Lecture 29: MSK 2 Flashcards
What is fluorosis? What are the gross lesions and why do they develop?
Chronic and severe fluoride toxicity
- mainly cattle (also sheep/horse)
Impairs normal bone metabolism in developing teeth - no impact on mature teeth
- ameloblacsts and odontoblasts are sensitive to excess fluoride
causes
- odontodystrophy (thin/no enamal and dentine) = increased wear to the teeth
- osteofluorosis = periosteal hyperostosis
- lameness = digital/claw fractures
You suspect fluorosis in a mature cow. Dou you also expect associated digital fractures?
No
exposure in older animals causes bone pathology only
What is a primary lesion of lead toxicity and why does it occur?
lead lines
- growth retardation lattice/growth arrest line
- metaphyseal sclerosis
toxic impairment of osteoclasts
- impair remodelling of trabecullae
What is the impact of vitA toxicity on bone? What is a common signalment?
cats being fed high liver diet
causes physeal damage and osteoporosis
can result in exostosis (nodules) from chronic exposure
= deforming cervical spondylosis in cats over 2yo
Describe the primary mechanism for vitamin D toxicity in SA and LA respectively
rodenticide
calcinogenic plants
What is the most important gross lesion of vitD toxicity? How does that differ from the other lesions that can form?
mainly metastatic mineralization in soft tissue after an acute exposure
after chronic exposure skeletal lesions form
- early it is high osteoclast activity (reduce primary spongiosa)
- later increased osteoblast activity (deposition of abnormal matrix)
What is verratum californicum
a plant
steroidal alkaloid
affecting grazing animals
- sheep at 14d gestation = fetus with cyclopia
Define osteitis
inflam of bane
Define osteomyelitis
inflam of bone and the medulla
Define periosteitis
inflam of periosteum
What are 3 main routes of entry to the bone
direct - wound or fracture
direct extension from adjacent tissue
- periodontitis
- otitis media
hematogenous - most important
Where does hematogeous spread bone inflammation localize and why?
in the metaphysis
because…
- capillary/hairpin loops
- fenetrated endothelium
- slow blood flow
predispose to infection
In what animals is hematogenous infection most common?
young (especially farm animals)
because the physis has no blood supply
- if there is no blood supply then there is no immune protection
What are 2 common sequelae of bone inflammation and why?
necrosis leading to sequestrun and involucrum
exudate and edema lead to ischemia = infarct
What causes bacterial osteomyelitis and what is the main consequence
anything that can get into the blood
causing bone necrosis
What is the causative agent of lumpy jaw? What is the gross lesions and what type of injury does it cause?
Actinomyces bovis
causes honeycomb appearance on cut surface due to bone resorption and necrosis
causing pyogranulomatous osteomyelitis
How is fungal osteomyelitis spread? What general category of fungi causes fungal osteomyelitis?
hematogenous
dimorphic
What are the clinical consequences of fungal osteomyelitis?
causing pyogranulomatous - granulomatous inflammation leading to sequestrun and involucrum
bone lysis
periosteal reaction
pathological fractures
What gross lesion is viral osteomyelitis associated with? What are some examples of causative agents?
growth retardation lattices due to viral destruction of osteoclasts
BVBV (cow)/CSF(pig)/border dz (sheep)/distemper(dog)
What is metaphyseal osteopathy?
It is an idiopathic and self limiting condition
affects distal radius and ulna (long bones)
suppurative and fibrous osteomyelitis
What is the common signalment for an animal with metaphyseal osteomyelitis? What is a good diagnostic tool?
young large breed dogs
radiographs - shaw a ‘double physis’
What is the common signalment for an animal with panosteitis? What are the clinical and radiographic signs?
young large breed dogs (GSD)
causes shifting lameness without inflammation
radiographs:
- expanding foci of fibrovascular tissue
- woven bone
- maturation and resorption
- periosteal reaction
What is legge-calve perthes disease? What animals does it affect? What is the main clinical consequence?
avascular femoral head necrosis due to a delay or occlusion in vascular development
young small breed dogs
cause collapse of necrotic bone and stretching or rupture of the capital ligaments
Define hyperostosis
excessive bone formation
List 3 types of hyperostotic disease
craniomandibular osteopathy
hypertrophic osteopathy
osteochondroma
What is craniomandibular osteopathy? What animals does it affect?
It is the hyperostosis of the skull bones (mandible/occipital/temporal)
westies 4-7mo
aka lion jaw
What is hypertrophic osteopathy? How do you treat it?
increased bone production on the periosteum
associated with space occupying lung masses (chronic inflammation or neoplasia)
can resolve if the space occupying thorax mass is removed
What is an osteochrondroma? What animals does it affect?
It is a benign and incidental exostosis (nodule of periosteal bone) development
- grows from the physis and is capped by cartilage
- it will stop growing when the skeleton matures
young and growing dogs and horses
What is the classification of primary bone neoplasias
mesenchymal (sarcomas if malignant)
How does the prognosis of primary bone neoplasms differ between species
cow/horse = mainly benign
dog = mainly malignant
cat = 50/50
What are the most prominent characteristics of an osteoma? What species is commonly affected?
horses
cranio-facial bone
slow growing and benign
non painful
What are 2 other differential diagnoses you should think of then considering osteoma
ossifying fibroma
fibrous dysplasia
What are most prominent characteristics of an osteosarcoma? What animals are commonly affected?
most common primary bone tumor in dogs and cats
affect mainly appendicular skeleton (away from elbow and toward the knee)
do not cross joint spaces
make osteoid
metastasize early to lungs
How are primary bone tumors classified?
peripheral - periosteum
- periosteal: from cambrium layer of periosteum
- parosteal: from fibrous layer of periosteum
central - endosteum
What is the most common type of osteosarcoma? What are the features of this neoplasia?
central
it is very progressive
metastasized early to the lungs
doesn’t cross joint spaces
Malignant osteoblasts make osteoid
creates a starburst pattern on radiograph
Compare chondroma and chondrosarcoma
chondroma
- rare (dog and sheep mainly)
- flat bones
- benign
chondrosarcoma
- cat/dog/sheep
- central or peripheral
- malignant
Compare chondrosarcoma and osteosarcoma
chondrosarcoma
- can cross joint spaces
- make chondroid matrix (looks like hyaline cartilage)
osteosarcoma
- can’t cross joint spaces
- make osteoid
What are the typical gross bone lesions associated with lymphoma?
mottles and infarcted yellow bone
List 4 other primary bone tumors
- multilobar
- fibrosarcoma
- liposarcoma
- plasma cell myeloma
What are the common features of a secondary bone neoplasia? Give an example
spread via hematogenous or direct extension
carcinoma
lung-digit syndrome (feline pulmonary adenocarcinoma)
A cat presents to you with masses on its digits. What is a primary diagnosis? What would be a useful diagnostic?
feline pulmonary adenocarcinoma leading to lung-digit syndrome
thoracic radiographs
Differentiate congenital and genetic diseases
congenital: it was present at birth
- may or may not be genetic
genetic: hereditary
What is congenital hyperostosis? What animal does it affect mainly? What causes it?
It is the thickening (due to periosteal reaction on diaphysis) of front limbs
newborn pigs
unknown cause (maybe abnormal positioning in utero)
List 4 genetic bone diseases
chondrodysplasia
osteopetrosis
osteogenesis imperfecta
spina bifida
What is chondrodysplasia? What is the main consequence?
generalized cartilage defects preferentially affecting the appendicular skeleton (bones made by endochondral ossification)
disproportionate dwarfism
List 5 clinical manifestations of chondrodysplasia
texel chondrydysplasia - sheep
spider lamb syndrome - suffolk and Hampshire sheep
snorter dwarfism - brachycephalic herford and angus cows
lethal bulldog - calves (aborted)
breed standards: corgi/daschund/scottish fold
What is osteopetrosis? What animals does it affect?
cattle and horses
increased bone density in the metaphysis and diaphysis due to defective osteoclasts
- no resorption = accumulation of primary spongiosa
a normal physis is maintained
What are the sequelae of osteopetrosis?
pathologic fractures
aplastic anemia
thrombocytopenia
What is osteogenesis imperfecta? What are the gross lesions?
type 1 collagen defect
- rare
cause fragile/thin/brittle bone
blue areas on the sclera and fragile/pink teeth
Compare brachygnathia inferior and superior
inferior: abnormally small mandible
superior: abnormally small maxilla
Define amelia
no limbs
Define hemimelia
no distal limbs
Define phocomelia
no proximal limbs
Define polymelia
extra limbs
Define micromelia
too short limbs
Define syndactyly
fusion of digits
Define polydactyly
extra digits
Define lordosis
ventral deviation of the spine
Define kyphosis
dorsal deviation of the spine
Define scoliosis
lateral deviation of the spine
Define kyphoscoliosis
dorso-lateral deviation of the spine
What is spina bifida
Absence of the dorsal spinal vertebrae - exposed spinal cord
