title: Estimates of prevalence of hip dysplasia in Golden Retrievers and Rottweilers and the influence of bias on published prevalence figures.
abstract: OBJECTIVE
  To estimate prevalence of canine hip dysplasia (CHD) in Golden Retrievers and Rottweilers and identify sources of bias in published reports.
  
  
  METHODS
  Prospective study.
  
  
  METHODS
  200 clinically normal Golden Retrievers and 140 clinically normal Rottweilers between 24 and 60 months of age referred for hip evaluation (group 1) and 93 clinically normal dogs evaluated for Orthopedic Foundation for Animals (OFA) hip certification (group 2).
  
  
  METHODS
  Hip-extended pelvic radiographs from group 1 dogs were screened for CHD. Radiographs were evaluated twice; the first interpretation used an OFA-type subjective 7-point scoring system, and the second included the caudolateral curvilinear osteophyte as an additional sign of degenerative joint disease. The OFA submission rate of group 2 dogs was determined from the number of official reports returned from the OFA.
  
  
  RESULTS
  Prevalence of CHD in Golden Retrievers ranged from 53% to 73% and in Rottweilers ranged from 41% to 69%. Among dogs referred for OFA evaluation, radiographs from 49 (53%) were submitted to OFA. Of submitted radiographs, 45 (92%) were normal; of radiographs not submitted, 22 (50%) were normal. Radiographs with normal-appearing hips were 8.2 times as likely to be submitted to the OFA. Compared with Golden Retrievers, Rottweiler radiographs were significantly more likely to be submitted for OFA certification.
  
  
  CONCLUSIONS
  Prevalence of CHD in these 2 breeds may be much higher than previously reported in the United States. Results suggest substantial bias in the OFA database, which causes lower estimates of prevalence of CHD.
authors.affiliation: Department of Clinical Studies, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104-6010, USA.
authors.forename: Erin R
authors.initials: ER
authors.lastname: Paster
authors.forename: Elizabeth
authors.initials: E
authors.lastname: LaFond
authors.forename: Darryl N
authors.initials: DN
authors.lastname: Biery
authors.forename: Alisa
authors.initials: A
authors.lastname: Iriye
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Gregor
authors.forename: Frances S
authors.initials: FS
authors.lastname: Shofer
authors.forename: Gail K
authors.initials: GK
authors.lastname: Smith
mesh_terms: D000818:Animals; D001947:Breeding; D004285:Dogs / Q000033:anatomy & histology*; D005260:Female; D020022:Genetic Predisposition to Disease; D006619:Hip Dysplasia, Canine / Q000453:epidemiology* / Q000235:genetics; D006621:Hip Joint / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D008297:Male; D015995:Prevalence; D011446:Prospective Studies; D011859:Radiography; D012307:Risk Factors; D014481:United States / Q000453:epidemiology