Passive ureteral dilation and ureteroscopy after ureteral stent placement in five healthy Beagles. 
OBJECTIVE To determine whether passive ureteral dilation (PUD) would occur after an indwelling ureteral stent was left in place in healthy dogs for 2 or 6 weeks, ureteroscopy would be possible at the time of stent removal, and PUD would be reversible after stent removal.  ANIMALS 5 healthy adult female Beagles.  PROCEDURES A ureteral stent was cystoscopically placed in each ureter of each dog with fluoroscopic guidance (week 0).  One stent was removed from 1 ureter in each dog after 2 weeks (ureter group 1), and the other was removed after 6 weeks (ureter group 2); removal timing was randomized.  Computed tomographic excretory urography was performed every 2 weeks from weeks 0 through 10 to measure ureteral diameters.  Ureteroscopy was attempted at the time of ureteral stent removal in each group.  Ureteral diameters were compared among measurement points.  RESULTS The degree of PUD was significant after 2 and 6 weeks of stent placement in both ureter groups.  Mean diameter of the midportion of the ureter in both groups prior to stent placement was 1.70 mm (range, 1.3 to 2.7 mm).  At stent removal, mean diameter of the midportion of the ureter was 2.86 mm (range, 2.4 to 3.1 mm) in group 1 and 2.80 mm (range, 2.1 to 3.4 mm) in group 2.  Ureteroscopy was successfully performed in all dogs up to the renal pelvis.  Compared with week 0 values for diameter of the midportion of the ureter, the degree of PUD induced by stent placement had reversed by week 8 in group 1 (mean diameter, 2.00 mm [range, 1.5 to 2.3 mm]).  CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that ureteral stent placement for 2 weeks would result in sufficient PUD in healthy dogs to allow ureteroscopy at the time of stent removal and that the original ureteral diameter would eventually be restored.  Additional research is needed to determine whether findings would be similar for dogs with urinary tract disease.