Surgery of the Feline Ureter

Urolithiasis in cats Calcium oxalate (CaOx) containing uroliths are the predominant stone type identified in the ureter of cats. Unfortunately, medical dissolution of CaOx uroliths is not available and so surgical removal or the placement of a ureteral stent is often recommended if the stones are causing clinical disease. If intervention is necessary, it is not always clear how long one should wait to address ureteral uroliths. Surgery is indicated in cases of worsening ureteral obstruction, known impairment of normal renal function, or the presence of a secondary infection that doesn’t respond to medical therapy. Factors that also need to be considered with regards to prognosis include the function of the contralateral kidney and the overall health of the patient. The ability of the feline kidney to recover from partial or complete outflow obstruction is unknown. Recovery of renal function generally depends on the severity and duration of the obstruction and the presence of pre-existing renal disease. Unfortunately, in cases of unilateral ureteral obstruction, a diagnosis may go undetected if function in the opposite kidney is normal. Cats with uroliths affecting the ureter can present asymptomatic or with non-specific clinical signs including lethargy, weight loss, anorexia, vomiting, fever and polydipsia and polyuria. Hematuria may or may not be present. Patients may also present with abdominal pain and splinting or renomegaly. A complete physical examination is performed, as many affected cats are older and may have concurrent disease(s). A urinalysis, complete blood count, biochemical profile, and plain abdominal radiographs are usually recommended as initial investigative steps. Uroliths are often visualized on plain radiographs, although small ureteroliths, radiolucent ureteroliths, or those overlying colonic contents are occasionally missed. Further imaging studies including ultrasonography, excretory urography, antegrade pyelography and computed tomography are often helpful in identifying small ureteroliths, the presence of hydronephrosis and hydroureter, as well as delineating the level of a ureteral obstruction. It is important to note that ureteral dilation identified using one of these modalities does not always extend to the level of the obstruction. Ureteral surgery in cats generally requires substantial magnification. The author recommends 8 to 10 times magnification provided by an operating microscope. Stones in the proximal ureter are removed by ureterotomy or a pyelotomy. Uroliths may be visible on