Acute on Chronic Kidney Disease in Dogs: Prognosis & Survival

In the Literature

Dunaevich A, Chen H, Musseri D, et al. Acute on chronic kidney disease in dogs: Etiology, clinical and clinicopathologic findings, prognostic markers, and survival. J Vet Intern Med. 2020;34(6):2507-2515.

The Research …

Chronic kidney disease (CKD) is common in dogs and often detected late in the course of disease when the patient is no longer able to compensate for declining kidney function. Canine acute kidney injury (AKI) is also a common clinical finding, usually secondary to ischemia, infection, toxicity, or systemic inflammation. Determining whether signs of kidney disease are acute, chronic, or acute on chronic (ACKD) can be difficult. 

In this study, medical records of 100 dogs were retrospectively analyzed to characterize the causes, clinical signs, laboratory results, and short- and long-term prognoses associated with diagnosis of ACKD. The most common causes of ACKD were unknown (45%), inflammatory (30%), pyelonephritis (15%), ischemic (7%), and other (3%). The underlying cause of ACKD was not related to survival. The median length of hospitalization was 5 days overall and 6 days for surviving dogs (vs 4 days for nonsurviving dogs).

Sixty-five dogs (65%) survived to discharge, and 35 died (35%); this survival rate is higher than the mortality rate of 53% to 62% previously associated with AKI.^1-3 Median survival time was 105 days for the 61 surviving dogs for which follow-up information was available, with 35 (57%) dogs surviving 6 months and 8 (13%) dogs surviving one year. This was lower than the one-year survival rate (33%) of dogs with severe AKI treated with hemodialysis.² This discrepancy is likely due to the presumed normal renal function of dogs with AKI prior to injury, as dogs with ACKD have pre-existing kidney damage and thus reduced renal reserve. 

The long-term survival rate of dogs with CKD is highly variable and associated with the International Renal Interest Society (IRIS) CKD stage.⁴ IRIS grade of AKI (see Suggested Reading), respiratory rate, creatine kinase activity, and serum creatinine concentration at presentation were all associated with short-term outcome in dogs with ACKD.

… The Takeaways

Key pearls to put into practice:

• Patients with CKD may develop an acute worsening of renal disease. In these cases, the presenting IRIS AKI grade, respiratory rate, creatine kinase activity, and serum creatinine concentration may be associated with short-term outcome.

• ACKD is a common clinical scenario in dogs and is often secondary to inflammatory conditions (eg, pancreatitis, infection). The underlying cause of acute deterioration in kidney function does not seem to be associated with survival.

• Short-term prognosis in dogs with ACKD is similar to patients with AKI, and pet owners should expect their pet to be hospitalized for several days. Long-term prognosis for patients with ACKD is guarded.