Infarction
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An infarct is an area of coagulative necrosis results due to sudden blockage of an end artery which has no collateral circulation.
Causes
Thrombus / embolus
Ergot poisoning
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Smooth muscle contraction
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Narrowing of blood vessel
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Ischaemia
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Seen in extremities (legs, ears, tail, wattles)
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Hypotension ® Shock ® Ischaemia ® Brain infarction
Pathogenesis
Thrombus (blocking of end artery)
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Ischaemia ® capillaries dilate to increase blood supply
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Hypoxia Area red color [Red infarct]
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Damage to endothelium
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Haemorrhage
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>2 hours - Fusion of RBCs into homogenous mass
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Degeneration of cells
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24hours - Coagulation necrosis of cells
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72hours - Lysis of RBCs
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Release of haemoglobin
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Loss red color [Pale infarct]
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Inflammation
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Scar (yellow / brown due to haemosiderin
Macroscopical appearances
Infarcts of kidneys
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Common in cows and pigs
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Yellow or pale
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Wedge shaped – seen in cortex
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Apex at arcuate arteries
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Base at capsular end of cortex
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Appears as healed, depressed areas
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Causes
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Cardiac vegetations – Corynebacterium pyogenes, streptococci
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Cows – very common – emboli of uterine vein after parturition
Infarcts of spleen
Infarction of intestines
Volvulus, intussuception, strangulation
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CVC
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Necrosis
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Gangrene
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Sequelae
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Fatal
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Toxaemia
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Peritonitis
Infartion of brain
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Common in man
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Due to arteriosclerosis
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Animals – Dogs – automobile accidents
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Cerebral infarction
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Softening → Myelin engulfed by microglia – “ Compound granular corpuscles”
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Organization or cyst formation (neuroglial cells)
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Cyst with yellow fluid “Apoplectic cysts”
Infarcts of heart
Infarcts of liver
Infarcts of lungs
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Common
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Cone shaped
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Red color
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Causes
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Emboli from
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Cows – Uterine veins & posterior vena cava (Abscess)
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Horses – Mesenteric veins
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Pigs – Pulmonary veins (Hog cholera)
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Hypostatic congestion
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Chronic venous congestion
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Cattle and sheep – Pasteurella infection → Pulmonary infarction (Haemorrhagic septicaemia)
Sequelae of infarcts
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Last modified: Wednesday, 7 December 2011, 9:11 AM