Factors Affecting the Outcome of Medical Treatment in Cats with Obstructive Ureteral Stones Treated with Tamsulosin: 70 Cases (2018–2022)

SIMPLE SUMMARY: Other than surgical approaches the treatment options for feline ureterolithiasis are limited compared to those of human medicine. After various studies on ureteral muscle relaxation drugs, tamsulosin has been used as a treatment for distal ureteral stones in human medicine. However, the available clinical veterinary data on the efficacy of drugs that relax the ureter are limited. Thus, this study aimed to investigate the factors affecting the outcome of tamsulosin treatment for feline ureterolithiasis. With tamsulosin treatment, the ureteric stone passage was confirmed in 22 out of 70 cats, with a success rate of 31.43%. Negative factors with statistical significance for stone passage in this study were high baseline creatinine levels, female sex, proximal location of stones, and large diameter stones. The results of this study suggest that tamsulosin can be considered for the treatment of ureterolithiasis in cats with small distal ureteral stones. In addition, this study serves as an important reference for determining whether medical treatment of feline ureteral obstruction using tamsulosin can be attempted. ABSTRACT: The incidence of diseases associated with feline ureteral obstruction is increasing; however, non-surgical treatment options are limited. This study evaluated the outcome of medical treatment in cats with obstructive ureteral stones treated with tamsulosin and identified potential factors predicting spontaneous stone passage. We retrospectively reviewed 70 client-owned cats treated at the Western Referral Animal Medical Center, Seoul, Korea, from 2018 to 2022. All the cats had obstructive ureterolithiasis and were treated using tamsulosin. The baseline characteristics of the cats, stone diameter and location, and stone passage outcomes were analyzed. Stone passage occurred in 22 cats; the remaining 48 cats showed no change in stone locations. Sex, creatinine, and diameter and location of stones were potential risk factors associated with successful stone passage, but age, weight, and side of the stone were not. No serious adverse events related to tamsulosin treatment were observed. This is the first study to identify the risk factors predictive of the spontaneous stone passage of cats with obstructive ureterolithiasis after tamsulosin treatment. Tamsulosin could be an alternative treatment for ureteral obstruction in male cats with smaller distal ureteral stones and low baseline serum creatinine levels. These findings could help develop guidelines for treating feline ureterolithiasis.