Objective—To compare 2 screening methods for detecting evidence of hip dysplasia (Orthopedic Foundation for Animals [OFA] and PennHIP) in dogs.
Design—Diagnostic test evaluation study.
Animals—439 dogs ≥ 24 months of age that received routine hip joint screening from June 1987 through July 2008.
Procedures—Dogs were sedated, and PennHIP radiography was performed (hip joint– extended [HE], compression, and distraction radiographic views). The HE radiographic view was submitted for OFA evaluation. A copy of the HE radiographic view plus the compression and distraction radiographic views were submitted for routine PennHIP evaluation, including quantification of hip joint laxity via the distraction index (DI).
Results—14% (60/439) of dogs had hip joints scored as excellent by OFA standards; however, 52% (31/60) of those had a DI ≥ 0.30 (range, 0.14 to 0.61). Eighty-two percent of (183/223) dogs with OFA-rated good hip joints had a DI ≥ 0.30 (range, 0.10 to 0.77), and 94% (79/84) of dogs with OFA-rated fair hip joints had a DI ≥ 0.30 (range, 0.14 to 0.77). Of all dogs with fair to excellent hip joints by OFA standards, 80% (293/367) had a DI ≥ 0.30. All dogs with OFA-rated borderline hip joints or mild, moderate, or severe hip dysplasia had a DI ≥ 0.30 (range, 0.30 to 0.83).
Conclusion and Clinical Relevance—Dogs judged as phenotypically normal by the OFA harbored clinically important passive hip joint laxity as determined via distraction radiography. Results suggested that OFA scoring of HE radiographs underestimated susceptibility to osteoarthritis in dogs, which may impede progress in reducing or eliminating hip dysplasia through breeding.
Objective—To evaluate hip joint laxity in 10 breeds of
dogs via 2 radiographic techniques.
Animals—500 clinically normal dogs.
Procedure—Radiographs obtained via routine hip
joint evaluations performed in sedated dogs of 10
popular breeds were randomly selected from a database.
Measurements of distraction index (DI) and hipextended
index (HEI) on 1 hip joint radiograph randomly
chosen from each dog were made.
Results—Mean age of dogs was 20.7 months.
Mean HEI was 0.17 (range, 0.0 to 0.72) and mean
DI was 0.44 (range, 0.07 to 0.96). Borzois had uniformly
tight hip joints as judged by use of both
methods and were considered the gold standard by
which hip joint laxity was judged (all Borzois had DI
≤ 0.32). Overall, DI was significantly greater than
HEI. Within each breed, mean DI was always
greater than mean HEI. Significant differences were
detected among breeds for HEI; however, compared
with DI, the magnitude of differences among
breeds was less.
Conclusions and Clinical Relevance—Distraction
radiography detected the greatest range and magnitude
of passive hip laxity in the 10 breeds of dogs. The
difference in values between breeds known to have
high prevalence of canine hip dysplasia and those in
Borzois was greater for DI than for HEI. Breeds must
be evaluated individually because of inherent differences
in hip joint laxity. ( J Am Vet Med Assoc 2004;