Canis ISSN: 2398-2942

Urinary obstruction

Contributor(s): Lori Ludwig

Introduction

  • Cause: urolithiasis or mass.
  • Signs: dysuria.
  • Diagnosis: signs, imaging.
  • Treatment: catheterize or surgically remove obstructions.
  • Prognosis: dependent on underlying cause:
    • Neoplasia (grave).
    • Urolithiasis (good if treatment initiated promptly).

Pathogenesis

Etiology

  • Intraluminal: urolithiasis Urolithiasis.
  • Intramural:
    • Tumors of ureter Ureter: neoplasia (rare).
    • Tumors of urethra, ie TCC.
    • Tumors of bladder neck.
    • Obstructive urethritis.
    • Stricture from previous trauma/surgery.
  • Extramural:
    • Abdominal tumors.
    • Trauma - ligation during ovariohysterectomy.
    • Uterine stump infections Pyometra.
    • Prostatic disease, eg neoplasia, abscess.

Predisposing factors

General
  • Male dogs more frequently obstruct secondary to urolithiasis.
  • Struvite urolithiasis most commonly associated with infection.
  • Urethral neoplasia is more common in female dogs.
  • Specific breed disposition, eg Dalmation/urate, for urolithiasis.

Pathophysiology

  • Urethral obstruction commonly occurs in dogs as a result of urolithiasis, neoplasia or trauma.
  • Acute obstruction is seen most commonly in male dogs due to obstruction by calculi lodged at the base of the os penis.
  • Prolonged ureteric obstruction (>7 days) → 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.
  • Complete urethral obstruction can result in hydroureter, hydronephrosis, and bladder rupture → azotemia, hyperkalemia, acidosis.

Timecourse

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

Diagnosis

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Treatment

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Outcomes

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Further Reading

Publications

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.


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