Exam 1 - Equine Developmental Bone Disease Flashcards
what growth plate is responsible for longitudinal bone growth in long bones?
metaphyseal growth plate
why does osteochondrosis occur?
ossification of the bone is disrupted resulting in failure of vascularization & cartilage retention
what components act on the retained cartilage resulting in OCD & sub-chondral bone cysts?
shear forces - OCD
compressive forces - bone cysts
what are some causative factors of osteochondrosis in horses?
size/growth rate
nutrition - not properly balanced diets
hereditary
cartilage canals
biomechanical factors
T/F: there can be a breed dependent component for OCD in horses
true - standardbred horses & OCD in the distal tibia
how do the cartilage canals play a role in the development of osteochondrosis?
there is no blood or nerve supply apart from the cartilage canals
failure of vascularization leads to necrosis
what clinical signs are seen with OCD in horses?
history, effusion is the most common & consistent sign
lameness may be variable
will see in immature/growing horses
what joints are commonly affected by OCD in horses?
effusion is consistent in:
femoropatellar, tarsocrural, mc/mt-phalangeal joints
T/F: with OCD in horses, you will usually see it bilaterally
true
what may be seen on a joint fluid cytology of a horse with OCD?
effusion is likely watery with mild inflammation
normal synovial fluid
what does cytology of a normal joint entail?
high viscosity - good mucin clot & stringy pull
nucleated cells <500/uL
mostly mononuclear cells - synoviocytes & few small lymphocytes
what cytology of a joint indicates sepsis?
marked elevations of WBC, >15,000/uL
what values are consistent with inflammation when looking at synovial fluid cytology?
mild elevations from 1,000-10,000 WBC
can see with trauma, DJD, degenerative disorders, & some infectious processes
what may be seen on rads that is indicative of OCD?
subchondral bone defect, sclerosis, & +/- bony fragment
BILATERALLY
where is OCD commonly seen in the femoropatellar joint?
lateral trochlear ridge & patella
where is OCD commonly seen in the tarsocrural joint?
distal intermediate ridge of the tibia & lateral trochlear ridge of the tarsus
where is OCD commonly seen in the metacarpophalangeal joint?
sagittal ridge of the fetlock
where is OCD commonly seen in the glenohumeral joint?
glenoid or humeral head
why is conservative management of OCD in a horse a bad idea?
leaving the bony fragment will cause OA & more permanent changes
why is surgery done on a horse with OCD in the stifle when they are at least 1 year of age?
lets the animal mature more in the stifle
when may conservative treatment be pursued in a horse with OCD?
it is in the stifle or fetlock, (stifle patient is <1 year old), & there is NO FRAGMENT
what is the best treatment for OCD in horses?
surgical removal of the bony fragment
when is a subchondral bone cyst a developmental problem?
there is a disruption in the animal’s normal development resulting in the lesion
how may a horse with normal bone development get a subchondral bone cyst?
it has cartilage or subchondral bone trauma
