Page 1215 - Clinical Small Animal Internal Medicine

123 Urolithiasis in Small Animals 1153

only one cat had complete resolution of the ureterolith, days after the procedure and collected in a strainer or
VetBooks.ir and partial fragmentation occurred in two other cats; cheesecloth to be analyzed. Animals with ureteral stents
often require shorter hospital stays, as the concern for
however, these fragments were still too large to pass
down the ureter. In the authors’ (AB) experience, suc­
are discharged with instructions for monitoring urina­
cess in stone fragmentation and passage was seen in post‐ESWL ureteral obstruction is diminished. Patients
two of an additional five cats, suggesting an approxi­ tion and urine appearance, lethargy, abdominal pain, or
mate 30% passage rate overall (3/10). However, larger vomiting. Follow‐up radiography and ultrasonography
studies are needed to confirm these results and this are typically recommended one day after treatment, then
procedure is not currently recommended in cats by the in 2–4 weeks, and then every month thereafter until all
authors. stones are passed. If fragments that have passed into the
Extracorporeal shock wave lithotripsy is believed to be urinary bladder are not voided within 1–2 months after
safe and well tolerated by canine kidneys. In a series of ESWL, VUH or cystoscopic stone basketing is recom­
140 dogs with nephroliths or ureteroliths treated by mended. If stone fragments remain in the kidney or ure­
ESWL, the most common complication was ureteral ter after 2–3 months, repeat ESWL is suggested as long
obstruction by stone fragments, which occurred in as there is no concurrent ureteral obstruction. A second
approximately 10% of dogs. With the advocacy of ure­ treatment is required in 15–35% of cases to achieve
teral stent placement for larger nephroliths (>10–20 mm) effective fragmentation if the remaining fragments
before ESWL, this risk has declined. In dogs, it has been appear too large to safely pass through the ureter. In
shown that the renal changes observed after ESWL typi­ cases of ureteral obstruction, placement of a ureteral
cally result in minimal decreases in GFR and renal blood stent would be recommended.
flow during the first 24 hours of treatment, and both
return to baseline within one week. Extrarenal complica­ Ureteral Stents
tions with ESWL include abdominal pain, diarrhea, and The use of ureteral stents in dogs and cats has been
pancreatic injury (i.e., increased enzymes levels not asso­ investigated for the last 14 years as a less invasive alter­
ciated with clinical signs). Shock wave‐induced dysrhyth­ native to traditional surgery. Placement of a double‐pig­
mias have been described in a few human patients (<8%). tail ureteral stent (Figure 123.18), via either minimally
Hospitalization typically ranges from eight to 24 hours invasive techniques (endoscopy and fluoroscopy in most
to monitor for the passage of urolith fragments and to dogs) or surgically assisted (nephrostomy access in most
allow postprocedure analgesia and diuresis with intrave­ cats), can circumvent many of the perioperative compli­
nous fluid therapy. Stone fragments may be voided 1–2 cations of surgery (e.g., leakage, stricture, reobstruction)

(a) (c)

(b)

Figure 123.18 Preoperative lateral (a), postoperative lateral (b) and ventrodorsal (c) radiographs following ureteral stent placement in a cat.