Feline Urate Uroliths

A renal tubular reabsorptive defect and portovascular anomalies have been incriminated as causes of ammonium urate uroliths.  The causes in most cats, however, have not been established.

Protocols designed to consistently dissolve ammonium urate uroliths in cats have not yet been developed.  Surgery remains the most reliable way to remove active uroliths from the urinary tract.

To minimize stone recurrence or further growth, we recommend the following:

• Perform appropriate diagnostic studies including contrast radiography to identify location and size of uroliths, or post-surgical radiographs to determine efficacy of surgical removal.

• Perform appropriate laboratory tests to determine if portal vascular anomalies are the underlying cause for the uroliths (eg. provocative serum bile acid tests).

• Provide diets low in purine precursors, that promote less acidic urine (pH +7.0) and less concentrated urine.

• Encourage additional water consumption or feed a canned diet to promote diuresis.

If uroliths should recur despite control of risk factors, they may be removed non-surgically by voiding urohydropropulsion if detected early.  Uroliths removed by voiding urohydropropulsion should be quantitatively analyzed.  If attempts at non-surgical urolith removal are unsuccessful, surgery remains the most reliable way to remove active uroliths from the urinary tract.  We emphasize, however, that surgery may be unnecessary for clinically inactive urate uroliths. 

All prevention recommendations should be adjusted to meet individual patient's needs.  We recommend follow-up urinalyses, serum chemistry profiles, and radiographs on a
periodic basis.