Urethral obstruction — a blocked urethra preventing urine passage — is one of the most urgent veterinary emergencies in cats. Affecting almost exclusively male cats due to their narrower urethra, it is life-threatening within 24–48 hours without treatment. Immediate recognition and emergency veterinary care are essential for welfare.
Causes
The most common causes of feline urethral obstruction include:
- Urethral plugs — accumulations of protein, inflammatory cells, crystals, and debris; most common cause in younger cats
- Calcium oxalate or struvite uroliths (bladder stones) lodging at the urethropelvic junction
- Urethral spasm from inflammation (urethritis) without physical obstruction
- Urethral strictures from scarring (recurrent obstructions)
Predisposing factors include indoor lifestyle, obesity, stress, dry food diets, and reduced water intake.
Clinical Signs — Recognising the Emergency
- Repeated trips to the litter tray producing little or no urine — often confused by owners with constipation
- Straining and crying in the tray
- Haematuria (blood in urine) — may have been present for days before obstruction
- Lethargy, vomiting, and inappetence as uraemia develops
- Abdominal pain — tense, firm abdomen
- In late stages: hypothermia, bradycardia, and collapse — severe uraemia and hyperkalaemia
Emergency Treatment
Immediate veterinary intervention is required:
- IV fluid therapy and electrolyte stabilisation before or simultaneous with unblocking
- Sedation or general anaesthesia for urethral catheterisation
- Retrograde flushing of the urethra to dislodge the obstruction
- Urinary catheter left in place for 24–48 hours to allow urethral inflammation to subside
- Monitoring for post-obstructive diuresis — cats produce large volumes of dilute urine after unblocking requiring continued IV fluid support
Welfare and Prevention
Urethral obstruction causes acute, severe suffering — distension of the bladder is intensely painful. Prevention is far preferable to emergency treatment:
- Increased water intake through wet food, water fountains, or multiple water stations
- Stress reduction (FELIWAY, appropriate resource provision in multi-cat households)
- Weight management in obese cats
- Prescription urinary diets for cats with recurrent FLUTD
- Perineal urethrostomy (surgical widening of the urethra) for cats with recurrent obstructions