Prazosin Use in Feline Urethral Obstruction

In the Literature

Reineke EL, Thomas EK, Syring RS, Savini J, Drobatz KJ. The effect of prazosin on outcome in feline urethral obstruction. J Vet Emerg Crit Care. 2017;27(4):387-396.

The Research …

Feline urethral obstruction is common in veterinary medicine, and recurrence rates of 14% to 57% have been reported.^1-4 Although therapeutic techniques have evolved, no reliable method or medication has been proven to prevent recurrent feline urethral obstruction (rFUO). In 1971, an observational study discussed an escalating approach to therapy, which included IM injections of pancreatic extract, antibiotic administration, and digital and needle manipulation of the urethra.⁵ Since then, reports have documented use of intravesicular lidocaine, intravesicular and oral glycosaminoglycans, phenoxybenzamine, and prazosin in the prevention of rFUO.^2,6-9

Prazosin, an α1-adrenergic blocker, acts as a smooth muscle relaxer and is labeled for the treatment of hypertension in humans. Its use in the treatment of benign prostatic hyperplasia is extra-label and, in veterinary medicine, is prescribed for the prevention of feline urethral obstruction and rFUO.⁹ No pharmacokinetic information on prazosin in cats has been reported, and recommended doses range from 0.25-1 mg/kg PO q12h.⁹ Until this study was published, there had only been weak evidence in the form of retrospective studies without control subjects describing the use of prazosin in cats with rFUO, and small studies have reported mixed information regarding prazosin’s efficacy in preventing rFUO.^3,10,11 

This article prospectively examined whether prazosin at 0.25 mg/cat PO q12h affected rFUO rates. No significant side effects or reduction in rFUO rates were noted in 47 male cats (27 receiving prazosin, 20 receiving placebo) observed for one month. Studies using larger test and control groups are needed to determine statistically relevant differences.

… The Takeaways

Key pearls to put into practice:

• Prazosin at 0.25 mg/cat PO q12h does not appear to have clinically relevant side effects.

• Based on the study findings, prazosin does not appear to prevent rFUO.