MSK 2 Flashcards
What are the two broad categories of inflammatory bone diseases?
infectious and non infectious
what kind of viruses cause viral bone lesions in young growing animals with open physes?
pestiviruses like BVDV, classical swine fever, canine distemper, and border disease virus
what is the pathogenesis of biral bone lesions?
viruses damage osteoclasts–>abnormal osteoclast activity–> metaphyseal trabeculae are not remodelled –> metaphyseal osteosclerosis/growth retardation lattices
what is the difference between osteitis and osteomyelitis?
osteitis is inflammation of the bone, osteomyelitis is inflammation of the bone and medullary cavity
osteomyelitis is most often associated with
bacterial or fungal infections
name 3 sources of bone infections
- direct introduction like via open fracture or penetrating wound
- extension from soft tissues like cellulitis, periodontitis, etc
- hematogenous spread
sometimes with bacterial infection you can get embolic osteomyelitis. Describe the pathogenesis
septicemia–>bacteria spread via the blood–>the blood supply to the growth plate involves capillaries that make sharp bends which are prone to turbulence, thrombosis, and slow flow–>bacteria can lodge here and proliferate and spread locally–>leading to suppurative osteomyelitis
what is this lesion showing?
embolic osteomyelitis from a bacterial infection
list some comon bacterial species associated with embolic osteomyelitis
trueperella pyogenes, staphylococcus sp, escherichia coli, salmonella enterica
what is this arrow pointing to? this is tissue from a foal
metaphyseal suppurative osteomyelitis (pus above and below the growth plate)
bacterial osteomyelitis is also called lumpy jaw in cattle and is caused by
actinomyces bovis
what is the pathogenesis of actinomyces bovis?
damge to the oral mucosa provides portal of entry–> soft tissue infection develops–> extension of infection into the mandible–> pyogranulomatous osteomyelitis
list 3 gross lesions of lumpy jaw
- necrotic tracts of pyogranulomatous inflammation, may drain as thick pus to the skin (fistula)
- concurrent periosteal bone proliferation and lysis
- honeycomb appearance of the mandible
this is a cow mandible. what disease is this and what is the etiology?
lumpy jaw/bacterial osteomyelitis
actinomyces bovis
this is tissue from a cow. what is your suspected diagnosis?
lumpy jaw/bacterial osteomyelitis. you can see the pockets of swelling, fibrous scar tissue, and tracts of pyogranulomatous inflammation
how does fungal osteomyelitis usually appear?
pyogranulomatous to granulomatous osteomyelitis with bone lysis and periosteal new bone formation
what is an important differential diagnosis for fungal osteomyelitis?
bone neoplasia
what is one important consideration when you are attempting to diagnose fungal osteomyelitis?
it is less common than bacterial and the risk is very dependent on geographical location and the specific species common in certain areas
what are the usual clinical signs associated with fungal osteomyelitis?
fever, weight loss, and bone pain
what are two things this could be?
fungal osteomyelitis or bone neoplasia
describe the pathogenesis of fungal osteomyelitis using blastomyces as your pathogen
blastomyces inhalation–>hematogenous spread and apparent predilection for lungs (fungal pneumonia) and less often appendicular bones–>pyogranulomatous osteomyelitis
what are 3 gross lesions to look for with fungal osteomyelitis?
- periosteal new bone thickens the bone contour
- loss of cortical bone (cortex gone)
- suppurative to pyogranulomatous material present
what is osteonecrosis and what causes it? What is the pathogenesis? What is the result?
necrosis of the bone, causes can be infection, trauma, neoplasia, frostbite, etc.
pathogenesis: bone lesions that causes damage to the blood supply causing ischemia and infarction
area is slowly removed by osteoclasts so if it is not removed a sequestrum can form. the outcome depends on the blood supply, the size, and the proximity to viable tissue