Progression of Chronic Kidney Disease in Cats After Subcutaneous Ureteral Bypass Placement Compared to Cats With Idiopathic Chronic Kidney Disease

Background

Chronic kidney disease (CKD) is a common sequela of ureteral obstruction, but many cats are non-azotemic after subcutaneous ureteral bypass (SUB) placement.

Objectives

Compare CKD progression rates after SUB placement with idiopathic CKD (iCKD), and explore variables associated with progression.

Animals

Seventy-one referred cats after SUB placement for ureteral obstruction and 89 primary care cats with iCKD.

Methods

Retrospective observational longitudinal study. Baseline (3–6 months after SUB or at CKD diagnosis for iCKD cases) clinicopathological data and CKD progression (≥ 25% increase in creatinine concentration [Cr]) rates were compared between iCKD and SUB cats. Univariable logistic regression identified variables associated with SUB cat CKD progression.

Results

Baseline Cr was lower in the SUB group (SUB, 2.0 mg/dL; iCKD, 2.3 mg/dL; p = 0.01). For SUB cats with a ≥ 25% increase in Cr within 1 year, 45% (9/20) had SUB obstruction. Of the remaining 11 cats, 35% had a positive urine culture. Only SUB blockage was associated with CKD progression in SUB cats (odds ratio, 33.33; confidence interval [CI], 3.80–292.60; p = 0.002). Progression of CKD within 1 year did not differ between groups (iCKD, 29.5%; SUB, 28.1%; p = 0.85), even after exclusion of obstructed cases (iCKD, 29.5%; SUB, 17.7%; p = 0.12). Median time to CKD progression was not different between groups (iCKD, 833 days; range, 21–2141; SUB, 653 days; range, 43–1662; p = 0.80).

Conclusions and Clinical Importance

Progression of CKD after SUB placement occurs with similar frequency and time frame as in cats with iCKD, but should prompt assessment for SUB blockage and pyelonephritis.