Difference between revisions of "Bones Inflammatory - Pathology"
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===Osteomyelitis=== | ===Osteomyelitis=== | ||
Revision as of 12:08, 3 March 2011
Osteomyelitis
- Mainly due to haematogenous spread in young animals
- Often as an extension from suppurative arthritis
- Usually isolated: Actinomyces pyogenes, Salmonella, E.coli, Klebsiella, Streptococci
- Metaphyses and epiphyses mostly affected
- Most infections are exacerbated by host response
- Pathogenesis:
- Prostaglandin and cytokines stimulate 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
- 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
- Surface tissue is usually injured for infection to occur
- 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
- Excessive periosteal bone formation
- Greatly enlarged mandible
Periostitis
- Chronic periostitis - pockets of exudate and irregular new bone fomation
Panosteitis
- Typically young large or giant breeds
- 75% of cases in German shepherd dogs, 5-12 months old
- Clinical signs:
- Shifting lameness
- Often eosinophilia in peripheral blood
- Usually self-limiting in one to several months
- Grossly:
- Foreleg long bone diaphyses affected (multiple bones in 50% of cases)
- Increased bone formation in the medullary cavity and often in the periosteum
- Contast with hypertrophic osteodystrophy