Objective—To determine effects of hip joint osteoarthritis on radiographic measures of hip joint laxity and congruence.
Animals—40 Labrador Retrievers.
Procedures—Dogs were assigned to 2 groups based on radiographic evidence of osteoarthritis. Dogs in the osteoarthritis group were free of osteoarthritis at initial radiographic evaluation (t1) and developed osteoarthritis by a subsequent radiographic evaluation (t2). Dogs in the nonosteoarthritis group had no radiographic osteoarthritis at either evaluation. Hip joint laxity was quantified by use of the distraction index (DI) from a distraction radiographic view and use of the Norberg angle (NA) from a ventrodorsal hip-extended radiographic view. The compression index (CI) from a compression radiographic view was used as a measure of joint congruence (concentricity).
Results—Hip joint laxity (NA or DI) did not change over time in the nonosteoarthritis group. Mean hip joint laxity (NA and DI) for the osteoarthritis group was greater at t1 than for the nonosteoarthritis group. With the onset of osteoarthritis, mean NA decreased significantly and mean CI increased significantly, but mean DI remained unchanged.
Conclusions and Clinical Relevance—No radiographic evidence for compensatory hip joint tightening associated with osteoarthritis was detected. Hip-extended radiography revealed that hip joints got looser with osteoarthritis and NA decreased. Hip joint laxity (DI) on distraction radiographs was unchanged by the onset of osteoarthritis and remained constant in the osteoarthritis and nonosteoarthritis groups at both evaluations. However, the CI increased with osteoarthritis, as reflected in nonzero indices (incongruence). The CI may be a valid marker for early hip joint osteoarthritis.
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;
Objective—To determine prevalence of a radiographic
caudolateral curvilinear osteophyte (CCO) on the
femoral neck in various breeds and age groups of
dogs and to evaluate its contemporaneous relationship
with degenerative joint disease (DJD) and distraction
Design—Cross-sectional prevalence study.
Animals—25,968 dogs, including 3,729 German
Shepherd Dogs, 4,545 Golden Retrievers, 6,277
Labrador Retrievers, and 1,191 Rottweilers.
Procedure—Data from the University of
Pennsylvania Hip Improvement Program database
were analyzed, including ventrodorsal hip-extended,
compression, and distraction radiographs. The CCO
and radiographic signs of DJD were considered independent
events and were interpreted as either present
or absent. Statistical methods were used to evaluate
the CCO as a possible risk factor for DJD and
assess its association with DI, as measured by use of
Results—When all breeds were pooled, DJD was
detected in 8.6% of dogs, and the CCO was detected
in 21.6% of dogs. Among dogs with a CCO,
25.1% had radiographic evidence of DJD. Among
dogs without a CCO, only 4% had DJD. Dogs with a
CCO were 7.9 times as likely to have DJD as were
those without a CCO. Additionally, DI, weight, and
age were significant risk factors for the CCO.
Conclusion and Clinical Relevance—Results confirm
the contemporaneous association between the
CCO and DJD and that passive hip laxity, as measured
by use of the DI, is associated with both the CCO and
DJD. (J Am Vet Med Assoc 2002;220:472–476)
Objective—To determine whether age, breed, sex,
weight, or distraction index (DI) was associated with
the risk that dogs of 4 common breeds (German
Shepherd Dog, Golden Retriever, Labrador Retriever,
Rottweiler) would have radiographic evidence of
degenerative joint disease (DJD) associated with hip
Design—Cross-sectional prevalence study.
Procedure—Hips of dogs were evaluated radiographically
by use of the ventrodorsal hip-extended view, the compression view, and the distraction view. The ventrodorsal hip-extended view was examined to determine whether dogs had DJD. For each breed, a multiple logistic regression model incorporating age, sex, weight, and DI was created. For each breed, disease-susceptibility curves were produced, using all
dogs, regardless of age, and dogs grouped on the basis of age.
Results—Weight and DI were significant risk factors
for DJD in all breeds. For German Shepherd Dogs, the
risk of having DJD was 4.95 times the risk for dogs of
the other 3 breeds combined. In all breeds, the probability
of having DJD increased with age.
Conclusions and Clinical Relevance—Results indicated
that the probability of having hip DJD increased
with hip joint laxity as measured by use of DI. This
association was breed-specific, indicating that breedspecific
information on disease susceptibility should be
incorporated when making breeding decisions and
when deciding on possible surgical treatment of hip
dysplasia. (J Am Vet Med Assoc 2001;219:1719–1724)
Objective—To evaluate the effects of diet restriction on development of radiographic evidence of hip joint osteoarthritis in dogs.
Design—Longitudinal cohort study.
Animals—48 Labrador Retrievers from 7 litters.
Procedures—Forty-eight 6-week-old puppies from 7 litters were paired with littermates by sex and weight, and each pairmate was randomly assigned to 1 of 2 groups of 24 dogs each. Starting at 8 weeks of age, 1 group was fed ad libitum (control fed) and the other was fed 25% less (restricted fed) of the same diet for life on a pairwise basis. The dogs' hip joints were radiographed in the standard ventrodorsal hip-extended view at multiple intervals prior to 1 year of age and at annual intervals thereafter on the basis of birth anniversary. A board-certified radiologist unaware of group assignment scored the radiographs for evidence of osteoarthritis.
Results—Prevalence of radiographic evidence of hip joint osteoarthritis in all dogs increased linearly throughout the study, from an overall prevalence of 15% at 2 years to 67% by 14 years. Restricted-fed dogs had lower prevalence and later onset of hip joint osteoarthritis. Median age at first identification of radiographic evidence of hip joint osteoarthritis was significantly lower in the control-fed group (6 years), compared with the restricted-fed group (12 years).
Conclusions and Clinical Relevance—Restricted feeding delayed or prevented development of radiographic signs of hip joint osteoarthritis in this cohort of Labrador Retrievers. Lifetime maintenance of 25% diet restriction delayed onset and reduced severity of hip joint osteoarthritis, thus favorably affecting both duration and quality of life. In addition, the data indicated that development of hip joint osteoarthritis was not bimodal in these dogs but occurred as a continuum throughout life.
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.