• 1. When discussing the option of surgery to remove uroliths from the lower urinary tract, clients should be informed that even in the hands of experienced surgeons, there is a risk that not all uroliths will be removed. Therefore, appropriate radiographs will be evaluated following surgery. Clients also should be informed of the consequences of incomplete removal of uroliths, and the benefits and risks of therapeutic strategies available to manage this complication.
• 2. Uroliths often migrate to lower portions of the urinary tract. Therefore, if several days have elapsed between the date of diagnostic radiography and/or ultrasonography and the date of surgery scheduled to remove the uroliths, the number and location of stones should be re-evaluated by appropriate imaging methods just prior to surgery.
• 3. Appropriate caution should be taken to remove all uroliths from the bladder lumen, bladder neck and urethra. When possible, the number of uroliths removed from the lower urinary tract should be compared with the number of uroliths detected by radiography, ultrasonography or via cystoscopy. Uroliths may be removed with the aid of spoons, forceps, gauze sponges or suction devices. The lumen of the bladder and bladder neck should be explored with a finger to detect remaining uroliths.

In addition, the bladder lumen should be flushed with an isotonic solution to remove subvisual uroliths. Uroliths that have passed into the urethral lumen may be flushed back into the bladder lumen by injecting appropriate quantities of physiological saline through a catheter placed in the external urethral orifice. The external urethral orifice should be occluded around the catheter to facilitate flushing of the urethroliths back into the bladder lumen. If the distal urethra is not occluded, fluid may flow around small urethroliths without moving them into the bladder lumen. This will result in incomplete removal of uroliths.

If retrograde flushing techniques are used to flush urethroliths into the bladder with the aid of a catheter inserted into the distal urethral orifice, appropriate caution must be used to minimize retrograde flushing of bacteria that normally colonize the mucosa of the distal urethra and genital tract into the urinary bladder and surgical site. Inserting a flexible catheter through its lumen via the urinary bladder also may enhance patency of the urethra. Injection of an isotonic solution through the catheter may force uroliths out of the distal urethral orifice. In some cases, it may be of value to check for uroliths by digital palpation of the urethra per rectum. Appropriate precaution should be used to avoid contamination of the surgical site.

If uroliths remaining in the lower urinary tract following surgery are first detected by radiography or ultrasonography several weeks following surgery, it may be erroneously assumed that the patient is highly predisposed to recurrent urolithiasis.

Dr. Osborne, a diplomate of the American College of Veterinary Internal Medicine, is professor of medicine in the Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Minnesota.

Dr. Lulich, a diplomate of the American College of Veterinary Internal Medicine, is a professor in the Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Minnesota.