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



Open Access Logo



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



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



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.



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.


How to apply this evidence in practice

The application of evidence into practice should take into account multiple factors, not limited to: individual clinical expertise, patient’s circumstances and owners’ values, country, location or clinic where you work, the individual case in front of you, the availability of therapies and resources.

Knowledge Summaries are a resource to help reinforce or inform decision making. They do not override the responsibility or judgement of the practitioner to do what is best for the animal in their care.


Conway, D.S., Rozanski, E.A. & Wayne, A.S. (2022). Prazosin administration increased the rate of recurrent urethral obstruction in cats: 388 cases. Journal of the American Veterinary Medical Association. 260(S2), 1–6. DOI:

Corgozinho, K.B., de Souza, H.J.M., Pereira, A.N., Belchior, C., da Silva, M.A., Martins, M.C.L. & Damico, C.B. (2007). Catheter-induced urethral trauma in cats with urethral obstruction. Journal of Feline Medicine & Surgery. 9(6), 481–6. DOI:

Hanson, K.R., Rudloff, E., Yuan, L., Mochel, J.P. & Linklater, A.K. (2021). Effect of prazosin on feline recurrent urethral obstruction. Journal of Feline Medicine & Surgery. 23(12), 1176–1182. DOI:

Hetrick, P.F. & Davidow, E.B. (2013). Initial treatment factors associated with feline urethral obstruction recurrence rate: 192 cases (2004–2010). Journal of the American Veterinary Medical Association. 243(4), 512–519. DOI:

Kyles, A.E., Hardie, E.M., Wooden, B.G., Adin, C.A., Stone, E.A., Gregory, C.R., Mathews, K.G., Cowgill, L.D., Vaden, S., Nyland, T.G. & Ling, G.V. (2005). Clinical, clinicopathologic, radiographic, and ultrasonographic abnormalities in cats with ureteral calculi: 163 cases (1984–2002). Journal of the American Veterinary Medical Association. 226(6), 932–936. DOI:

Reineke, E.L., Thomas, B.A., Syring, R.S., Savini, J. & Drobatz, K.J. (2017). The effect of prazosin on outcome in feline urethral obstruction. Journal of Veterinary Emergency and Critical Care. 27(4), 387–396. DOI:

Straeter-Knowlen, I.M., Marks, S.L., Rishniw, M., Speth, R.C., Wirth, W. & Knowlen, G.C. (1995). Urethral pressure response to smooth and skeletal muscle relaxants in anesthetized, adult male cats with naturally acquired urethral obstruction. American Journal of Veterinary Research. 56(7), 919–923.





Vol. 8 No. 4 (2023): The fourth issue of 2023

Section: Knowledge Summaries

Categories :  Small Animal  /  Dogs  /  Cats  /  Rabbits  /  Production Animal  /  Cattle  /  Sheep  /  Pig  /  Equine  /  Exotics  /