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, 12:09, 3 March 2011
[[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>]]
*Mainly due to haematogenous spread in young animals
*Often as an extension from [[Joints Inflammatory - Pathology#Arthritis|suppurative arthritis]]
*Usually isolated: ''[[Actinomyces pyogenes]]'', [[Salmonella|''Salmonella'']], [[Escherichia coli|''E.coli'']], [[Klebsiella|''Klebsiella'']], [[:Category:Streptococcus species|''Streptococci'']]
*Metaphyses and epiphyses mostly affected
*Most infections are exacerbated by host response
*Pathogenesis:
**Prostaglandin and cytokines stimulate [[Bones - Anatomy & Physiology|osteoclastic]] bone resorption
**Blood vessel occlusion and tissue necrosis -> lack of removal of agent and cartilage -> cartilage thickening + persistance of infection
*Affected area may be surrounded by fibrous inflammatory tissue
*Metaphyseal abscesses may develop
*Sequestra may also develop -> surrounded by [[Granulation Tissue|granulation tissue]]
**Isolated from osteoclastic resorption
**May persist for long time
**Obstruct repair
*'''Vertebral osteomyelitis'''
**Lesions may affect the spinal cord
**Usually due to ''[[Actinomyces pyogenes]]''
**Suppurative inflammation may cause fracture of vertebral body -> dorsal displacement -> damage to spinal cord
**May form encapsulated abscess protruding into spinal canal -> spinal cord compression
*'''''Actinomycosis'''''
**= '''[[Lumpy jaw]]''' in cattle
**Caused by ''[[Actinomyces bovis]]''
***Gram positive, branching, filamentous
***Obligatory parasite of mucous membranes of [[Oropharynx - Anatomy & Physiology|oropharynx]]
***Surface tissue is usually injured for infection to occur
***[[Mandibular Osteomyelitis|Osteomyelitis of mandible]] -> destruction of bone -> replacement by fibrous tissue with pyogranulomatous nodules cotaining 'club colonies' of bacteria
***Suppurative osteomyelitis
***Fistulous tracts may discharge onto skin and into [[Oral Cavity Overview - Anatomy & Physiology|oral cavity]]
***Excessive periosteal bone formation
***Greatly enlarged mandible
[[Category:Bones - Inflammatory Pathology]]