Acute kidney injury (AKI) in dogs and cats is diagnosed by identifying acute renal parenchymal injury with or without azotemia, and managed through cause elimination, fluid optimization, complication control, and renal replacement therapy when conventional management fails.

Diagnosis

AKI is defined as sudden renal parenchymal damage developing within approximately 48 hours, distinguished from chronic kidney disease (CKD) by the acuity of onset and, on ultrasound, by increased rather than decreased renal size and cortical thickness.The Veterinary…+1 During AKI, inflammation causes edema and increased cortical thickness, whereas CKD is associated with cortical thinning and reduced kidney length.Veterinary Radi… This ultrasonographic distinction is clinically useful when historical baseline creatinine values are unavailable.

The minimum diagnostic database includes serum creatinine, urea, phosphorus, electrolytes, acid-base status, urinalysis with urine specific gravity, and urine culture by cystocentesis.The Veterinary…+1 Biochemical markers of AKI — elevated creatinine, elevated urea, and proteinuria — appear 24 to 48 hours after a nephrotoxic or ischemic insult.Journal of Smal… A presumptive diagnosis of acute pyelonephritis (APN) as the cause of AKI is made when urine culture collected by cystocentesis is positive.MSD Vet Manuals+1

Neutrophil gelatinase-associated lipocalin (NGAL) is an early damage biomarker that rises in urine and blood within hours of tubular injury, enabling detection of non-azotemic or International Renal Interest Society (IRIS) grade 1 AKI before creatinine increases.Journal of Vete… NGAL concentrations also correlate with the healing process and have been explored as a predictor of recovery.Journal of Vete…

Serum fibroblast growth factor-23 (FGF-23) is elevated in dogs and cats with AKI. In dogs, median serum FGF-23 is 2104.0 pg/mL in AKI versus 278.5 pg/mL in controls, and in cats, 1195 pg/mL versus 138 pg/mL in controls.The Veterinary… In dogs, serum FGF-23 correlates positively with serum creatinine (r = 0.67) and phosphate (r = 0.893).The Veterinary… Dogs with AKI also have significantly higher serum magnesium (median 2.65 mg/dL) compared to controls (median 2.0 mg/dL).The Veterinary…

Systemic hypertension (SH) is present in 81% to 87% of dogs with AKI based on retrospective data, making blood pressure measurement an essential component of the initial assessment.Journal of Vete… In cats with AKI, the presence of SH does not affect survival, whereas in dogs, SH is associated with significantly reduced glomerular filtration rate.Journal of Vete…

Differentiating AKI from acute-on-chronic kidney disease (ACKD) is clinically challenging, as the pathogenesis, clinical presentation, and laboratory abnormalities of ACKD can closely resemble those of AKI.Journal of Vete… Evidence of pre-existing CKD — prior azotemia, small kidneys, or renal secondary hyperparathyroidism — supports ACKD over de novo AKI.

Management

Treatment is directed at eliminating the underlying cause, correcting fluid and electrolyte derangements, preventing and treating complications including hypertension, and providing supportive care until renal recovery occurs.Journal of Vete…

For Vitis fruit (grape, raisin, currant, sultana) ingestion in dogs, aggressive decontamination is recommended regardless of ingested amount, including emesis, gastric lavage, and activated charcoal after recent ingestion, followed by intravenous fluid diuresis for at least 48 hours.Journal of Smal… Serum chemistry should be monitored for 72 hours post-ingestion for AKI development.Journal of Smal… Emesis is effective at removing grapes from the stomach and can be effective many hours post-ingestion.Journal of Smal… Approximately 15% of dogs and cats will develop clinical signs after Vitis fruit ingestion, predominantly gastrointestinal, with a very limited number developing symptomatic AKI when proper decontamination is applied.Journal of Smal… In cats, the evidence supporting emesis induction and prophylactic intravenous fluid therapy for AKI prevention after Vitis fruit ingestion is insufficient to make a firm recommendation.Journal of Smal…

For APN as a cause of AKI, empirical antibiotic therapy should be started while urine culture and susceptibility results are pending, as results typically require several days.Journal of the… In cats, Escherichia coli resistant to potentiated penicillins is a frequent causative organism, which should inform empirical antibiotic selection.Journal of the… Quantitative urine culture and susceptibility testing remain the standard of care to guide definitive therapy.Journal of the…

Fluid therapy is the cornerstone of AKI management, directed at correcting hypovolemia and dehydration while avoiding fluid overload.Journal of Smal…+1 Urine output must be monitored closely, as AKI can present with polyuria, oliguria, or anuria.Journal of Smal…

Renal replacement therapy (RRT) is indicated when conventional management is insufficient to control uremic toxin accumulation, fluid imbalance, or electrolyte abnormalities.Journal of the… Modalities include continuous renal replacement therapy (CRRT), intermittent hemodialysis (IHD), and peritoneal dialysis.Journal of the… IHD removes solutes primarily by diffusion and excess fluid by ultrafiltration over 4 to 5 hours but is available only at specialty centers with dedicated equipment and expertise.Journal of the… CRRT is a safe and effective initial modality for dogs with AKI.Journal of the…

Overall mortality of dogs and cats with AKI is approximately 50%.Journal of Vete… Community-acquired AKI in dogs carries a mortality of 34% to 45%, while hospital-acquired AKI carries a mortality of 44% to 86%.Journal of Vete… APN as a cause of AKI in cats carries a better prognosis than other AKI etiologies.Journal of the…

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