MSK pt 2 Flashcards
What animals are affected by viral bone lesions?
young growing animals with open physes
what is the pathogenesis of viral bone lesions?
- viruses damage osteoclasts
- abnormal osteoclast activity
- metaphyseal trabeculae are not remodelled = metaphyseal osteosclerosis/growth retardation lattices
which family of viruses commonly cause viral bone lesions?
pestiviruses
what is osteosclerosis?
disorder characterized by abnormal hardening of bone and elevation of bone density
What is the lesion in this bone? likely cause?
metaphyseal osteosclerosis
pestivirus
Define these terms:
1. osteitis
2. osteomyelitis
- inflammation of the bone
- inflammation of the bone and medullar cavity
osteomyelitis is most often associated with ___ or ____ infections.
bacterial, fungal
what are the 3 sources of bone infections?
- direct introduction (penetrating wound/open fx)
- extension from ST (cellulitis, periodontitis, otitis media)
- hematogenous spread
what is embolic osteomyelitis?
the blood supply to the physis includes capillaries that make sharp bends, which are prone to turbulence, thrombosis, and slow flow. This means that bacteria that get into the blood supply can lodge in these bends and proliferate, causing osteomyelitis (suppurative)
What is the pathogenesis of embolic osteomyelitis?
- source of bacteria
- bacteria spread hematogenously
- bacteria lodge in physeal capillaries
- bacteria proliferate and spread locally
- suppurative osteomyelitis develops
In embolic osteomyelitis, bacteria lodge in the capillaries and form _____.
microabsecces
What is the lesion in this bone?
embolic osteomyelitis/suppurative osteomyelitis
embolic osteomyelitis affects which animals most?
neonatal calves, lambs, foals
what are the common bacterial species that cause embolic osteomyelitis?
Trueperella pyogenes, Staphylococcus sp, Escherichia coli, Salmonella enterica
What is the lesion in this bone?
Suppurative osteomyelitis
What is the etiology of Lumpy Jaw?
Actinomyces bovis
what is the pathogenesis of lumpy jaw?
- damage to oral mucosa provides port of entry (ex. trauma from foreign bodies, coarse feed, periodontitis/dental disease/tooth eruptions)
- ST infection
- extension into mandible
- pyogranulomatous osteomyelitis
What are the gross lesions of lumpy jaw?
- necrotic tracts of pyogranulomatous inflammation, may drain as thick pus to the skin surface (fistula)
- concurrent periosteal bone proliferation and lysis
- honeycomb appearance
This is a mandible (idk what species). What is the lesion?
lumpy jaw
What caused this lesion? What is the pathology called?
Actinomyces bovis
Lumpy jaw
What is the lesion and pathology?
Pyogranulomatous osteomyelitis
Lumpy jaw
what types of osteomyelitis are seen with fungal osteomyelitis?
pyogranulomatous to granulomatous
what is the most common differential diagnosis when it comes to fungal osteomyelitis?
bone neoplasia
fungal osteomyelitis is ____ (more/less/the same) common than bacterial myelitis. The risk is ____ and ____ dependent.
less common
geographically, species
what are the clinical signs of fungal osteomyelitis?
fever, weight loss, bone pain
What is this picture showing?
fungal osteomyelitis (pyogranulomatous/granulomatous osteomyelitis)
what is the pathogenesis of fungal osteomyelitis caused by Blastomyces?
- inhalation
- hematogenous spread and apparent predilection for lungs (fungal pneumonia) and less often appendicular bones
- granulomatous osteomyelitis
What are the three species of fungus that commonly cause fungal osteomyelitis, and which species are affected by each?
- Blastomyces dermatitidis – dogs
- Coccidioides spp – horses, dogs, cats, llamas
- Cryptococcus spp – cats! (esp.), dogs, horses
what are the common gross lesions with fungal osteomyelitis?
periosteal new bone thickens bone contour
loss of cortical bone (lysis)
suppurative to pyogranulomatous material
what is osteonecrosis and what are the causes?
bone necrosis
infection (esp!), trauma (fx, neoplasia, frostbite)
what is the pathogenesis of osteonecrosis?
bone lesion that causes damage to blood supply, leading to ischemia and infarction
You have a bone with osteonecrosis. What are the next steps that the bone takes? what does the outcome depend on?
bone tries to remove necrotic tissue by osteoclasts
if it can’t, then a sequestrum is formed
outcome depends on blood supply, size, and proximity to viable tissue
what is a sequestrum? what is a bone sequestrum specifically?
piece of necrotic tissue that the body cannot absorb
fragment of necrotic bone that are isolated from blood supply (body can’t absorb)
what is the arrow pointing to? if this lesion isn’t dealt with, what will occur?
area of necrosis in bone
sequestrum will form if necrosic tissue isn’t removed by osteoclasts
bone sequestra are almost always associated with ____!
inflammation
what are the causes of bone sequestra?
comminuted fxs creating bone fragments, osteomyelitis
why are bone sequestra bad?
they persist long-term and can interfere with healing –> non-union fx
What is the arrow pointing to?
bone sequestrum
what age/species of animal does metaphyseal osteopathy affect?
young (<6 mo) large and giant breed dogs
Describe the lesions that come with metaphyseal osteopathy?
initially: bilaterally symmetrical suppurative and fibrinous osteomyelitis of metaphysis of multiple long bones, separation (fx) of metaphysis due to inflammation/necrosis
has a “double growth plate” appearance (double radiolucency parallel to physis)
chronically: periosteal new bone