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| − | ===Ischaemia=== | + | ===[[Muscle Ischaemia]]=== |
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| − | *Firstly [[Muscles Degenerative - Pathology#Necrosis|segmental necrosis]]
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| − | *-> death of satellite cells
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| − | **Causes [[Muscle Regeneration|regeneration]] but myoblast precursors have to be recruited from viable fibres
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| − | *-> death of all cells
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| − | *Mostly healed by fibrosis and scar formation
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| − | *May attempt regeneration by [[Muscle Regeneration|budding]]
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| − | Main causes:
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| − | *'''Vascular occlusion'''
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| − | **Infarction from embolism is rare due to collateral circulation
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| − | **Extension of infarcts depends on size of vessels occluded
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| − | ***Small capillaries -> segmental [[Muscles Degenerative - Pathology#Necrosis|necrosis]]
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| − | ***Large arteries -> whole muscle areas, including sattelite cells, are killed
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| − | **Healed by fibrosis
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| − | **May be due to:
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| − | ***Blockage of iliac arteries by aortic-iliac thrombosis in horses
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| − | ***Blockage of aortic bifurcation in cats
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| − | ***[[Dirofilaria immitis|''Dirofilaria immitis'']] arteritis in dogs
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| − | ***Vasculitis due to [[Reoviridae#Bluetongue Virus|bluetongue virus]] in sheep
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| − | ***[[Haemorrhage#Purpura haemorrhagica|'''Equine purpura haemorrhagica''']]
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| − | ****Non-contagious, sporadic
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| − | ****Grossly:
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| − | *****Subcutaneous oedema
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| − | *****Scattered haemorrhagic foci throughout skin and muscles
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| − | *****Vasculitis -> infarcts of muscles
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| − | ****May cause myoglobinuria if extensive
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| − | ****Possibly immune mediated
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| − | ****In horses post [[:Category:Streptococcus species|streptococal]] infection, especially [[Respiratory Bacterial Infections - Pathology#Strangles|strangles]]
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| − | *'''External pressure'''
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| − | **During prolonged recumbency, e.g. anaesthesia, inability to rise, or due to too tightly fitting bandages or casts
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| − | **Post anaesthesia myopathy especially in horses
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| − | ***Dorsal recumbancy -> gluteals and longissimus ischaemia
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| − | ***Lateral recumbancy -> triceps brachii, pectoralis, deltoideus and brachiocephalicus ischaemia
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| − | **Caused by pressure on muscle > perfusion pressure of capillaries
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| − | **Downer cows - vetral recumbency -> ischaemia of pectoral muscles and muscles of limbs tucked under the animal
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| − | **Pregnant ewes with twins or triplets -> internal abdominal oblique muscle ischaemic necrosis -> potential rupture
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| − | *'''Muscle swelling''' where it cannot expand
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| − | **E.g. supracoracoid muscle infarction in some breeds of turkeys after flapping their wings
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| − | ***Surrounded by inelastic fascial sheath and bone
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| − | [[Category:Muscles - Degenerative Pathology]]
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| | ==Trauma== | | ==Trauma== |