Page 1182 - Clinical Small Animal Internal Medicine

1120 Section 10 Renal and Genitourinary Disease

ureter makes even small stone fragments problematic An indwelling ureteral stent is composed of a flexible
VetBooks.ir and even in dogs there is risk of ureteral obstruction after polymeric compound that has a loop at each end, which
help maintain the stent’s position throughout the ureter,
shock wave therapy of nephroliths. The likelihood of
ureteral obstruction following shock wave therapy can be
bladder. Ureteral stents may be placed endoscopically,
limited if a ureteral stent is implanted at the time of the with one loop in the renal pelvis and the other in the
shock wave treatment. Extracorporeal shock wave litho­ though this is most feasible in female dogs where a rigid
tripsy is a consideration for dogs and appears well toler­ cystoscope and a comparatively larger urethra facilitate
ated, though transient hematuria or shock wave‐induced the procedure. For cats, the stents are typically placed via
pancreatitis may occur. an open abdominal procedure with fluoroscopic guid­
In dogs, surgical ureterotomy for an obstructive uro­ ance. The stent may be placed antegrade through the
lith is typically associated with a favorable outcome in renal parenchyma after needle access into the renal pel­
the hands of an experienced surgeon. In cats, however, vis, or retrograde through a cystotomy incision and visu­
major complications were reported in a significant num­ alization of the ureterovesicular orifices. Reports of
ber of the cases, with a mortality rate of 18% in the larg­ ureteral stents in both dogs and cats suggest successful
est series from a highly experienced center. In light of implantation in greater than 95% of cases with low com­
these figures, alternatives to surgical ureterolith removal plication or reintervention rates. The cat shown in
have been developed in recent years, including ureteral Figure 122.10 presented with a BUN of 280 mg/dL (refer­
stenting (Figure 122.10) and subcutaneous ureteral ence interval, 13–30 mg/dL) and a creatinine of 20.5 mg/
bypass (Figure 122.11). gL (reference interval, 0.9–2.1 mg/dL) and complete

Figure 122.10 Radiographic images from a cat with complete right ureteral obstruction secondary to a circumcaval ureter and
ureterolithiasis. A double‐pigtail ureteral stent has been implanted in the obstructed right ureter to restore urine flow. Note that the left
kidney is severely shrunken and small.

Figure 122.11 Radiographic images from a cat with a subcutaneous ureteral bypass system. The system includes a nephrostomy tube
and a cystostomy tube connected to a dual‐lumen vascular port that is sutured to the body wall under the ventral skin.