VSCD profiles interesting and instructive cases and pet owner stories as they present.

Microscopic Ureter Surgery Canidates

Name: Cleopatra Breed: Himalayan Age: 10 years Condition: Renal Failure

“Bella” is a 3 year old spayed female Siamese cat who presented with a history of acute onset of frequenting the litter box, straining to urinate and producing small drops of bloody urine.  Radiographs and ultrasound diagnosed bilateral hydronephrosis and hydroureter secondary to ureteral stone obstruction.  Significant laboratory values included BUN of 126 and creatinine of 10.6.

“Cleopatra” is a 10 year old spayed female Himalayan cat who presented with a history of chronic renal failure with acute decompensation.  Ultrasound revealed left unilateral hydronephrosis and hydroureter seconday to ureteral stone obstruction.  Relevant laboratory values included BUN of 62 and creatinine of 5.2.

Though their presentation differed both cats were successfully treated with microscopic ureter surgery by Dr. Carlson.

These patients underscore the need to perform thorough diagnostics when assessing kidney disease. Bilateral ureteral stones (which are almost always composed of calcium oxalate) may be present in as many as 25% of cats affected with chronic renal failure.  Partial or complete ureteral obstruction will lead to the progressive loss of nephrons and consequent renal function: because it essential that every effort be made to preserve nephrons in these patients both the obstruction and/or the underlying disease process must be addressed.  Fixing the obstruction does not fix the underlying disease process.  Since obstructive nephropathy is potentially correctible, it is important to recognize its occurrence before extensive and irreversible renal damage takes place.  Other factors to consider include:

• Many cats with chronic kidney failure demonstrate relatively stable renal function over time: progressive declines in these values should prompt investigation of ureteral obstruction.
• The principle concern in managing uroliths in cats with renal disease is to minimize the risk that the urolith may cause further loss of renal function.
• Over time, the reversibility of obstructive renal injury declines: early detection maximizes the value of surgical intervention.
• In general, ureteroliths that are not associated with urinary obstruction and do not cause clinical signs can be left in place but should be monitored. 
• Nephroliths, however, are rarely associated with obstruction unless they move into the ureter and most remain within the renal pelvis.
• Not every ureterolith requires surgical intervention.  Some will move down the ureter and ultimately exit to the bladder.  Evidence of progressive movement toward the bladder, with stable renal function, generally suggests delaying surgery.  
• Surgical intervention should be based on contemporary alterations in renal structure and function using serial laboratory diagnostics and ultrasonography.  If surgery is indicated, the precise technique is dictated by the location of the stone within the ureter.

For more information on these cases or ureter surgery in general please contact Dr. Carlson.

Kimberly R. Carlson, DVM
Diplomate of the American College of Veterinary Surgeons