imbalance


Bladder: herniation

Bladder: neoplasia

Bladder: trauma rupture

Blood biochemistry: overview

Blood biochemistry: potassium

Blood biochemistry: total protein

Blood biochemistry: urea




Cystoscopy: transurethral cystoscopy/vaginoscopy

Cystostomy: tube



Dietetic diet: decreasing risk of cystine stones (uroliths)

Dietetic diet: decreasing risk of oxalate stones (uroliths)

Dietetic diet: decreasing risk of urate stones (uroliths)

Dietetic diet: dissolving and decreasing risk of struvite stones (uroliths)


Dysuria investigation

ECG: overview

Hematology: packed cell volume


Hydronephrosis / hydroureter



Kidney: pyelonephritis

Muscle relaxant: overview




Prostate disease

Prostate flush

Prostate: abscessation

Prostate: benign hyperplasia and hypertrophy

Prostate: neoplasia


Radiography: abdomen

Radiography: double contrast cystography

Radiography: intravenous urography

Radiography: vaginourethrography

Therapeutics: urinary system

Ultrasonography: bladder and urinary tract


Ureter: neoplasia

Ureter: trauma

Ureter: urolithiasis

Urethra: neoplasia

Urethra: obstruction

Urethra: retrograde urohydropulsion

Urethral catheterization: female

Urethral catheterization: male


Urinalysis: bacteriology

Urinalysis: centrifuge sediment

Urinalysis: epithelial cells

Urinalysis: overview


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