Changes

==Introduction==

==Introduction==

This section only covers the intrinsic causes or ARF, as pre- and post-renal failure are very different disease processes.  

This section only covers the intrinsic causes or ARF, as pre- and post-renal failure are very different disease processes.  

'''[[Toxicology|Toxic injury]]''' is the most common cause. Drugs such as '''aminoglycosides, fluroquinolones, amphotericine , [[NSAIDs|NSAIDs]],  and ACE-inhibitors''' are known to cause acute renal failure.  [[Ethylene Glycol Toxicity|Ethylene glycol]], [[House Plant Toxicity|easter lillies]], Hemotoxic snake venoms etc. contribute to toxic ARF. However, the access to different kinds of toxins varies as per geographic distribution. Some toxic agents act directly on tubular cells, some act on the haemodynamics of the kidney, whilst others cause damage by precipitating within the tubules.  

'''[[Toxicology|Toxic injury]]''' is the most common cause. Drugs such as '''aminoglycosides, fluroquinolones, amphotericine , [[NSAIDs|NSAIDs]],  and ACE-inhibitors''' are known to cause acute renal failure, if used unjudiciously.  [[Ethylene Glycol Toxicity|Ethylene glycol]], [[House Plant Toxicity|easter lillies]], hemotoxic snake venoms etc. contribute to toxic ARF. However, the access to different kinds of toxins varies as per geographic distribution. Some toxic agents act directly on tubular cells, some act on the haemodynamics of the kidney, whilst others cause damage by precipitating within the tubules.  

'''[[Ischaemia|Ischaemic injury]]''' is also common, especially following hospitalisation. It is therefore essential to monitor the fluid therapy requirements of hospital patients, especially peri- and post-operatively to prevent pre-renal [[Azotaemia|azotaemia]] and subsequent ischaemia.  

'''[[Ischaemia|Ischaemic injury]]''' is also common, especially following hospitalisation. It is therefore essential to monitor the fluid therapy requirements of hospital patients, especially peri- and post-operatively to prevent pre-renal [[Azotaemia|azotaemia]] and subsequent ischaemia.  

* '''Malaise'''

* '''Malaise'''

* '''[[Vomiting|Vomiting]]'''

* '''[[Vomiting|Vomiting]]'''

There may also be evidence of swollen or painful kidneys on abdominal palpation, an increased or decreased heart rate, hypothermia and oral ulceration or signs of a concurrent disease.  

There may also be evidence of swollen or painful kidneys on abdominal palpation, an increased or decreased heart rate, hypothermia and oral ulceration or signs of a concurrent disease.  

The most suggestive sign of severe acute renal failure is '''oliguria or anuria'''. It does not occur in all cases so should not be completely relied on for diagnosis. Bloodwork should show [[azotaemia]].  

The most suggestive sign of severe acute renal failure is '''oliguria or anuria'''. It does not occur in all cases so should not be completely relied on for diagnosis. Bloodwork should show [[azotaemia]].

==Diagnosis==

==Diagnosis==

The aim of treatment is to '''support the patient whilst the tubules repair'''. If the ingestion of a specific toxin is known then further exposure should be prevented and  an '''antidote''' may be given if available (for example ethanol in [[Ethylene Glycol Toxicity|ethylene glycol toxicity]]). More commonly, by the time of presentation the damage to the kidneys has already occurred and it is no longer appropriate to administer the antidote. If any other underlying cause has been identified (such as [[Pyelonephritis|pyelonephritis]]), this should be treated appropriately.

The aim of treatment is to '''support the patient whilst the tubules repair'''. If the ingestion of a specific toxin is known then further exposure should be prevented and  an '''antidote''' may be given if available (for example ethanol in [[Ethylene Glycol Toxicity|ethylene glycol toxicity]]). More commonly, by the time of presentation the damage to the kidneys has already occurred and it is no longer appropriate to administer the antidote. If any other underlying cause has been identified (such as [[Pyelonephritis|pyelonephritis]]), this should be treated appropriately.

'''Aggressive [[Fluid therapy|fluid therapy]] is the mainstay of treatment in ARF cases'''. A mild level of volume overload is ideal as it promotes urine production, however as animals are often oliguric, care should be taken not to overload the body with too much fluid. In addition [[Diuretics Effects on Kidneys - Anatomy & Physiology|'''diuretics''']] such '''frusemide and mannitol''' can be administered to stimulate urine production. A '''closed collection system''' should be used to '''monitor urine output'''.  

'''Aggressive [[Fluid therapy|fluid therapy]] is the mainstay of treatment in ARF cases'''. A mild level of volume overload is ideal as it promotes urine production, however as animals are often oliguric, care should be taken not to overload the body with too much fluid. In addition [[Diuretics Effects on Kidneys - Anatomy & Physiology|'''diuretics''']] such as '''frusemide and mannitol''' can be administered to stimulate urine production. A '''closed collection system''' should be used to '''monitor urine output'''.  

Severe '''metabolic disturbances''' occur secondary to ARF. '''Hyperkalaemia''' is a common occurrence and is also treated with '''fluid therapy''' using a product such as saline. If it is severe and compromising the cardiac function of the animal then '''calcium gluconate''' can be administered to stabilise the heart (whilst levels are reduced by fluid therapy).  

Severe '''metabolic disturbances''' occur secondary to ARF. '''Hyperkalaemia''' is a common occurrence and is also treated with '''fluid therapy''' using a product such as saline. If it is severe and compromising the cardiac function of the animal then '''calcium gluconate''' can be administered to stabilise the heart (whilst levels are reduced by fluid therapy).  

If this treatment is not sufficient to maintain the animal then a method of '''dialysis''' may be considered.

If this treatment is not sufficient to maintain the animal then a method of '''dialysis''' may be considered.

:'''Peritoneal Dialysis:''' This technique uses the omentum within the peritoneum as a filter to remove uraemic toxins. It is used in specialist referral centres when it is considered likely that the cat may recover from ARF. The technique is labour intensive but well tolerated by the animal.  

<br>'''Peritoneal Dialysis:''' This technique uses the omentum within the peritoneum as a filter to remove uraemic toxins. It is used in specialist referral centres when it is considered likely that the cat may recover from ARF. The technique is labour intensive but well tolerated by the animal.  

:'''Hemodialysis:''' This is rarely performed due to the high cost of equipment and ethical questions surrounding longterm treatment. It is only available at a limited number of specialist hospitals.

<br>'''Hemodialysis:''' This is rarely performed due to the high cost of equipment and ethical questions surrounding longterm treatment. It is only available at a limited number of specialist hospitals. However, the technical advances and increased experience with the clinical applications of hemodialysis is changing the face of therapeutic options available for acute renal failure patients worldwide. If applied early in the course of acute renal insult, hemodialysis can significantly reduce mortality and/or progression towards chronic renal parenchymal changes.

 

==Prognosis==

==Prognosis==

Prognosis is entirely dependant on whether the animal can be supported whilst the tubules repair. Often intensive care for prolonged peroids (up to eight weeks) is required to achieve this. Generally, animals presenting with '''oliguria''', particularly with a history of toxin ingestion have a '''grave prognosis'''. Renal biopsy may give an indication of the reversibility of the condition (if the basement membrane is intact) and therefore prognosis - it should be considered prior to starting dialysis. If urine production is not restored following treatment, prognosis is very poor and euthanasia may be the only appropriate option.  

Prognosis is entirely dependant on whether the animal can be supported whilst the tubules repair. Often intensive care for prolonged peroids (up to eight weeks) is required to achieve this. Generally, animals presenting with '''oliguria''', particularly with a history of toxin ingestion have a '''grave prognosis'''. Renal biopsy may give an indication of the reversibility of the condition (if the basement membrane is intact) and therefore prognosis - it should be considered prior to starting dialysis. If urine production is not restored following treatment, prognosis is very poor and euthanasia may be the only appropriate option.  

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[[Category:Renal Failure]]

[[Category:Renal Failure]]

[[Category:Expert Review - Small Animal]]

[[Category:Expert Review - Small Animal]]