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| − | ===Bone infections in general===
| + | #REDIRECT[[:Category:Bones - Inflammatory Pathology]] |
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| − | *'''Caused by''':
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| − | **Bacteria most commonly (e.g. [[Mandibular Osteomyelitis|lumpy jaw]] in cattle due to ''[[Actinomyces bovis]]'')
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| − | **Viruses, fungi and protozoa less commonly
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| − | *'''Routes of infection''':
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| − | **“Inoculated” at time of [[Bones Fractures - Pathology|fracture]]
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| − | **Extension from other infected sites ([[Sinusitis|sinuses]], middle ear, [[Joints Inflammatory - Pathology|joints]])
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| − | **Haematogenous (young farm animals)
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| − | *'''Gross lesions'''
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| − | **Suppurative exudate (in bacterial infection), necrosis, bone proliferation, pathological fractures
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| − | **Dead bone portions may be separated from blood supply and form bone sequestra
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| − | *'''Consequences'''
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| − | **Extension to adjacent bone
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| − | **Haematogenous spread to other bones and soft tissue
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| − | **Pathologic fractures
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| − | **Sinus tracts to exterior
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| − | *'''Osteitis''' = inflammation of bone
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| − | *'''Periostitis''' = inflammation of periosteum, usually develops from infection in adjacent tissues
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| − | *'''Osteomyelitis''' = inflammation of medullary cavity
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| − | ===Osteitis===
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| − | *E.g.: [[Fusobacterium necrophorum|''Fusobacterium necrophorum'']] in the foot, [[Respiratory Bacterial Infections - Pathology#Necrotic laryngitis|calf diphteria]], bite wounds, extension from paranasal sinuses, compound fractures, extensions from infections in the joints, [[Alveolar Periostitis|periodontal disease]], [[Respiratory Bacterial Infections - Pathology#Atrophic Rhinitis|Atrophic rhinitis]]
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| − | ===Osteomyelitis===
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| − | [[Image:Cattle localised osteomyelitis with sequestrum.jpg|right|thumb|100px|<small><center>Localised osteomyelitis plus sequestrum (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]]
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| − | *Mainly due to haematogenous spread in young animals
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| − | *Often as an extension from [[Joints Inflammatory - Pathology#Arthritis|suppurative arthritis]]
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| − | *Usually isolated: ''[[Actinomyces pyogenes]]'', [[Salmonella|''Salmonella'']], [[Escherichia coli|''E.coli'']], [[Klebsiella|''Klebsiella'']], [[:Category:Streptococcus species|''Streptococci'']]
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| − | *Metaphyses and epiphyses mostly affected
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| − | *Most infections are exacerbated by host response
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| − | *Pathogenesis:
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| − | **Prostaglandin and cytokines stimulate [[Bones - normal#Normal structure|osteoclastic]] bone resorption
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| − | **Blood vessel occlusion and tissue necrosis -> lack of removal of agent and cartilage -> cartilage thickening + persistance of infection
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| − | *Affected area may be surrounded by fibrous inflammatory tissue
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| − | *Metaphyseal abscesses may develop
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| − | *Sequestra may also develop -> surrounded by [[Granulation Tissue|granulation tissue]]
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| − | **Isolated from osteoclastic resorption
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| − | **May persist for long time
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| − | **Obstruct repair
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| − | *'''Vertebral osteomyelitis'''
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| − | **Lesions may affect the spinal cord
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| − | **Usually due to ''[[Actinomyces pyogenes]]''
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| − | **Suppurative inflammation may cause fracture of vertebral body -> dorsal displacement -> damage to spinal cord
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| − | **May form encapsulated abscess protruding into spinal canal -> spinal cord compression
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| − | *'''''Actinomycosis'''''
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| − | **= '''Lumpy jaw''' in cattle
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| − | **Caused by ''[[Actinomyces bovis]]''
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| − | ***Gram positive, branching, filamentous
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| − | ***Obligatory parasite of mucous membranes of [[Oropharynx - Anatomy & Physiology|oropharynx]]
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| − | ***Surface tissue is usually injured for infection to occur
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| − | ***[[Mandibular Osteomyelitis|Osteomyelitis of mandible]] -> destruction of bone -> replacement by fibrous tissue with pyogranulomatous nodules cotaining 'club colonies' of bacteria
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| − | ***Suppurative osteomyelitis
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| − | ***Fistulous tracts may discharge onto skin and into [[Oral Cavity Overview - Anatomy & Physiology|oral cavity]]
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| − | ***Excessive periosteal bone formation
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| − | ***Greatly enlarged mandible
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| − | ===Periostitis===
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| − | *Chronic periostitis - pockets of exudate and irregular new bone fomation
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| − | ===Panosteitis===
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| − | [[Image:Panosteitis.jpg|right|thumb|100px|<small><center>Panosteitis (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]]
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| − | *Typically young large or giant breeds
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| − | *75% of cases in German shepherd dogs, 5-12 months old
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| − | *Clinical signs:
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| − | **Shifting lameness
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| − | **Often eosinophilia in peripheral blood
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| − | *Usually self-limiting in one to several months
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| − | *Grossly:
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| − | **Foreleg long bone '''diaphyses''' affected (multiple bones in 50% of cases)
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| − | **Increased bone formation in the medullary cavity and often in the periosteum
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| − | *Contast with [[Bones Hyperplastic and Neoplastic - Pathology#Hypertrophic osteodystrophy|'''hypertrophic osteodystrophy''']]
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| − | [[Category:Musculoskeletal System - Pathology]]
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