Evaluation of a method of ureteroneocystostomy in cats.

Renal transplantation is a successful treatment for terminal renal failure in cats. Ureteral obstruction at the bladder wall or stoma has been a technical complication encountered in approximately 50% of clinical transplants. The small (0.4 mm) diameter of the feline ureter makes standard techniques described for ureteroneocystostomy unsatisfactory for cats. In this study, we used microsurgical techniques to oppose ureteral mucosa to intact bladder mucosa in an attempt to form a stricture-free stoma. In each of 5 anatomically normal cats, 1 ureter was microsurgically implanted in the bladder. Ultrasonographic examination of the kidneys, ureters, and bladder was performed twice weekly for 8 weeks. Excretory urography was performed at postoperative weeks 1, 2, 4, 8, and 12. Biopsy specimens were taken from the kidney on the surgically treated side 4 weeks after surgery. At 12 weeks, the kidney, ureter, and ureterovesical junction from the treated side were removed and submitted for histologic evaluation. At 1 week, all cats had enlargement of the kidney, renal pelvis, and ureteral lumen on the treated side. This enlargement gradually decreased, and by week 8, there was no difference in comparison with the control side. Ureteroneocystostomy that requires tunneling of the ureter through the bladder wall may result in hydroureter and hydronephrosis, which may resolve. Recognition of these changes may prevent unwarranted surgical intervention in cases of suspected obstruction. The technique described in this study has been used in 15 cats receiving renal allografts. None required surgical correction of ureteral obstruction.