Contributors: Andrew Gardiner, Melissa Wallace, Aidan B McAlinden

 Species: Feline   |   Classification: Diseases

Introduction Pathogenesis Diagnosis Treatment Outcomes Further Reading


  • Causes: urolithiasis, urethral plugs, trauma, neoplasia, extra-urethral mass, idiopathic inflammation, iatrogenic intervention.
  • Signs: straining (stranguria)   Urination: cat straining to urinate  and difficulty associated with urination/variable flow.
  • Diagnosis: clinical signs and physical examination.
  • Treatment: priority is to correct metabolic abnormalities and stabilize animal prior to definitive management.
  • Prognosis: depends on cause and extent of renal damage.
Use the interactive tools from ROYAL CANIN® UK    to explain cat anatomy and disease conditions to your client. Visit ROYAL CANIN Natom Explorer to find out more.

Presenting Signs

  • Difficulty and straining associated with urination Urination: cat straining to urinate .
  • Variable urine flow.
  • Hematuria Hematuria.
  • Signs may be interpreted as straining to defecate by some owners.

Chronic untreated case

  • Depression.
  • Lethargy.
  • Coma.
  • Vomiting.

Acute Presentation

  • Extreme discomfort - distended bladder.

Special Risks

  • Prolonged obstruction   →   hyperkalemia   →   cardiac arrythmias .




  • Urolithiasis: structure of male urethra.


  • Feline urethral obstruction is (unlike canine) often complete and is an urgent situation.
  • Most obstructions occur at the distal penile urethra or the membranous urethra.
  • Obstruction of normal flow of urine leads to:
    • Dilation of kidney calyces and collecting ducts: reduced renal blood flow and glomerular filtration rate.
    • Impaired excretion: azotemia Azotemia, hyperkalemia Hyperkalemia, metabolic acidosis Acid base imbalance.
    • Increased pressure: renal ischemia with or without superimposed infection; permanent kidney damage (severity depends on degree, duration and level of obstruction with or without presence of infection.).
  • Hyperkalemia may   →   cardiac arrythmias   →   death.


  • Bladder distention will reach critical proportions within hours of a complete blockage.


Presenting Problems

Client History

  • Difficulty and straining (stranguria, dysuria) associated with urination.
  • Variable urine flow: may cease midstream, continuous slow dribble, non-productive.
  • Bleeding from urethra.
  • Hematuria.
  • Increased frequency of micturition/attempts to urinate.
  • Frequent licking of genital area.
  • Urination in abnormal places.
  • Vomiting.
  • Depression.
  • Coma.

Clinical Signs

  • Distended bladder palpable; cannot express urine with gentle pressure.

Diagnostic Investigation


  • Urethral catheterization Urethra: catheterization reveals level of obstruction and often allows relief of obstruction by retrohydropulsion.


  • See abdominal radiography Radiography: abdomen.
  • Presence of radiopaque calculi Bladder: calculi - cystogram  Urethra: urolith 01 - radiograph lateral  Urethra: urolith 02 (close-up) - radiograph lateral .
  • Extra-urethral mass.

Contrast radiography

2-D Ultrasonography


Differential Diagnosis


Initial Symptomatic Treatment

  • Place intravenous catheter and start IV fluid therapy (eg 0.9% saline).
  • Correct acid/base, electrolytes Fluid therapy: for acid-base imbalance Fluid therapy: for electrolyte abnormality.
  • Tranquilize or anesthetize (as high risk patient). Anesthesia preferred as it provides better urethral relaxation.
  • Attempt to pass a urethral catheter:
    • An end-opening, non traumatic catheter should be used.
    • Ideally 3.5 F.
    • Extrude penis and place catheter in penile tip.
    • Gently extend penis in caudal and dorsal direction - this will straighten the urethra and ease passage of the catheter.
    • Flush catheter with sterile saline and attempt to advance it.
    • Gentle urethral massage per rectum can sometimes assist in displacing a urolith/urethral plug.
    • If the catheter cannot be advanced retrograde urohydropulsion can be attempted.
    • Gently occlude the urethra proximal to the obstruction per rectum.
    • Infuse saline until the urethra distends under pressure.
    • Release the occlusion to help flush urolith/plug into the bladder.
  • If urethral catheterization fails, drain urinary bladder by cystocentesis Cystocentesis and attempt to relieve urethral obstruction again.
  • If urethral catheterization fails, consider temporary tube cystostomy to drain bladder Cystostomy: tube.

Standard Treatment

  • Stabilize animal.
  • Place urethral catheter Urethra: catheterization.
    There is some controversy about whether this should be left in situ.
  • If leaving a catheter in situ then it should be exchanged for one of a soft silicon variety.
  • See Urolithiasis Urolithiasis.


  • Body temperature.
  • Fluid balance.
  • Electrolytes, acid/base.
  • Azotemia.

Subsequent Management


  • Urinary bladder size.
  • Fluid balance, electrolytes, acid/base.
  • Azotemia.
  • Urine output.



  • Good prognosis for early treatment.
  • Urolithiasis has a high incidence of recurrence, without dietary changes.

Expected Response to Treatment

  • Ability to pass urine normally.
  • Resolution of uremia and electrolyte abnormalities if present.

Reasons for Treatment Failure

  • Delayed treatment allowing renal failure to develop lin Kidney: acute renal failure.
  • Inability to remove blockage.
  • Stenosis recurring at site of trauma, urolith, or urethral tear.

Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Gerber B, Eichenberger S & Reusch C E (2008) Guarded long-term prognosis in male cats with urethral obstruction. J Fel Med Surg 10 (1), 16-23 PubMed.
  • Lee J A & Drobatz K J (2003) Characterization of the clinical characteristics, electrolytes, acid-base, and renal parameters in male cats with urethral obstruction. J Vet Emerg Crit Care 13 (4), 227-33 VetMedResource.
  •  Foster S F, Hunt G B & Malik R (1999) Congenital urethral anomaly in a kitten. J Feline Med Surg (1), 61-64 PubMed.

Other Sources of Information