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
what horse breeds are associated with developmental subchondral bone cysts? what age?
american quarter horses, arabians, & thoroughbreds
18 months to 3 years of age
what clinical signs may be seen with subchondral bone cysts?
increased bilateral lameness with exercise (grade 2-3/5) that is intermittent & gets better with rest
effusion isn’t consistent
may see good improvement with nerve blocks
where is the common location of a subchondral bone cyst at the femoropatellar joint?
medial femoral condyle
where is the common location of a subchondral bone cyst at the mc/mt phalangeal joint?
medial mc/mt 3 condyle
where is the common location of a subchondral bone cyst at the interphalangeal joints?
P1 & P3
where is the common location of a subchondral bone cyst at the humeroradial joint?
medial radial head
what is the most common location for a subchondral bone cyst?
at the femoropateller joint on the medial femoral condyle
what condition is shown here?
subchondral bone cyst
why are subchondral bone cysts often seen bilaterally?
the phase of vulnerability is the occurring at the same time
how are subchondral bone cysts diagnosed?
rads - take them of both legs
when may conservative therapy be indicated for subchondral bone cysts?
it is a central/small lesion - do rest & intraarticular therapy of adequan/steroids/hyaluranon
what locations may arthroscopic procedures be used to correct subchondral bone cysts?
medial femoral condyle & distal metacarpal condyle
what locations may extra-articular procedures be used to correct subchondral bone cysts?
proximal radius & phalanges
why is surgery a good choice for treating subchondral bone cysts?
you’re getting rid of the cytokine source resulting in inflammation & correcting instability
most common sx procedure - trans-cystic screw
what clinical signs are consistent with a horse with physeal dysplasia?
physeal enlargement
lameness with exercise
pressure sensitive
+/- deformity (varus)
what is seen on radiographs that is supportive of physeal dysplasia?
irregular physis, metaphyseal flaring, lysis/sclerosis, & +/- deformity
what anatomic location is physeal dysplasia commonly seen in horses?
distal radius & cannon bones
what palliative management is used for physeal dysplasia in horses?
controlled exercise - don’t exercise them too much
NSAIDS
nutrition - balanced structural CHO/reduced feeding to slow growth
what are some complications of physeal dysplasia?
angular deformity - GPR
flexural deformity - desmotomy
what lesion is seen here?
subchondral bone cysts
