Acute on chronic kidney disease in dogs: Etiology, clinical and clinicopathologic findings, prognostic markers, and survival

Background: Chronic kidney disease (CKD) and acute exacerbation of CKD (ACKD) are common in dogs. Objective: To characterize the etiology, clinical and laboratory findings, and short- and long-term prognosis of dogs with ACKD. Animals: One hundred dogs with ACKD. Methods: Medical records of dogs diagnosed with ACKD admitted to a veterinary teaching hospital were retrospectively reviewed. Results: The most common clinical signs included anorexia (84%), lethargy (77%), vomiting (55%) and diarrhea (37%). Presumptive etiology included inflammatory causes (30%), pyelonephritis (15%), ischemic causes (7%), other (3%), or unknown (45%). Median hospitalization time was 5 days (range, 2-29 days) and was significantly longer in survivors (6 days; range, 2-29 days) compared with nonsurvivors (4 days; range, 2-20 days; P <.001). Mortality rate was 35%. International Renal Interest Society (IRIS) acute kidney injury (AKI) grade at presentation was associated (P =.009) with short-term survival, but presumptive etiology was not (P =.46). On multivariable analysis; respiratory rate (P =.01), creatine kinase (CK) activity (P =.005) and serum creatinine concentration (SCR; P =.04) at presentation were associated with short-term outcome. Median survival time of dogs discharged was 105 days (95% confidence interval [CI], 25-184), with 35 and 8 dogs surviving up to 6 and 12 months, respectively. Presumptive etiology (P =.16) and SCR (P =.59) at discharge were not predictors of long-term survival. Conclusion and Clinical Importance: Short-term outcome of dogs with ACKD is comparable to those with AKI but long-term prognosis is guarded. The IRIS AKI grade at presentation is a prognostic indicator of short-term outcome.