Nephroliths may obstruct the renal pelvis or ureter, predispose to
pyelonephritis, or result in compressive injury of the renal parenchyma leading to progressive
chronic kidney disease. Indications for removal of nephroliths in dogs include obstruction,
recurrent infection, progressive
nephrolith enlargement, presence of clinical signs (renal
pain), and patients with nephroliths in a solitary functional kidney. The most common indication for removal of upper tract uroliths in cats is
ureteral obstruction caused by ureteroliths. Nonobstructive nephroliths in cats are not usually treated unless they move into the ureter resulting in
ureteral obstruction. The treatment approach to nephroliths and ureteroliths is different for dogs versus cats. Surgical removal of nephroliths or ureteroliths by
nephrotomy and ureterotomy respectively is associated with potential for complications in more than 30% of cats treated by ureterotomy; therefore, minimally invasive options should also be considered. Extracorporeal
shock wave
lithotripsy (ESWL) treatment of nephroliths results in small "passable" stone fragments in most dogs, whereas ESWL does not work effectively in cats. Ureteral
stents are effective for relief of
ureteral obstruction by ureteroliths in both dogs and cats. Ureteral
stents may be left in place long-term to relieve
ureteral obstruction by ureteroliths. Post-operative morbidity and mortality are substantially lower for ureteral
stent placement compared to open surgical ureterotomy in cats.