The efficacy of administration of prazosin in reducing the risk of recurrent urethral obstruction in male cats.

PICO question: In male cats presenting with urethral obstruction, does administration of prazosin compared with no administration of prazosin reduce the incidence of recurrent urethral obstruction within the first month of initial presentation? Clinical bottom line: Category of research: Treatment. Number and type of study designs reviewed: A total of three studies were included in this appraisal. Two of which were prospective double-blind clinical studies and one retrospective study. Strength of evidence: Weak. Outcomes reported: Both double-blind studies found no significant difference between prazosin administration and the development of recurrent urethral obstruction (rUO) when compared with a placebo. Both studies, however, did report that cats had a shorter urinary catheterisation time with prazosin administration. The retrospective study found no association between prazosin administration and the risk of rUO and found that after 14 days post discharge, significantly more 73/302 (24%) cats that received prazosin had experienced rUO compared to 11/86 (13%) of cats that did not. One study found side effects to the administration of prazosin which may be detrimental to the overall recovery. Conclusion: Administration of prazosin does not reduce the risk of rUO within 30 days of presentation. However, the strength of evidence is weak and would benefit from further clinical studies.