Update on Prazosin’s Use against Recurrent Urethral Obstruction

Urethral obstruction is a relatively common occurrence in male cats. Prazosin has been used for several disease states including hypertension, congestive heart failure (CHF) and urethral obstruction. Prazosin is an alpha receptor blocker, commonly found in blood vessels and the urethra that works to relax those respective areas. 

More research needs to be made for conclusive evidence but recurrent urethral obstruction was found at a higher rate with prazosin than placebo during a recent study that should at the very least provoke questions. In Conway et al, 388 cats were split roughly 3:1 in groups of cats receiving prazosin versus not. After 14 days of treatment, 24% of cats reobstructed as compared to 13% in group without prazosin. Alternative treatment options to consider include reduction of inflammation with NSAID’s, increased water consumption and dietary adjustments. 

While efficacy may be in question for urethral obstruction, prazosin is a viable treatment option for cardiovascular issues such as congestive heart failure and hypertension. Potential side effects of prazosin include nausea, constipation, lethargy, drowsiness and postural hypotension. If possible, give medication with food. Call your local compounding pharmacist at Pharmacy Solutions for dosing considerations.

Dosing considerations:
Hypertension/CHF in dogs: 1-2mg 2-3 times per day based off weight.
Urethral resistance in cats: 0.5mg PO every 8 hours with considerations made above