AKI and acute renal failure

Question 1

When do acute kidney injuries occur most commonly in horses?

Answer 1

During hospitalisation

Question 2

What is acute renal failure?

Answer 2

• Advanced decline in glomerular filtration rate (GFR)
• Over hours – days
• Clinical signs and clinical pathology associated with marked decrease in GFR

Question 3

What causes ARF?

Answer 3

• Haemodynamic
• Nephrotoxic
• Uncommon
  
  • Interstitial nephritis
  • Obstructive nephropathy (discussed in pigmenturia)
• Rare
  
  • Acute glomerulopathies - (Immune mediated most commonly)

Question 4

What is involved in haemodynamic ARF?

Answer 4

• Any condition that causes sustained marked hypotension
• Also called vasomotor or sepsis-associated
• Predisposing systemic inflammatory disorder (colitis, surgical colics)
• Hypotension and DIC frequently associated
• Risk Factors
  
  • Enterocolitis
  • Haemorrhagic shock
  • Severe intravascular volume deficits
  • Septic shock
  • Coagulopathy

Question 5

What can cause nepthotoxic ARF?

Answer 5

• Antibiotics - dehydrated or hypotensive most at risk (aminoglycosides and oxytet)
• NSAIDs
• Myopathy and Haemolysis
• Vitamin D or K3
• Heavy Metals

Question 6

What can cause interstitial nephritis?

Answer 6

• Allergic reaction - Beta lactams, TMPS
• Immune mediated
• Ascending infection

Question 7

What clinical signs are associated with AKI/ARF?

Answer 7

• Predisposing disease
  
  • D+
  • SIRS/MODS
  • Myopathies
• Colic
• Fever?
  
  • More from primary disease
• Urine output
  
  • Oliguria, anuria, polyuria

Question 8

What typical clinical pathology results would you get with ARF?

Answer 8

**Creatinine ** (SDMA up and coming)
* Increased
* Severity dependant on disease process
* Pre-renal component too?

USG
* 1.008-1.016 (often, not the rule)
* >1.025
* Often pre-renal
* Pre renal + ARF
* Often the case - Difficult to interpret

Urine Dipstick
* +/-proteinuria
* Glomerular disease?
* +/-Haeme

Serum Electrolytes
* Hyponatraemia
* Hypochloraemia
* Potassium
* Variable
* More so hyperkalaemic
* Esp oliguric or anuric
* Can be life threatening

Question 9

What could you see on transabdominal ultrasound that would suggest ARF/AKI?

Answer 9

May see
* Enlarged kidneys
* Increased corticomedullary definition
* Perirenal oedema
* Enlarged cortex

Question 10

Why would you undertake a renal biopsy in an ARF/AKI case?

Answer 10

Useful if
* Unsure of aetiology
* Prognosticator

Won’t change the treatment in the majority of cases

Question 11

How is AKI/ARF treated?

Answer 11

• Stop nephrotoxic drugs
• Manage primary disease
• IVFT (intravenous fluid therapy)
  
  • Hartmanns
    
    • Gentle, no need to bolus
    • At least 2-4 days
• Complicated when oliguric or anuric ARF

Question 12

What is the prognosis of the different types of ARF?

Answer 12

**Haemodynamic **
Can we treat the primary disease?
Can we improve perfusion?

Nephrotoxic
Amount of urine produced
Improvement in serum creatinine

Oliguric and anuric
Poor to guarded
If converts to polyuria, better