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'''''PRECAUTION'': infective viral particles may be present in CNS and other tissues'''.
 
'''''PRECAUTION'': infective viral particles may be present in CNS and other tissues'''.
 
The brain and spinal cord are typically grossly normal, but vascular congestion and discolouration of the CNS may be seen.  Histologically the entire brain is affected by nonseptic mononuclear cell and neutrophilic inflammation.  Severe lesions are noted in the cerebral cortex, thalamus and hypothalamus.  Mononuclear meningitis, neuronal degeneration, gliosis and perivascular cuffing with mononuclear cell and neutrophilic infiltration are evident.  Immunohistochemistry can be diagnostic.  Liquefactive necrosis and haemorrhage of the cerebral cortex, atrophy of the pancreatic acinar cells and hyperplasia of the pancreatic duct cells commonly occur with VEE.
 
The brain and spinal cord are typically grossly normal, but vascular congestion and discolouration of the CNS may be seen.  Histologically the entire brain is affected by nonseptic mononuclear cell and neutrophilic inflammation.  Severe lesions are noted in the cerebral cortex, thalamus and hypothalamus.  Mononuclear meningitis, neuronal degeneration, gliosis and perivascular cuffing with mononuclear cell and neutrophilic infiltration are evident.  Immunohistochemistry can be diagnostic.  Liquefactive necrosis and haemorrhage of the cerebral cortex, atrophy of the pancreatic acinar cells and hyperplasia of the pancreatic duct cells commonly occur with VEE.
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IN VEE there may be damage to other organs such as the pancreas, liver and heart.
 
IN VEE there may be damage to other organs such as the pancreas, liver and heart.
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Gross pathological lesions are rarely observed in horses and, if present, consist only of the congestion of the brain and meninges. Ecchymotic haemorrhages of traumatic origin may be observed. Microscopic lesions are usually found throughout the central nervous system and can be diagnostic. There is widespread evidence of a severe inflammatory response involving the grey matter. Neuronal degeneration with infiltration by polymorphonuclear leukocytes, diffuse and focal gliosis, and perivascular cuffing with lymphocytes and neutrophils are seen. Also observed are neuronophagia and liquefaction of the neuropil. The extent of the lesions depends on the severity of the infection and the duration of the neurological involvement (16).
    
====Differential diagnosis====
 
====Differential diagnosis====
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