Use of the subcutaneous ureteral bypass device and urethral stenting for treatment of malignant urinary outflow tract obstructions in cats.

Objectives: The aim of this study was to describe the technical success and outcomes of ureteral and urethral decompression using the subcutaneous ureteral bypass (SUB) device and transurethral self-expanding metallic stents (SEMS) as a palliative treatment option for feline malignant urinary outflow tract obstructions.
Methods: A retrospective study was conducted of 14 cats with ureteral and/or urethral obstructions secondary to diagnosed or suspected transitional cell carcinoma (TCC). In all cats, a SUB device and/or a SEMS was placed to relieve the obstruction(s). Group 1 consisted of cats with ureteral obstructions, with or without concurrent urethral obstructions, and group 2 consisted of cats with only urethral obstructions.
Results: Eight cats were included in group 1 (seven with concurrent urethral obstructions) and six cats were included in group 2. TCC was confirmed in 8/14 cats. Repeat urethral obstruction due to tumor in growth occurred in 6/13 (46%) cats with a SEMS, and no cats developed recurrent ureteral obstructions after placement of the SUB device. Three cats had additional covered stents placed after urethral re-obstruction. The median survival time (MST) from the time of device placement was 52 days in group 1 (mean 92; range 14-349) and 80 days in group 2 (mean 96; range 7-209). The MST from the time of mass identification of the cats that did and did not receive adjunctive therapy was 349 days (mean 358; range 124-602) and 43 days (mean 113; range 14-423), respectively.
Conclusions and Relevance: The use of bypass devices for feline malignant urinary outflow tract obstructions is a viable option to provide immediate renal and urinary bladder decompression. TCC in cats is locally aggressive and can result in urethral re-obstruction, prompting consideration for placing a covered urethral stent. The use of adjunctive therapies for malignant neoplasia should be considered to improve overall survival once the obstruction has been relieved.
Competing Interests: Conflict of interestAllyson Berent and Chick Weisse are consultants for Norfolk Vet and Infiniti Medical, which are the companies that supply the SUB device and urethral stents for veterinary patients.