Evaluation of the relationship between Orthopedic Foundation for Animals' hip joint scores and PennHIP distraction index values in dogs.
OBJECTIVE
To compare 2 screening methods for detecting evidence of hip dysplasia (Orthopedic Foundation for Animals [OFA] and PennHIP) in dogs.


METHODS
Diagnostic test evaluation study. Animals-439 dogs >or= 24 months of age that received routine hip joint screening from June 1987 through July 2008.


METHODS
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 >or= 0.30 (range, 0.14 to 0.61). Eighty-two percent of (183/223) dogs with OFA-rated good hip joints had a DI >or= 0.30 (range, 0.10 to 0.77), and 94% (79/84) of dogs with OFA-rated fair hip joints had a DI >or= 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 >or= 0.30. All dogs with OFA-rated borderline hip joints or mild, moderate, or severe hip dysplasia had a DI >or= 0.30 (range, 0.30 to 0.83).


CONCLUSIONS
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.
Powers
Michelle Y
MY
Department of Clinical Studies-Philadelphia, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
Karbe
Georga T
GT
Gregor
Thomas P
TP
McKelvie
Pamela
P
Culp
William T N
WT
Fordyce
Hilary H
HH
Smith
Gail K
GK
D000818:Animals; D004283:Dog Diseases / Q000145:classification / Q000000981:diagnostic imaging*; D004285:Dogs; D006619:Hip Dysplasia, Canine / Q000145:classification / Q000000981:diagnostic imaging*; D007593:Joint Instability / Q000145:classification / Q000000981:diagnostic imaging / Q000662:veterinary; D009985:Orthopedics / Q000458:organization & administration / Q000592:standards / Q000662:veterinary; D011859:Radiography / Q000592:standards / Q000662:veterinary; D014481:United States