Lorazepam for Urethral Obstruction in Cats

In a 2026 JAVMA prospective, randomized, double-blinded, placebo-controlled trial of 80 client-owned male cats with first-time urethral obstruction (72 completing), lorazepam administered for 1 month after hospitalization was associated with zero reobstruction, versus 5 recurrences, all of them in the placebo group. The difference in recurrence rate was statistically significant: 0% on lorazepam (95% CI, 0.0–10.9) versus 15.7% on placebo (95% CI, 5.2–33.7).

Study design and population

• Prospective, randomized, double-blinded, placebo-controlled study at a university teaching hospital; cats were enrolled 2021–2025.
• 80 client-owned male cats with first-time urethral obstruction; cats with urolithiasis or urinary tract infection were excluded.
• Randomization: 41 cats to lorazepam, 39 to placebo; 72 cats completed the study.
• The study drug was administered for 1 month after hospitalization.

Secondary outcomes and safety

Lower urinary tract signs were reduced in the lorazepam group during follow-up: 2 of 33 cats showed signs during days 8–15, and 1 of 31 cats during days 16–30. Ataxia was the only adverse effect that reached statistical significance, occurring in 4 of 31 cats (13%); sedation, increased appetite, and vocalization were also reported.

Authors’ conclusion

The authors concluded that lorazepam administered for 1 month after hospitalization was associated with reduced urethral obstruction recurrence and reduced lower urinary tract signs, and was found to be safe in this population.

Clinical context

This is a single prospective study in male cats with first-time urethral obstruction; cats with urolithiasis or urinary tract infection were excluded. The findings should not be extrapolated to female cats, cats with recurrent obstruction, or cats with confirmed urolithiasis or UTI.

Ask Vetinuity

For follow-up questions about the dosing regimen, safety monitoring, or incorporating lorazepam into an obstruction discharge protocol, ask the Vetinuity clinical assistant.