NAVLE Urinary

Canine Acute Kidney Injury Study Guide

March 28, 2026 25 min read 27 views
Acute Kidney Injury (AKI) refers to the sudden onset of renal parenchymal damage with or without recognizable loss of function.

Overview and Clinical Importance

Acute Kidney Injury (AKI) refers to the sudden onset of renal parenchymal damage with or without recognizable loss of function. AKI represents a spectrum ranging from mild, clinically inapparent nephron injury to severe, life-threatening failure of the kidneys to meet excretory, metabolic, and endocrine demands. The mortality rate remains high (45-60%) even with aggressive treatment, making early recognition and intervention critical for patient survival.

AKI differs fundamentally from chronic kidney disease (CKD) in its potential reversibility. While CKD represents irreversible structural damage, AKI may resolve completely with appropriate treatment if the underlying cause is addressed before permanent nephron loss occurs. However, surviving dogs may develop residual CKD, emphasizing the importance of long-term monitoring.

High-YieldOn the NAVLE, remember the key differentiating features between AKI and CKD: AKI presents with acute onset in a previously healthy animal, normal body condition, enlarged painful kidneys on palpation, and no history of PU/PD. CKD shows chronic weight loss, small irregular kidneys, and a history of progressive illness.
Phase Characteristics and Clinical Significance
1. Initiation Occurs during and immediately after insult. Pathologic damage is initiated but clinical signs may not be apparent. Biochemistry usually normal. Best time for intervention.
2. Extension Continued ischemia, hypoxia, inflammation, and cellular injury. Leads to cellular apoptosis and necrosis. Laboratory abnormalities begin to appear.
3. Maintenance Critical damage has occurred. Characterized by azotemia and uremia lasting days to weeks. Oliguria (less than 0.5 mL/kg/hr) or anuria may occur. Highest morbidity/mortality risk.
4. Recovery Azotemia improves; renal tubules undergo repair. Marked polyuria may occur due to partial tubular function restoration and osmotic diuresis. Can take weeks to months.

Pathophysiology of AKI

Four Phases of AKI

Understanding the phases of AKI is essential for appropriate timing of intervention and prognostication:

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