Screen Shot 2020-04-29 at 1.19.07 PM.png — Bilateral Ureterolithiasis in a Cat

Dr. Anne Desrochers

Patient Information:

Age: 7-year old
Gender: Neutered Male
Species: Feline
Breed: Domestic Short Hair

History:

The patient presented for chronic intermittent vomiting and weight loss (3.5lbs in 9months). Bloodwork revealed azotemia and mild anemia -SDMA 26ug/dL (normal: 0-14), BUN 58mg/dL (normal:16-37), creatine 3.9mg/dL (normal: 0.9-2.5), HCT 28.9%. Abdominal ultrasound was recommended.

Ultrasound Interpretation:

Mild renal enlargement was seen bilaterally (LT/RT: 4.8/4.3cm in length - normal renal size 3.2cm to 4.2cm; Renal Size in Cats, JAVMA, July 2005, Vol 225, Biller). Moderate to severe dilation of the renal pelvis (LT/RT: 10.0/6.0mm) with secondary compression of the medulla was imaged bilaterally consistent with hydronephrosis (> 6mm). In addition, mild to moderate dilation of the proximal right and left ureter was visualized (LT/RT: 4.6/4.0mm). The presence of a hyperechoic semi-circular structure casting strong acoustic shadow was seen in the proximal portion of both ureters consistent with obstructive uroliths measuring 2.7x4.4mm in diameter on left and 2.0x6.8mm in diameter on the right. Two hyperechoic circular structures casting strong acoustic shadows were also imaged in the gravity-dependent portion of the urinary bladder consistent with cystoliths measuring 4.6x5.3mm and 3.0x3.2mm in diameter.

Diagnosis:

Bilateral obstructive ureterolithiasis causing bilateral hydronephrosis and cystolithiasis.

Case Management:

The patient was referred to the surgery services for bilateral subcutaneous ureteral bypass (SUB) placement to address the ureteral obstructions and cystotomy for cystoliths removal. The uroliths were mainly composed of calcium oxalate monohydrate and no growth was obtained on urine culture.
The goal of the SUB is to allow urine to progress from the kidney to the urinary bladder without passage through the obstructed ureter. Potential short- and long-term complications of this surgical procedure include those associated with general anesthesia, in addition to dehiscence, uroabdomen/urine leakage into the subcutaneous space, reobstruction due to kinking or clogging of the tubing and recurrent infections associated with the implant which may lead to pyelonephritis. Following placement of the SUB, long-term management is necessary to ensure patency of the system which includes periodic ultrasound-guided SUB ﬂushing, typically starting 1 month post-operatively, then every 3 months for 1 year, and then every 6-months following.

Outcome:

The patient recovered well from surgery with medical therapy, supportive care and dietary change to a prescription urinary diet. Assessment of the SUB systems a month post-operatively showed normal patency bilaterally. Repeat bloodwork revealed SDMA 25 ug/dL, BUN 70mg/dL, creatinine 4.5mg/dL and no bacterial growth was obtained on repeat urine culture.

The SUB procedure is not intended to resolve the underlying renal disease and worsening of the renal values may occur initially due to the injury sustained from the acute obstruction of the ureters and the surgical procedure itself. More time is needed to determine the extent of the residual renal disease but the patient will likely necessitate long-term management of the chronic renal disease.