Ureteroliths will sometimes pass into the bladder or move retrograde into the kidney pelvis.50 In some cases, ureterolith passage into the bladder can be facilitated by administering smooth muscle relaxants such as
prazosin (Minipress—Pfizer; 0.25 to 0.5 mg/cat orally twice a day; 1 mg/15 kg orally once or twice a day in dogs), fluid therapy,
and diuretics. Amitriptyline can also be used in dogs for ureteral smooth muscle relaxation (1 to 2 mg/kg orally once a day).
If the ureterolith has not passed from the ureter in three to five days with medical management, surgical intervention or
lithotripsy may need to be considered.
Consider removing an affected kidney and ureter if their function is severely impaired because of a nephrolith and the other
kidney is functioning adequately as demonstrated by the results of laboratory tests and an excretory urogram or nuclear scintigraphy.
Removing a urolith by surgically incising the renal pelvis or ureter is also an option but may cause permanent damage to these
organs. The introduction of a percutaneous approach to surgical incision of the kidney for the purpose of urolith extraction,
lithotripsy, or ureteral stent placement holds promise for decreasing associated damage to the affected area.16,17
In general, nephrotomy and ureterotomy should only be undertaken if the urolith is severely compromising renal function; is
associated with severe pain, hematuria, or infection; or is steadily enlarging and causing obvious damage to kidney tissue.
Otherwise, the best option is often monitoring the patient's status by periodically evaluating the results of serum chemistry
profiles, urinalyses, and abdominal imaging; observing for progressive clinical signs; providing pain management as needed;
and implementing a preventive plan appropriate for the suspected urolith type. The evaluation interval will vary with the
patient's condition. Relatively asymptomatic patients may only require evaluation every two to three months, while patients
exhibiting more clinical signs may warrant daily to weekly evaluation.
Mary Bowles, DVM, DACVIM
Department of Veterinary Clinical Sciences
Center for Veterinary Health Sciences
Oklahoma State University
Stillwater, OK 74078
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