Outcome of medical treatments combined with tamsulosin for feline ureteral obstruction.

Surgical treatment options for feline ureteral obstruction are lacking. Based on its use in human medicine, tamsulosin may be a promising candidate. We have accumulated evidence of its extra-label use at our hospital in cases where surgery was declined by the owner. Accordingly, in this single-center, retrospective study, we investigated the responses to tamsulosin in patients with multi-causal feline ureteral obstruction by determining response rates and evaluating the demographic and clinicopathological characteristics of responders. Cats were classified as responders if they showed complete or partial hydronephrosis remission (renal pelvic diameter <50% of the presentation value). We evaluated 62 cats, of which 32 had ureteral calculi (51.6%) and 30 (48.4%) did not. All cats had received 50 μg oral tamsulosin once daily as initial treatment. A total of 30/62 (48.4%) cats were defined as responders, and the response rates were similar irrespective of the presence or absence of ureteral calculi. Body weight was significantly higher in responders than in non-responders. Adverse drug reactions were rare, mild, reversible, and did not include hypotension. The response rate we report for tamsulosin may be of interest to clinicians considering its use in combination therapy where surgery is declined or delayed and for future research on feline ureteral obstruction.