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| | ==[[Liver response to injury]]== | | ==[[Liver response to injury]]== |
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| − | ===Necrosis=== | + | ===[[Liver Necrosis]]=== |
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| − | ====Causes====
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| − | *severe metabolic disturbances [as seen in degenerative pathology link?]
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| − | *toxic substances [link?]
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| − | *nutritional deficiencies
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| − | *action of micro-organisms
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| − | ====Histological patterns====
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| − | *[[Liver - Anatomy & Physiology|Liver]] cell necrosis has been classified on an anatomic basis with reference to the distribution of the lesion
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| − | =====Random foci (focal)=====
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| − | *microscopic foci of necrosis not related to any particular part of the [[Liver - Anatomy & Physiology|liver]] lobule
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| − | *can be due to a variety of insults
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| − | **systemic viral, bacterial,and parasitic infections
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| − | **result of bacteria being absorbed from the gut
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| − | *examples
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| − | **Equine herpes virus infection
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| − | ***in aborted foetuses
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| − | **Salmonellosis
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| − | ***in calves
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| − | **Toxoplasmosis (miliary)
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| − | ***in dogs and cats
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| − |
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| − | =====Zonal necrosis=====
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| − | *necrosis occurring mainly in a part of the lobule and further subdivided according to whether the lesions are situated centrally, peripherally, or in the mid-zone of the lobule
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| − | *due to anoxia
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| − | ======Periacinar (centrilobular)======
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| − |
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| − | *most common
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| − | *main reason is because the hepatocytes in this zone are furthest away from the incoming blood supply
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| − | **therefore less oxygenated and relatively anoxic
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| − | *reported to contain the greatest number of enzymes responsible for metabolising sunstances to more toxic metabolites capable of killing the hepatocytes
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| − | *hypoxic states and toxic substances predominate in this type of necrosis
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| − | *some viral conditions cause this necrosis
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| − | **eg Infectious Canine Hepatitis
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| − | *poisons
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| − | **eg carbon tetrachloride
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| − |
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| − | ======Midzonal======
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| − | *rare
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| − | *in pigs with alfatoxicosis
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| − | *'Yellow Fever' in man
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| − |
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| − | ======Periportal (centroacinar)======
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| − | *rare
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| − | *eg phosphorous poisoning
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| − |
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| − |
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| − | =====Massive necrosis=====
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| − | *necrosis of large areas of [[Liver - Anatomy & Physiology|liver]] cells comprising many lobules (complete acinus or several acini) and sometimes involving almost the whole organ
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| − | *some cases of ICH infection or carbon tetrachloride poisoning, the severity of the injury replacing the zonal pattern
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| − | ======Subacute cytolytic necrosis======
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| − | *a condition in the dog
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| − | *aetiology is entirely unknown
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| − | *Clinical
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| − | **acute abdominal pain
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| − | **collapse
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| − | **invariably jaundice
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| − | *Gross
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| − | **[[Liver - Anatomy & Physiology|Liver]] is normal or reduced in size
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| − | *Microscopically
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| − | **severe necrosis
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| − |
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| − | ======''Hepatosis dietica''======
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| − | *similar condition to subacute cytolytic necrosis
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| − | *occurs in rapidly growing pigs
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| − | *related to diet
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| − | **fed on large quantities of grain concentrates
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| − | **poor quality or low quantity protein supplements
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| − | *Cause
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| − | **nutritional deficiencies of selenium and Vitamin E, and probably amino acids
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| − | **triggering mechanism is environmental stress
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| | ===Regeneration=== | | ===Regeneration=== |