Acute kidney injury (Canine) — NAVLE Prep

Quick anchor

Trigger

Acute azotemia, oliguria/anuria, or toxin / ischemia history

First step

Stabilize perfusion and rule out postrenal obstruction

Think

Prerenal vs intrinsic renal vs postrenal

Trap

Azotemia alone does not prove intrinsic renal failure

Exam core — read this first

Board frame → localize acute azotemia before committing to a prognosis

Immediate priorities → volume status, potassium, urine output, and obstruction check

Major causes → toxic, ischemic, infectious, and postrenal processes

NAVLE logic → postrenal and prerenal causes can mimic renal azotemia early

Pattern recognition

Core pattern

Acute onset illnessAzotemiaUrine output change or toxin / ischemia history

Supporting clues

VomitingDehydration or shockHyperkalemia if postrenal/oliguricLarge painful bladder if obstructedRenal pain or fever if infectious

NAVLE trigger: The high-yield move is to localize the azotemia and decide whether the problem is reversible with fluids or decompression.

Decision core — what NAVLE actually asks

Poor perfusion / dehydration

→ Correct circulating volume first, then reassess renal values and urine output

Distended bladder or no urine output

→ Treat as postrenal until obstruction or rupture is excluded

Toxin, infection, or persistent azotemia after rehydration

→ Intrinsic AKI rises higher and needs targeted diagnostics plus monitoring

Key interpretation

Urine output

Critical

Oliguria/anuria changes urgency and prognosis

Potassium

May be high

Especially with postrenal disease or severe oliguria

Perfusion status

Reassess

Values can improve if azotemia was prerenal

Bladder size

Very useful

Large bladder pushes obstruction up the list

Urinalysis

Context dependent

Helps with concentration and inflammatory clues

Trend

More useful than one value

Serial values beat a single chemistry panel

⚠ Acute azotemia is not automatically intrinsic renal failure. Rehydration and obstruction assessment can completely change the case.

Treatment

Step 1

Restore perfusion, address shock, and stabilize dangerous electrolyte abnormalities

The patient dies from instability before the diagnosis gets pretty.

Step 2

Relieve obstruction or manage the underlying cause if postrenal or toxin/infectious AKI is identified

Localization drives the next move.

Step 3

Monitor urine output, renal values, and hydration carefully

AKI management is a trending game, not a one-time decision.

NAVLE traps — where students lose marks

Do not call all azotemia “renal failure” on first presentation

Prerenal and postrenal disease may be more reversible and need different first steps.

A blocked patient can look “renal” on chemistry

Postrenal azotemia is one of the classic exam traps.

Do not flood an oliguric patient blindly without reassessment

Volume status and urine output still matter after initial stabilization.

Intrinsic AKI still needs a cause search

Toxins, leptospirosis, pyelonephritis, and ischemia are not interchangeable.

Differentials — how to separate these on NAVLE

Fast separator: Acute kidney injury questions usually ask you to sort prerenal, intrinsic renal, and postrenal disease before naming a final diagnosis.

Category	Typical clue	Urine output/bladder	Board separator
Prerenal azotemia	Dehydration / shock history	Bladder not distended	Improves after perfusion is restored
Intrinsic AKI	Toxin, infection, ischemia, persistent azotemia	Variable output	Does not simply correct with fluids
Postrenal azotemia	Stranguria, anuria, leakage, obstruction	Often distended bladder if obstructed	Decompression changes the case
Chronic kidney disease	Longer history, weight loss, PU/PD	Usually not acute obstructed crisis	Chronicity clues and trends matter

30-second revision

LocalizePrerenal vs intrinsic renal vs postrenal

Check firstPerfusion, potassium, urine output, bladder

Postrenal clueDistended bladder / obstruction signs

Intrinsic cluePersists after rehydration or fits toxin/infection

TrapAzotemia alone is not enough

Practice questions

Pre-built NAVLE-style · Acute kidney injury

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Q1Localization

Which finding most strongly pushes an azotemic dog toward postrenal rather than intrinsic renal disease?

Q2Reassessment

Why is rehydration followed by repeat assessment high yield in azotemic dogs?

Q3Urgency

Which feature makes an azotemic dog an immediate stabilization problem rather than a routine outpatient renal workup?

Q4Cause pattern

A dog remains azotemic after rehydration and has a known ethylene glycol exposure. Which category is most appropriate?

Q5Trap question

Which statement about canine acute kidney injury is most accurate?