Final Exam - Joint Disease of the Hip Flashcards
what is the pathogenesis of canine hip dysplasia?
laxity develops during skeletal growth because the soft tissues supporting the hip are unable to develop & keep pace with rapid bone growth - laxity results in subluxation of the hip joint during weight bearing with repetitive luxation resulting in lameness
what is the 2nd most common cause of pelvic limb lameness?
canine hip dysplasia
why is canine hip dysplasia considered to be developmental & not congenital?
hips are normal at birth
T/F: canine hip dysplasia is typically a bilateral disease
true
what factors have been directly implicated in canine hip dysplasia?
breed - common in large/giant breeds (GSD, st bernards, goldens, labs)
diet - maximizes trait expression in genetically susceptible individuals
body weight - obesity
sterilization - OHE/neuter increases risk
activity level - worsens clinical signs associated with disease
maternal factors - increased relaxin, testosterone, estradiol
what is the one phrase that can be used to describe the underlying pathophysiology of CHD?
excessive joint laxity
what is the source of the lameness in early canine hip dysplasia?
activation of pain fibers within the ligament of the femoral head, joint capsule, & labrum - not osteoarthritis
what has occurred in a dog with CHD that has the resolution of clinical signs by 12-18 months of age?
the body responds to excessive joint laxity & attempts to stabilize the joint through fibrosis of the joint capsule & ligament of the femoral head - the fibrosis can be capable of resolving clinical signs but doesn’t mean the patient is cured
what is the bimodal age distribution for dogs with CHD?
young dogs - display clinical signs because of excessive joint laxity, joint subluxation, & soft tissue pain
mature dogs - display clinical signs because of OA that occurs secondary to previous joint laxity
what is the typical history of a young dog with CHD? what about an old dog?
young - bunny hop gait, acute signs, can be identical to CCL ruptures, normal sit test
mature - pet is ‘getting older’, difficulty rising, insidious/slowly progressive
what is an ortolani sign?
physical exam test used to detect joint laxity - one hand is placed on the dorsal aspect of the pelvis for counter pressure
stifle is flexed 90 degrees & cradled with the other hand, hip is put into a weight bearing position & firm pressure is generated by compression hands together, while maintaining pressure - limb is slowly abducted
during early phases of CHD - a palpable/visible click or pop occurs as the femoral head reduces within the acetabulum
T/F: normal puppies can have a positive ortolani sign until approximately 4-6 months of age
true - if present after 6 months of age, suggestive of CHD
why may a mature dog not have a positive ortolani sign?
as OA develops within the hip, acetabular infilling with new bone occurs resulting in loss of a normal acetabular depth - result is a loss of a deep structurally normal acetabulum to allow for reduction of the femoral head
as the body responds to excessive laxity, periarticular fibrosis develops & may limit the examiner from subluxating the femoral head
why are sedated radiographs necessary for a dog with CHD?
to rule out other causes of lameness, confirm the clinical diagnosis, to provide the owner with recommendations regarding breeding, & to classify or stage the patient’s hips (is the dog in early phases of CHD but no OA? has the dog developed OA? radiographic severity?)
what radiographic techniques are commonly used to evaluate & grade CHD?
OFA-style & pennhip
what are the advantages & disadvantages of using OFA-style rads for CHD?
advantages - excellent for identifying OA & helpful in determining phase/stage of CHD
disadvantages - can miss early cases, if submitting for OFA, can’t be graded until 2 years of age
how are pennhip rads taken?
rads of the hip joints are obtained with the hips in a weight bearing position before & during the simulation of weight bearing - measurements are made creating a distracting index where a DI of 0 indicates zero laxity & a DI of 1 indicates complete luxation
if you have a DI <0.3 on pennhip rads, what does that mean? what about a DI of >0.7?
<0.3 - no laxity/subluxation, unlikely to have CHD
> 0.7 - excessive joint laxity/subluxation, likely to have CHD
what is the use of pennhip rads?
used to predict the likelihood of development of future CHD based on an objective measure of laxity - big tool for breeders wanting to make selections before 2 years of age
what are the treatment goals for CHD?
controlling clinical signs, elimination of excessive laxity, & treatment of existing OA
what are the indications for a juvenile pubic symphysiodesis?
young dogs ideally 16-20 weeks of age with clinical signs of CHD, positive ortolani, & must be free of OA
what is the goal of performing a JPS?
correcting excessive joint laxity by improving dorsal acetabular rim coverage of the femoral head during skeletal growth
how is a JPS performed?
small ventral approach is made to the pubic symphysis where it is cauterized resulting in necrosis/growth arrest of this portion of the pelvis - as the puppy grows, the sacrum widens & the remainder of the pelvis grows resulting in lateral rotation of the dorsal acetabular rim
results in improved coverage of the femoral head, improved hip congruity, resolution of laxity/subluxation, & resolution of clinical signs
why must you spay/neuter a dog when a JPS is done?
there will be no evidence of the surgery once maturity is reached & the animal could pass certification for breeding if left intact
