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*Australia and Europe
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==Introduction==
*young lambs on lush pasture
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*clinical signs
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White liver disease in sheep is a form of fatty liver disease associated with cobalt deficiency.
**ill thrift
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Disease occurs in areas of low soil cobalt which can be found in parts of the UK and Australia.
**anorexia
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Cobalt is used by the rumen microflora to synthesise vitamin B12 (cobalamin). Cobalamin is a co-enzyme for methylmalonyl CoA mutase, an enzyme involved in the pathway through which propionate is metabolised into glucose. Vitamin B12 is also important in the [[Erythropoiesis#Nutritional factors|formation of new erythrocytes]].
**jaundice
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Cobalt deficiency leads to the accumulation of methylmalonyl CoA, or methylmalonic acid, which is converted to branched chain fatty acids that accumulate in the liver and cause damage.
**photosensitisation
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Propionate is the major source of glucose in ruminants and thus glucose deficiency and starvation occur.
*treatment
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**responsive to Vitamin B12 and cobalt
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==Clinical signs==
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Disease is most commonly seen in weaned lambs at pasture in late summer/autumn.
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Cobalt deficiency presents as:
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*ill-thrift  
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*anorexia
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*emaciation
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*bilateral serous ocular discharge
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*pale mucous membranes
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The liver damage can lead to:
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*[[Photosensitisation|photosensitisation]] (scaly ears)
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*diarrhoea
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*nervous signs ([[Hepatic Encephalopathy]])
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==Diagnosis==
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Clinical signs are suggestive.
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Clinical pathology may reveal:
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*mild normocytic, normochromic anaemia
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*elevated liver enzymes (GGT, AST)
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*reduced serum levels of vitamin B12
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Liver analysis:
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*reduced levels of cobalt and vitamin B12
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*Grossly: pale, fatty and friable parenchyma
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*Histopathology: Hepatic lipidosis, bile duct proliferation
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Flock levels:
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*Individual variation in serum vitamin B12 levels is high and a minimum of 7 sheep should be sampled.
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*There is little variation in liver vitamin B12 concentrations and 3 samples collected from casualty or slaughterhouse animals can be used to monitor the flock cobalt status.
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==Treatment and prevention==
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Immediate treatment: vitamin B12 injection or oral cobalt supplementation <br>
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Long-term prevention: Pasture analysis and identification of cobalt deficient areas.
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Cobalt supplementation via drenches, licks, pasture fertilization, cobalt bolus administration.
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==References==
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D.G. Pugh (2002) Sheep and Goat Medicine, Elsevier Health Sciences <br>
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J. Brugère-Picoux (2004) Maladies des moutons (2nd Edition), Editions France Agricole <br>
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P.J. Mitchell et al (1982) White liver disease of sheep, Australian Veterinary Journal 58, 181-4 <br>
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S. Kennedy et al (1997) Histopathologic and ultrastructural alterations of white liver disease in sheep experimentally depleted of cobalt, Veterinary Pathology 34, 575-84 <br>
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N. Sargison (2001) Cobalt deficiency in lambs, NADIS disease bulletin
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[[Category:Liver_-_Degenerative_Pathology]]
 
[[Category:Liver_-_Degenerative_Pathology]]
 
[[Category:To_Do_-_Alimentary]][[Category:To Do - Medium]]
 
[[Category:To_Do_-_Alimentary]][[Category:To Do - Medium]]
 
[[Category:Liver Diseases - Sheep]]
 
[[Category:Liver Diseases - Sheep]]
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