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− | ==Description== | + | ==Introduction== |
− | Hepatic encephalopathy is neurological disfunction caused by any acute or severe hepatic insult; 60-80% of hepatic function must be lost before clinical signs develop. A combination of mechanisms is probably responsible for the syndrome. | + | '''Hepatic encephalopathy''' is neurological dysfunction caused by any acute or severe hepatic damage; 60-80% of hepatic function must be lost before clinical signs develop. |
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| + | The cause of hepatic encephalopathy is hepatic insufficiency; the pathophysiology causing the neurological dysfunction is probably multifactorial. The following mechanisms have been suggested: accumulation of gastro-intestinal derived neurotoxins, imbalance of inhibitory and excitatory neurotransmitters, disruption of CNS energy metabolism, and the development of false neurotransmitters. |
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| ==Signalment== | | ==Signalment== |
− | No age, sex or breed predisposions. | + | No age, sex or breed predispositions. |
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− | There are many hepatic disorders which can lead to hepatic encephalopathy including, [[Hepatitis, Equine Serum|Hepatitis]], [[Ragwort Toxicity]], [[Tyzzer's Disease]] and [[Hyperlipaemia - Horse|Hyperlipaemia]] | + | There are many hepatic disorders which can lead to hepatic encephalopathy including, '''Hepatitis, [[Ragwort Toxicity]], [[Tyzzer's Disease]]''' and '''[[Hyperlipaemia - Horse|Hyperlipaemia]]''' |
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| ==Diagnosis== | | ==Diagnosis== |
| + | Diagnosis is made on clinical signs of cerebral dysfunction with evidence of hepatic insufficiency, in the absence of other potential causes for the neurological signs. |
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| ===Clinical Signs=== | | ===Clinical Signs=== |
− | Clinical signs vary depending on the severity of hepatic dysfunction, early signs are often subtle and may be missed. Clinical signs may be associated with feeding. | + | Clinical signs vary depending on the severity of hepatic dysfunction, and may be associated with feeding. |
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− | *Depression
| + | Four clinical stages have been described for hepatic encephalopathy: |
− | *Lethargy | + | * Stage I: Mild changes in mentation; this stage is usually missed in horses. |
− | *Head pressing | + | * Stage II: Depressed mental state, lethargy, behavioural changes, head pressing, ataxia and dysphagia. |
− | *Ataxia | + | * Stage III: Somnolent but rousable. Reactions may be very reduced or exaggerated. |
− | *Behavioural changes
| + | * Stage IV: Coma, Seizures are rare but may occur in the late stages of the condition. |
− | *Seizures | |
− | *Coma
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− | *Death
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− | Clinical signs associated with hepatic disease
| + | Additional clinical signs associated with hepatic disease: |
− | *Weight loos | + | *Weight loss |
| *Diarrhoea | | *Diarrhoea |
| *Icterus | | *Icterus |
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| ===Laboratory Tests=== | | ===Laboratory Tests=== |
| + | Haemotology and Biochemistry results will be consistent with hepatic disease; including increased GGT and SDH, [[Hypoalbuminaemia|hypoalbuminaemia]] and elevated [[Bile acids|bile acids]]. |
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| ===Biopsy=== | | ===Biopsy=== |
− | A liver biopsy can provide a definitive diagnosis of liver disease, a clotting profile should be carried out before taking an ultrasound-guided biopsy. | + | A liver biopsy can provide a definitive diagnosis of liver disease; a clotting profile should be carried out before taking an ultrasound-guided biopsy. |
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| ===Ultrasound=== | | ===Ultrasound=== |
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| ===Pathology=== | | ===Pathology=== |
− | See [[Hepatic Encephalopathy]] Pathology | + | See [[Hepatic Encephalopathy#Pathology|hepatic encephalopathy pathology]] |
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| ==Treatment== | | ==Treatment== |
− | With supportive therapy horses may recover from hepatic encephalopathy after 4-21 days. Treatment is only warranted | + | With '''supportive''' therapy horses may recover from hepatic encephalopathy after 4-21 days. Treatment is only warranted in acute cases likely to make a recovery. |
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− | Sedation is often necessary in cases of hepatic encephalopathy; An alpha 2 agonist at a low dose is usually effective. If the neurological signs are so severe that the horse is a danger to itself and others then immediste euthansia is indicated. | + | '''Sedation''' is often necessary in cases of hepatic encephalopathy; An alpha 2 agonist at a low dose is usually effective. If the neurological signs are so severe that the horse is a danger to itself and others then '''euthanasia''' may be indicated. |
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| + | Fluid deficits and acid base abnormalities should be corrected as necessary and hypoglycaemic animals should be given a 5% dextrose solution IV. High carbohydrate, low protein diets should be fed in small amounts and frequently. |
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| + | Lactulose, mineral oil and neomycin or metronidazole can be administered in an attempt to reduce the production and absorption of hepatic toxins. |
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| ==Prognosis== | | ==Prognosis== |
− | Prognosis is poor to severe but depend on the underlying disease; signs are potentially reversible if the initiating course can be corrected. | + | Prognosis is '''poor''' to severe but depends on the underlying disease; signs are potentially reversible if the initiating course can be corrected. |
− | Horses with hepatic disease showing neurological signs have a poorer prognosis than those showing only signs af hepatic dysfunction. However with appropriate supportive therapy 40% of horses survive for at least 6 months. Recovery may be incomplete and temporary. | + | Horses with hepatic disease showing neurological signs have a poorer prognosis than those showing only signs of hepatic dysfunction. However with appropriate supportive therapy 40% of horses survive for at least 6 months. Recovery may be incomplete and temporary. |
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| + | {{Learning |
| + | |literature search = [http://www.cabdirect.org/search.html?q=%28title%3A%28Hepatic%29+OR+title%3A%28liver%29+OR+title%3A%28Portosystemic%29%29+AND+%28title%3A%28Encephalopathy%29+OR+title%3A%28coma%29%29+AND+od%3A%28horses%29 Hepatic Encephalopathy in horses publications] |
| + | }} |
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| ==References== | | ==References== |
| * Bertone, J. (2006) '''Equine Geriactric Medicine and Surgery''', ''Elsevier'' | | * Bertone, J. (2006) '''Equine Geriactric Medicine and Surgery''', ''Elsevier'' |
| + | * Brown, C.M, Bertone, J.J. (2002) '''The 5-Minute Veterinary Consult- Equine'''', Lippincott, Williams & Wilkins'' |
| * Knottenbelt, D.C. '''A Handbook of Equine Medicine for Final Year Students''' ''University of Liverpool'' | | * Knottenbelt, D.C. '''A Handbook of Equine Medicine for Final Year Students''' ''University of Liverpool'' |
| + | * Mair, T., Love, S., Schumacher, J. and Watson, E. (1998) '''Equine Medicine, Surgery and Reproduction''' ''WB Saunders Company Ltd'' |
| * Merck & Co (2008) '''The Merck Veterinary Manual (Eighth Edition)''' ''Merial'' | | * Merck & Co (2008) '''The Merck Veterinary Manual (Eighth Edition)''' ''Merial'' |
| + | * Reed, S.M, Bayly, W.M, Sellon, D.C. (2004) '''Equine Internal Medicine''' (Second Edition) ''Saunders''. |
| * Rose, R. J. and Hodgson, D. R. (2000) '''Manual of Equine Practice''' (Second Edition) Sauders. | | * Rose, R. J. and Hodgson, D. R. (2000) '''Manual of Equine Practice''' (Second Edition) Sauders. |
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− | [[Category:To_Do_-_lizzyk]] | + | |
− | [[Category:Liver_Disorders_-_Horse]] | + | {{review}} |
− | [[Category:Neurological_Disorders_-_Horse]] | + | |
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| + | [[category:Expert_Review]] |
| + | [[Category:Liver Diseases - Horse]] |
| + | [[Category:Neurological Diseases - Horse]] |