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| − | ==Myositis==
| + | #redirect[[:Category:Muscles - Inflammatory Pathology]] |
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| − | *Inflammation of muscle
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| − | ===Bacterial myositis===
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| − | *Bacteria gain entry via:
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| − | **Direct penetration
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| − | **Blood stream
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| − | **Extension
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| − | *Lesions caused:
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| − | **Suppurative
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| − | **Serosanguinous
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| − | **Granulomatous
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| − | ====Abscesses====
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| − | *Caused by pyogenic bacteria
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| − | *Usually:
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| − | **[[Arcanobacter pyogenes|''Arcanobacterium pyogenes'']] in sheep and cattle
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| − | **[[Respiratory Bacterial Infections - Pathology#Strangles|''Streptococcus equi'']] in horses
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| − | **''[[Corynebacterium pseudotuberculosis]]'' in sheep and goats
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| − | **[[Pasteurella multocida|''Pasteurella multocida'']] causes cellulitis in cats
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| − | *Usually localised suppuration and necrosis of myofibres
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| − | *Occasionally my spread via the fascia
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| − | ====[[Black Leg]]====
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| − | ====[[Gas Gangrene|Gas gangrene]]====
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| − | ====[[Actinobacillosis|Wooden tongue]]====
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| − | ====[[Tuberculosis]]====
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| − | ====''[[Actinomyces bovis]]''====
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| − | *"[[Lumpy jaw]]"
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| − | ====[[Botryomycosis]]====
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| − | ===Viral myositis===
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| − | *Rare in the UK
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| − | ====[[Porcine encephalomyelitis]]====
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| − | ====[[Foot and Mouth Disease]]====
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| − | ====[[Bluetongue Virus|Bluetongue]]====
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| − | ===Parasitic myositis===
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| − | *Rare in domestic animals
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| − | ====Nematodes====
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| − | *[[Trichinella|'''''Trichinella''''']] larvae
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| − | *[[Ancylostomatoidea|''Ancylostoma'']] larvae
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| − | **Cause inflammation and [[Muscles Degenerative - Pathology#Necrosis|necrosis]]
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| − | *[[Ascaridoidea|Ascarid]] larvae
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| − | *[[Dirofilaria immitis|''Dirofilaria immitis'']] in dogs causing ischaemic myopathy due to [[Muscles Degenerative - Pathology#Ischaemia|infartcs]]
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| − | ====Cestodes====
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| − | *[[Taenia|''Taenia solium, '']] - cysticercosis in swine and humans
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| − | *[[Taenia|''T. ovis'']] - cysticercosis in sheep
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| − | *[[Taenia|''T. saginata'']] in cattle cysticercosis
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| − | *[[Taenia|''Multiceps serialis'']] in rabbits, primates coenurosis
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| − | *[[Echinococcus|''Echinococcus granulosus'']] hydatid disease in herbivores and humans
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| − | ====Protozoa====
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| − | *'''''[[Toxoplasma gondii]]'''''
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| − | *[[Neospora|'''''Neospora caninum''''']]
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| − | *[[Sarcocystis|'''''Sarcocystis''''']]
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| − | *[[Hepatozoon|'''''Hepatozoon americanum''''']]
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| − | *'''''[[Trypanosoma]]'''''
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| − | *'''''[[Babesia|Babesia bovis]]'''''
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| − | ====Arthropods====
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| − | *Dipterious larvae causing [[Myiasis|myiasis]]
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| − | *[[Hypoderma spp.|''Hypoderma'' spp.]] in cattle
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| − | **May occasionally burrow into muscle
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| − | ===Immune-mediated myositis===
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| − | ====Masticatory muscle myositis (MMM)====
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| − | *Occurs in dogs
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| − | *Tends to affect the masseter and temporalis muscles
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| − | *Autoantibodies selectively attack muscles of mastication (type IIM fibres)
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| − | *Acute stage = eosinophilic myositis
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| − | **Extremely swollen, painful, hard masticatory muscles
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| − | *Chronic stage = atrophic myositis
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| − | **Atrophy may occur without previous acute stage
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| − | *Grossly:
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| − | **Bilateral but not necessarily symmetrical
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| − | **At first, enlarged and oedematous muscles becominf dark red, firm with reddish streaks and yellowiss foci
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| − | *Histologically:
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| − | **Acute lesions:
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| − | ***Mainly eosinophilic infiltrate, few lymphocytes, [[Monocytes|monocytes]] and plasma cells
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| − | ***In recurrent disease plasma cells predominate
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| − | ***[[Muscles Degenerative - Pathology#Necrosis|Necrotic]] myofibres, [[Muscles Degenerative - Pathology#Atrophy|atrophy]] and attempted [[Muscle Regeneration|regeneration]]
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| − | **Chronic stage:
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| − | ***[[Muscles Degenerative - Pathology#Atrophy|Atrophy]] predominates
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| − | ***Fasciculi are shrunken
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| − | ***Condensation of stroma -> enlarged endomysium
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| − | ***Focal plasma cell and lymphocyte infiltration
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| − | ====[[Canine Dermatomyositis|Canine dermatomyositis]]====
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| − | ===Idiopathic myositis===
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| − | ====Canine polymyositis====
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| − | *DOES NOT include MMM above
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| − | *Rare
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| − | *Clinical signs:
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| − | **Muscle pain
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| − | **Fever
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| − | **Weakness, particularly in hind limbs
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| − | *Grossly:
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| − | **Inflammation is accompanied by muscle necrosis and regeneration
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| − | *Histologically:
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| − | **Inflammatory foci with lymphocytes, plasma cells and occasionally eosinophils
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| − | *Possibly immunological cause
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| − | *Single biopsy may not be enough to make the diagnosis as it tends to be multifocal and disseminated
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| − | *Lesions similar to some infectious causes (such as ''[[Toxoplasma gondii]]'')
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| − | ====Canine bilateral extraocular polymyositis====
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| − | *In Golden retrievers
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| − | *Very rare
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| − | *Clinical signs:
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| − | **Acute bilateral exophthalmos
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| − | *Involves only extraocular muscles except for retractor blbi
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| − | *Grossly:
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| − | **Swollen and pale extraocular muscles
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| − | *Histologically:
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| − | **Sterile myositis
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| − | **Multifocal necrosis of myofibres
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| − | **Lymphocytic, histiocytic and plasmacytic infiltrate with few [[Neutrophils|neutrophils]]
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| − | ====Bovine and ovine eosinophilic myositis====
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| − | *Unknown aetiology
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| − | *Major cell involved is eosinphil
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| − | *Usually noticed at slaughter - green muscle discoloration
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| − | *May be caused by degenteration of [[Sarcocystis|''Sarcocystis'' spp.]]
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| − | *Grossly:
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| − | **Green discolored areas, well demarcated
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| − | **Mostly in muscles of back and thighs
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| − | *Histologically:
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| − | **Massive eosinophil infiltration
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| − | **Muscle fibres may degenerate
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| − | **In old lesions - endimysial fibrosis, myofibre atrophy, some regeneration, lymphocytes, plasma cells, macrophages and few eosinophils
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| − | **Capsule may form
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| − | [[Category:Musculoskeletal System - Pathology]]
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