Small Animal Radiology and Ultrasound: A Diagnostic Atlas and Text

562 Small Animal Radiolo g y and Ultrasono graphy
A
B
Fig. 4-113 A 1-year-old female Rottweiler was brought in for routine pelvic evaluation. A, In the
pelvic radiographs obtained at 1 year of age, there is mild subluxation of both coxofemoral joints.
Less than 50% of the femoral heads are within their respective acetabula. There is widening of the
coxofemoral joint space, especially at its medial aspect (closed arrows). There is a faint radiodense line
on the right femoral neck (open arrow). This is indicative of mild degenerative joint disease with bony
proliferation at the site of joint capsule attachment. B, The pelvic radiographs were repeated when
the dog was 2 years of age. The degree of subluxation of the coxofemoral joint remains unchanged.
There is poor congruity between the femoral heads and their respective acetabula. The craniodorsal
acetabular margins are flattened. The bony proliferation on the right femoral neck has increased.
Diagnosis: Progressive osteoarthritis secondary to mild bilateral canine hip dysplasia.
(OFA) has recommended that bitches not be radiographed for evaluation during oestrus, a
study that radiographically followed apparent hip joint conformation during oestrus failed to
demonstrate a difference in appearance during the various stages of oestrus. 490
The OFA has served as a referral service for certification of the pelvic conformation of
dogs since 1966. 491 The OFA’s minimal age requirement for certification is 24 months,
because examination prior to that age has a significant chance of producing false-negative
results. In one study, only 10% of dogs with hip dysplasia had radiographic signs at 4
months of age, 15% to 30% at 6 months of age, approximately 70% at 12 months of age,
and approximately 95% at 24 months of age. 492 The same study showed that waiting until
36 months of age increased the diagnostic rate to only 97%. Therefore an evaluation before