Department of Small Animal Clinical Sciences, University of Florida, Gainesville, FL, USA
Uretrostomia en Perro y Gato
First reported in the 1990s, feline ureteral obstructions are becoming increasingly more common. The exact etiology is unknown but it may be secondary to increased owner awareness, availability of advanced diagnostics, and dietary and hereditary factors. Causes of obstruction include calcium oxalate, neoplasia, stenosis, iatrogenic ligation, blood calculi, and blood clots. Treatment options vary and depend on available equipment, surgeon experience, patient status, and owner finances. Measures in treating a ureteral obstruction may include ureterotomy, ureteroneocystostomy, ureteronephrectomy, ureteral stent, subcutaneous ureteral bypass, nephrostomy tube, and renal transplantation. At this time, ureteral obstructions in dogs are not as common.
Clinical signs of a ureteral obstruction will likely be non-specific and may include anorexia, vomiting, polyuria, polydipsia, stranguria, and pollakiuria. Diagnosis is usually obtained via a combination of radiographs, ultrasound and possibly computerized tomography. Medical treatment is only successful in approximately 8–17% of the patients; therefore we prefer surgery if possible, especially if medical therapy fails.
Traditional surgery alone (ureterotomy, ureteroneocystostomy, etc.) may result in a recurrence rate of 40%. Subsequently, many surgeons have augmented their surgical approach by placing ureteral stents or performing a subcutaneous ureteral bypass procedure. These procedures have the theoretical benefit that additional ureteroliths will be unable to form and cause an obstruction. The perioperative mortality rate for ureteral surgery is variable (18–39%) and likely dependent on many surrounding factors. The complication rate is approximately 20–25%, but more recently has been reported to be as low as 7.5% with the use of stents. The most common complications encountered requiring a revision surgery are urine leakage and stenosis at the surgical site.
There are no obvious factors that can be analyzed to determine which patients are ideal candidates for surgery. In general those with a higher presenting BUN, higher creatinine at discharge, and fluid overloading while hospitalized will have a decreased overall survival. Although these cases can be time consuming, difficult, and expensive, the majority of patients do well and ultimately have a good quality of life. Despite their complexity, if owners are committed, we recommend treatment. It is important that both owners and veterinarians are fully aware of the potential treatment paths, pitfalls, setbacks, and pros of ureteral surgery.
Advanced microvascular surgical training and the availability of an operating microscope are strongly recommended to help increase the chances of surgical success.