Detrusor atony in the cat after urethral obstruction
7-year-old neutered male cat that was blocked for about three days. The catheter is removed at 48 h; 12 hours later the bladder is large and flaccid, he dribbles urine and makes hardly any voluntary voids. A catheter passes with no resistance and the urine is clear.
What is the most appropriate interpretation and management?
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A. Re-obstruction by a new plug; urgent perineal urethrostomy is indicated
The catheter passes without resistance and the bladder is flaccid: the urethra is patent. The problem is not the outlet but bladder contraction.
B. Empty the bladder by manual expression several times a day as the main measure
In a recently blocked cat, expression is painful, can trigger urethral spasm and, with a damaged bladder wall, increases the risk of rupture. Emptying it by catheter is preferable.
C. Bethanechol alone, without emptying the bladder, as the drug is enough to restore contraction
If the bladder stays distended, the detrusor fibres do not recover. Bethanechol, with limited evidence, is only an adjunct to emptying.
D. Detrusor atony from overdistension: keep the bladder empty with an indwelling catheter or intermittent catheterisation for a few days and consider bethanechol, after first confirming the urethra is patent
Correct. Prolonged distension disrupts the junctions between detrusor fibres. Keeping the bladder small allows contraction to recover, usually within days. Bethanechol is never given without ruling out obstruction, as it raises pressure inside the bladder.
lightbulb Key takeaway
After a long obstruction, palpate the bladder after each void: if it stays large, detrusor atony may be present. Distinguish atony (catheter passes easily, flaccid bladder) from re-obstruction or urethral spasm (tense bladder, hard to empty).
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Updated: October 31, 2026 · Educational content for veterinary professionals. It does not replace current clinical guidelines or the judgement of the attending veterinarian.