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Photosensitisation (view source)

Revision as of 13:11, 10 August 2010

923 bytes removed ,  13:11, 10 August 2010
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==Clinical signs==
 
==Clinical signs==
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The condition is characterised by 'sunburn-like' lesions that are confined to unpigmented areas of the skin
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The condition is characterised by clearly demarcated 'sunburn-like' lesions that are confined to unpigmented or hairless areas of the skin. The nose, lips, ears, muzzle and udder are commonly affected areas. In the acute stages, the affected area(s) becomes erythematous and oedematous with exudation and crust formation. Animals may be pruritic or painful.
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**due to the effect of UV light on a photodynamic agent (PDA) present in the skin, such as is '''phylloerythrin''' derived from chlorophyll
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**therefore, the disease occurs mostly in those animals consuming large quantities of grass
 
**therefore, the disease occurs mostly in those animals consuming large quantities of grass
 
**the UV light is changed to a longer wavelength which produces the necrosis of the skin
 
**the UV light is changed to a longer wavelength which produces the necrosis of the skin
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**Blue-green algae
 
**Blue-green algae
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===Clinical Signs===
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*localised to lightly pigmented skin areas
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*clear cut demarcation of affected area
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*teats, muzzle, ears
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*skin only
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*skin and liver signs
      
===Microscopically===
 
===Microscopically===
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*'''Primary'''
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**Ingestion of photodynamic substance from plants (''Hypericum perforatum'' and ''Fagopyrum sagittatum'' - buckwheat) or fungal contaminants
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**Induced by drug administration - phenothiazines, tetracyclines, thiazides, sulphonamides
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*'''Abnormal porphyrin metabolism'''
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**Bovine congenital porphyria
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**Bovine erythropoeitic protoporphyria
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*'''Hepatogenous'''
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**Impaired excretion of phylloerythrin (chlorophyl metabolism product) due to hepatic disease
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**[[Biliary Tract - Obstruction|Biliary obstruction]]
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**Inherited defects
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**Hepatic injury due to toxic plants or fungal contaminants, chemicals or some infectious agents
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*Grossly:
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**In areas lacking hair or pigment
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**Erythema, oedema -> blisters, exudation, necrosis, sloughing or keratitis
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*Microscopically:
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**Subepidermal vesicles
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**Ulceration
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**Secondary infection
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[[Category:Teeth_-_Developmental_Pathology]]
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[[Category:Liver_-_General_Pathology]]
 
[[Category:Liver_-_General_Pathology]]
 
[[Category:To_Do_-_SophieIgnarski]]
 
[[Category:To_Do_-_SophieIgnarski]]
Signarski
906

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