Lorazepam reduces recurrence of urethral obstruction in male cats: a prospective, randomized, double-blinded,...

To determine the efficacy of lorazepam in reducing the rate of recurrence in first-time feline urethral obstruction (UO) and frequency of lower urinary tract (LUT) signs following hospitalization, as well as adverse effects of the medication.

This was a prospective, randomized, double-blinded, placebo-controlled study of 80 client-owned male cats presenting to a university teaching hospital with UO between 2021 and 2025. Cats with urolithiasis or urinary tract infection were excluded. Cats received lorazepam or placebo for 1 month after hospitalization for UO.

41 cats received lorazepam and 39 cats received placebo. Seventy-two cats completed the study. Five of 72 cats experienced recurrence of UO, all receiving placebo. No cats receiving lorazepam had UO recurrence (0%; 95% CI, 0.0% to 10.9%) compared to the placebo group (15.7%; 95% CI, 5.2% to 33.7%); this was statistically significant. There was a statistically significant reduction in LUT signs for 2 of 33 cats during days 8 to 15 (95% CI, 0.7% to 20.2%) and 1 of 31 cats during days 16 to 30 (95% CI, 0.1% to 16.7%) for the lorazepam group. Ataxia was the only statistically significant side effect of lorazepam, occurring in 4 of 31 cats (13%); other reported effects included sedation, increased appetite, and vocalization.

Lorazepam administration was associated with a reduction in the recurrence of UO in this study population, as well as reduced LUT signs compared to cats receiving placebo. Lorazepam administration was found to be safe.

Lorazepam may be used safely in the reduction of both recurrent UO and LUT signs following alleviation of UO in male cats.