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  News from the Maryland Veterinary Medical Association                                                   Winter 2012

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Guess What I Saw?

by Travis Reed, DVM, Surgical Intern
Chesapeake Veterinary Surgical Specialists

An 11 month old, castrated male, domestic shorthaired cat was referred to a veterinary emergency and referral clinic with a primary complaint of urinary blockage. The referring veterinarian (rDVM) had diagnosed a urethral obstruction earlier that afternoon, but could not pass a urinary catheter. Serum biochemical analysis revealed a marked azotemia with BUN > 130 mg/dL (reference range 16-36 mg/dL) and creatinine 11.2 mg/dL (reference range 0.8-2.4 mg/dL); hyperkalemia >10 mmol/L (reference range 3.5-5.8 mmol/L), hyperphosphatemia 13.1 mg/dL (reference range 3.1-7.5 mg/dL); and a mild anemia (Hct = 27.5% [reference range 30-45%]).

Urinary catheterization efforts by the emergency and surgery services were unsuccessful. To empty the urinary bladder a diversionary cystostomy tube was placed on an emergency basis under a brief anesthesia.

The cat was maintained on crystalloid intravenous fluid therapy (0.9% NaCl at 200ml/kg/d weaned down to 134ml/kg/d), a fentanyl constant-rate infusion (CRI; 3mcg/kg/hr), and Timentin (50mg/kg IV q8h) over the next 48 hours until the azotemia and electrolyte abnormalities returned to the reference range.

A contrast cystourethrogram was performed by instilling radiographic contrast material through the cystostomy tube (Figure 1) since a retrograde urethrogram could not be performed due to the inability to catheterize the urethra. The contrast study demonstrated obstruction of the caudal pelvic urethra at the level of the ischium. Definitive surgical correction of the urethral obstruction would entail a urethrostomy. The location of the obstruction was too far cranial for a perineal urethrostomy, however; thus leaving the options of a transpelvic (or transischial), transpubic, or prepubic urethrostomy. The cat was taken to surgery for a transpelvic urethrostomy.

Postoperatively the cat was maintained on maintenance crystalloid intravenous fluid therapy (Isolyte S, 100ml/kg/d weaned down to 66ml/kg/d), a fentanyl CRI (3mcg/kg/hr weaned down to 2mcg/kg/hr), and Timentin for the next 2 days. Urinary diversion through the cystostomy tube was continued for an additional 12 hours before the cystostomy tube was capped. The cat began producing urine through the new urethral stoma with no complications, and he was discharged 2 days postop. The owners were instructed to monitor the cystostomy tube site for signs of infection or damage to the tube, and were provided with a plastic restraint collar for the cat. Discharge medications included buprenorphine (0.01mg/kg PO q8-12h PRN) for analgesia and Clavamox Drops (62.5mg PO q12h).

The cat returned 13 days after definitive surgery for reevaluation, suture removal, and cystostomy tube removal. He was reportedly urinating well at home, and the owners had no concerns. A urine culture collected at surgery resulted in no growth. The cat was reevaluated at 8 weeks post-operatively. He was urinating well, and the owners had no concerns. The urethrostomy stoma had healed well and was of adequate size. This was a satisfactory recheck, and no further follow-ups were needed. The owners were cautioned that the cat might be at risk for urinary tract infections due to the shortened urethra.

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The Maryland Veterinarian invites you to submit an interesting case for our recurring feature "Guess What I Saw!" Highlight your special interest or your practice’s special services, or just tell the readers about a "Gee whiz" case. Electronic submissions should be 750 to 1500 words in length, and use an eye-catching illustration in jpeg format.

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