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| − | ==Introduction==
| + | #redirect[[Cobalt Deficiency - Sheep]] |
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| − | White liver disease in sheep is a form of fatty liver disease associated with cobalt deficiency.
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| − | Disease occurs in areas of low soil cobalt which can be found in parts of the UK and Australia.
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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]].
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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.
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| − | Propionate is the major source of glucose in ruminants and thus glucose deficiency and starvation occur.
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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]]
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| − | [[Category:To_Do_-_Alimentary]][[Category:To Do - Medium]]
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| − | [[Category:Liver Diseases - Sheep]]
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