Changes

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

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

==Diagnosis==

==Diagnosis==

* '''Whether the renal failure is pre-renal, renal or post-renal'''

* '''Whether the renal failure is pre-renal, renal or post-renal'''

As mentioned it is important to differentiate ARF from decomensated [[Chronic Renal Failure|CRF]], as '''ARF''' is potentially '''reversible with aggressive therapy'''. The only diagnostic test that can achieve this is '''biopsy''', but due to the high level of risk involved in an already sick animal this is normally not performed. Instead the following factors can be used by the clinician to guide diagnosis:

As mentioned it is important to differentiate ARF from decomensated [[Chronic Renal Failure|CRF]], as '''ARF''' is potentially '''reversible with aggressive therapy'''. The only diagnostic test that can achieve this is '''biopsy''', but due to the high level of risk involved in an already sick animal this is normally not performed. Instead the following factors can be used by the clinician to guide diagnosis:

'''(2) Renal'''

'''(2) Renal'''

This is caused by a '''direct insult to the kidney''', with intrinsic damage. In these cases azotaemia is present, and urine specific gravity is between 1.007 and 1.025. There may be evident of inflammation in the urine sediment and a high sodium content. There is only a '''minimal response to fluid therapy'''. The hallmark of primary renal failure is azotaemia in the presence of poorly concentrated urine.

This is caused by a '''direct insult to the kidney''', with intrinsic damage. In these cases azotaemia is present, and urine specific gravity is between 1.007 and 1.025. There may be evident of inflammation in the urine sediment and a high sodium content. There is only a '''minimal response to fluid therapy'''. The hallmark of primary renal failure is '''azotaemia''' in the presence of '''poorly concentrated urine'''.

'''(3) Post-renal'''

'''(3) Post-renal'''

==Treatment==

==Treatment==

The aim of treatment is to '''support the patient whilst the tubules repair'''. If the ingestion of a specific toxin is known then 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 '''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). '''Metabolic acidosis''' also occurs, and again can be treated with '''fluid therapy'''. A fluid such as '''Hartmanns''' which contains '''bicarbonate''' should be used. If this is insufficient to resolve the acidosis then bicarbonate can be administered directly.

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). '''Metabolic acidosis''' [[File:Hemodialysismachine.jpg|thumb|100px|right|'''Hemodialysis machine''' (Wikimedia Commons)]]  also occurs, and again can be treated with '''fluid therapy'''. A fluid such as '''Hartmanns''' which contains '''bicarbonate''' should be used. If this is insufficient to resolve the acidosis then bicarbonate can be administered directly. The use of dopamine in dogs to cause renal vasodilation can be used but its currently not recommended.  

Additional supportive treatment includes '''anti-emetic drugs''' and [[Gastroprotective Drugs|'''gastro-protectants''']] such as sucralfate and ranitidine. A low protein diet can be fed to reduce the levels of uraemic toxins and an oesophageal tube should be placed in any anorexic animals.  

Additional supportive treatment includes '''anti-emetic drugs''' and [[Gastroprotective Drugs|'''gastro-protectants''']] such as sucralfate and ranitidine. A low protein diet can be fed to reduce the levels of uraemic toxins and an oesophageal tube should be placed in any anorexic animals.  

'''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.  

'''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.  

'''Haemodialysis:''' 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.   

'''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.   

   

   

==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 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.  

==References==

==References==

Gleadhill, A (1994) '''Differential diagnosis of renal failure in the dog''' ''In Practice 1994 16: 216-22''

Gleadhill, A (1994) '''Differential diagnosis of renal failure in the dog''' ''In Practice 1994 16: 216-22''

RVC staff (2009) '''Urogenital system''' RVC Intergrated BVetMed Course, ''Royal Veterinary College''

RVC staff (2009) '''Urogenital system''' RVC Intergrated BVetMed Course, ''Royal Veterinary College''

[[Category:To Do - Urinary]]

[[Category:To Do - Urinary]]

[[Category: To Do - Siobhan Brade]]

[[Category: To Do - Siobhan Brade]]