Dogs and cats with acute-on-chronic kidney disease have worse outcomes than those with acute kidney injury following renal replacement therapy.

OBJECTIVE

To compare survival to discharge and long-term outcomes in dogs and cats with acute-on-chronic kidney disease (ACKD) compared to acute kidney injury (AKI) treated with renal replacement therapy (RRT) and to identify factors associated with outcome.

DESIGN

Retrospective observational design.

SETTING

Single referral hospital.

ANIMALS: 136 client-owned animals (67 dogs and 69 cats) treated with RRT between 2017 and 2024.

MEASUREMENTS AND MAIN

RESULTS

This retrospective observational cohort study reviewed medical records from a referral hospital. Animals were classified as having ACKD (n = 66) or AKI (n = 70). Short-term survival was evaluated as survival to discharge, restricted mean survival time (RMST) and logistic regression models. Long-term survival was assessed using Kaplan-Meier analysis, RMST and Cox proportional hazards models. Animals with ACKD were older than those with AKI (10.4 ± 3.9 years vs. 6.3 ± 3.3 years; p < 0.0001) and had higher serum creatinine concentrations at discharge (3.38 ± 1.16 mg/dL vs. 2.81 ± 2.92 mg/dL; adjusted p = 0.0073). Survival to discharge was 53% (35/66) for ACKD and 70% (49/70) for AKI. Short-term survival did not differ significantly between groups (log-rank p = 0.089). Among animals survived to discharge, RMST was shorter for ACKD. Median survival time for the ACKD group was 57 days overall and 33 days for dogs.

CONCLUSION

Although statistically significant differences were not identified, dogs and cats with ACKD had lower survival to discharge and numerically shorter long-term survival than animals with AKI. Nevertheless, 53% of RRT-treated animals with ACKD survived to discharge, demonstrating that short-term survival is achievable in selected ACKD patients.