# Successful Treatment of Obstructive Ureterolithiasis with Medical Expulsive Therapy Including Tamsulosin in a Dog

## TL;DR

A 9-year-old Chihuahua successfully passed kidney stones using tamsulosin, a non-surgical treatment, when surgery was not an option.

## Contribution

Demonstrates the effectiveness of tamsulosin in treating obstructive ureterolithiasis in dogs without surgery.

## Key findings

- Tamsulosin facilitated the expulsion of distal ureteroliths within 72 hours.
- Kidney function improved significantly following treatment with tamsulosin.
- Medical expulsive therapy can be a viable alternative to surgery in selected canine cases.

## Abstract

Ureterolithiasis is a common cause of urinary obstruction in dogs and can lead to kidney injury if not treated promptly. Although surgery is usually the treatment of choice, it may not always be possible because of anesthesia risks or financial limitations. In some cases, medical expulsive therapy (MET), such as α-adrenergic antagonists, can help facilitate the passage of ureteroliths. This case report describes a 9-year-old Chihuahua with anorexia, dehydration, and kidney dysfunction caused by obstructive ureteroliths (maximum diameter, 3.31 mm) in the distal ureter. Because surgery was not elected by the owner, the dog was treated with tamsulosin, an α-adrenergic antagonist that relaxes the ureter and facilitates the expulsion of small distal ureteroliths. After treatment, the stones passed within 72 h, and kidney function improved significantly. This report suggests that tamsulosin may be considered a minimally invasive treatment option for obstructive ureterolithiasis in selected dogs for whom surgery is declined due to financial constraints or perceived risk.

Ureterolithiasis is a common cause of ureteral obstruction in dogs, often leading to kidney injury. Medical expulsive therapy (MET) using α-adrenergic antagonists has been proposed as a nonsurgical treatment option in selected cases and is thought to facilitate ureteral stone passage by reducing ureteral smooth muscle tone. A 9-year-old castrated male Chihuahua weighing 1.78 kg was presented with anorexia. Physical examination revealed 7% dehydration and pale mucous membranes. Serum biochemistry demonstrated severe azotemia, with markedly elevated symmetric dimethylarginine (>100 μg/dL; reference interval [RI], 0–14 μg/dL), blood urea nitrogen (157.9 mg/dL; RI, 7–25 mg/dL), and creatinine (2.2 mg/dL; RI, 0.5–1.5 mg/dL). On day 4 of hospitalization, ultrasonography revealed dilation of the renal pelvis (16.1 mm), ureteral distention (3.74 mm), and multiple ureteroliths (maximum diameter, 3.31 mm) at the ureterovesical junction. Antegrade pyelography confirmed a right ureteral obstruction. As the owner declined surgical intervention, MET including tamsulosin, was initiated with close clinical monitoring. After 3 days, improvement in azotemia and resolution of ureteral obstruction were observed. Although concurrent medical treatments were administered, this case provides clinical insight into the potential role of tamsulosin as part of medical management of obstructive ureterolithiasis in a dog with small distal ureteral stones.