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
How do you treat metaphyseal osteopathy? what is the cause?
spontaneously resolve
unknown cause
You see this lesion in a 4 month old Bernese Mountain Dog. What is it?
Metaphyseal osteopathy
What is aseptic necrosis?
osteonecrosis that is not associated with infection
What is the other name for aseptic necrosis of the femoral head?
Legg-Calvé-Perthes Disease
aseptic necrosis of the femoral head:
1. affects who?
2. pathogenesis?
- mini dog breeds
- femoral head infarction –> necrotic bone resorbed by osteoclasts –> articular cartilage collapses
describe the lesions associated with aseptic necrosis, specifically of the femoral head
articular surface of the femoral head is irregular/bumpy because the subchondral bone has undergone osteonecrosis
This is the femoral head of a miniature poodle. What do you think is going on?
Aseptic necrosis of the femoral head
Hypertrophic osteopathy:
1. AKA?
2. who is affected?
3. pathogenesis?
- hypertrophic pulmonary osteopathy
- dogs mainly, rarely horses and other spp.
- unknown
Describe the lesions of hypertrophic osteopathy.
progressive periosteal new bone formation affecting distal limbs
** typically associated with concurrent intrathoracic disease (pneumonia, lung tumors)
How do you treat hypertrophic osteopathy?
it regresses if the primary lesion (in the lung) is resolved
These bones are from a dog with a lung tumor. what is the lesion?
hypertrophic osteopathy
What is the synonym for osteochondromas?
multiple cartilaginous exostoses
describe the lesions of osteochondromas?
mass of trabecular bone and cartilage arising from metaphyseal areas of multiple bones
what is the progression of osteochondroma
appear at a young age and increase until growth stops at skeletal maturity
This is a section of a metaphysis from a long bone. Lesions like this appear on multiple bones. what is the pathology?
osteochondroma
what are the most common and clinically important primary bone neoplasias?
- osteosarcoma
- chondrosarcoma
with primary bone neoplasias, diagnosis often requires _____. Clinical ____ and _____ appearance are essential for accurate diagnosis.
biopsy
history
radiographic
osteosarcomas are ____ growing (slow/fast), _____, (aggressive/non-aggressive), and ______ (benign/malignant)
fast growing
aggressive
malignant
what exactly is an osteosarcoma? what is a common ddx for this lesion?
malignant osteoblasts produce bone and destroy existing bone
ddx: osteomyelitis
how does osteosarcoma progress?
local invasion and early pulmonary metastasis
what are the predilection sites for osteosarcomas?
distal radius/ulna, proximal humerus, distal femur, distal/proximal tibia
basically “away from the elbow, towards the knee”
with osteosarcoma, what part of the bone is NOT affected?
joint spaces
osteosarcomas common and rare in what species?
common in dogs/cats, rare in other spp
This is a bone from a dog. The joint space near the lesion is totally fine. What is your primary differential?
osteosarcoma
Fill in the table telling you how to differentiate osteosarcomas from osteomyelitis.
what is a chondrosarcoma?
tumor of malignant chondrocytes that product cartilage (not bone!)
what is the behaviour of a chondrosarcoma?
slow growing, malignant, localized bone destruction
where do chondrosarcomas arise from?
flat bones
in terms of secondary bone neoplasia, which is more common, carcinomas or sarcomas? of the kind that’s more common, what tumor types frequently metastasize into bones?
carcinomas»_space;» sarcomas
carcinomas of mammary gland, lung, prostate
true or false. Secondary bone neoplasia is overdiagnosed in animals.
false. it is probably under diagnosed. animals euthanized before progression, 60% of humans have skeletal metastasis
what is the most common location to find secondary bone neoplasia?
ribs, vertebrae, proximal long bones
Lung-Digit Syndrome:
1. affects who?
2. pathogenesis?
3. why is this significant?
- cats
- pulmonary carcinoma metastasizes to digits –> localized proliferation and spread –> destroys nail bed –> slough claw
- you may detect the digit lesion before the lung neoplasia
You see this lesion on a cat. What should you look for next? What is this most likely?
look at the lungs for neoplasia
this is probably lung-digit syndrome
Lead toxicity leads to what lesion in bones?
lead line – band of sclerosis within the metaphysis of developing bones – visible radiographically
describe the pathogenesis of lead toxicity
lead is toxic to osteoclasts –> impaired remodelling –> metaphyseal osteosclerosis
You see this lesion during necropsy. what should be on the top of your ddx list?
lead toxicity
What is chrondrodysplasia?
hereditary disorders of bone growth due to abnormal growth cartilage
Disproportionate dwarfism is a kind of _____. what is it? which species were highlighted?
chondrodysplasia
short-legged with normal-sized heads
all bones undergoing endochondral ossification will be affected
can affect any species, but the breeds are basset hounds, dachshund, pekingese
What is osteopetrosis? What is the difference between this and osteosclerosis?
osteopetrosis = increased bone density with no medullary cavity
osteosclerosis = increased bone density with medullary cavity
what is the cause of osteopetrosis?
defective osteoclasts fail to resorb bone
osteopetrosis is heritable in which breeds?
Angus cattle
Peruvian Paso horses
Can osteopetrosis be infectious?
yes!
ex. BVD in cattle
This is a long bone from a cattle. What is the lesion?
osteopetrosis
Osteogenesis imperfecta:
1. what is it?
2. pathogenesis?
3. common lesions?
- genetic disease: abnormal type 1 collagen
- reduced trabecular bone –> fxs, joint laxity, and abnormal dentin
- blue sclera, pink teeth due to abnormal dentin
Tell me the differences between these 3 terms: syndactyly, polydactyly, polymelia
syndactyly: partial or complete fusion of digits/phalanges
polydactyly: an increase in the number of digits
polymelia: increase in the number of limbs
Tell me which species each of these are common in:
1. syndacyly
2. polydactyly
- cattle
- dogs, cats, horses, cattle
What is the lesion? (bird feet)
polymelia
what is going on?!
syndactyly
what is going on?
polydactyl cutie pie
what is brachygnathia inferior?
shortening of the mandible (overbite)
what is brachygnathia superior?
shortening of the maxillae (underbite)
think of brachycephalics
what is the lesion?
brachygnathia inferior
what is this lesion?
brachygnathia superior
What is lordosis? what is the common name for this in horses?
abnormal ventral curvature of the spinal column
swayback
What is the lesion?
lordosis
what is kyphosis? what is the common name of this in horses?
abnormal dorsal curvature of the spinal column
roach backs
what is the lesion?
kyphosis
what is scoliosis?
abnormal lateral deviation of the spinal column
what is the lesion?
scoliosis
what is spina bifida? where are the most common locations for this? is this usually a lone defect?
defective closure of the dorsal vertebral lamina in the vertebral column
most common in lumbar and sacral lesions
no, this is often associated with other defects
what is the lesion?
spina bifida
