title: Reliability of the hip distraction index in two-month-old German shepherd dogs.
abstract: OBJECTIVE
  To determine whether distraction index (DI), a measure of passive hip joint laxity, at 2 months of age was predictive of DI at 4 or 12 months of age in German Shepherd Dogs.
  
  
  METHODS
  Prospective cohort study.
  
  
  METHODS
  45 German Shepherd Dogs.
  
  
  METHODS
  DI was measured at 2, 4, and 12 months of age. At the same times, a standard ventrodorsal radiographic projection of the pelvis with the hip joints extended was obtained and examined for evidence of degenerative joint disease (DJD). To facilitate radiographic positioning, dogs were sedated or anesthetized.
  
  
  RESULTS
  DI at 2 months of age was not significantly correlated with DI at 4 or 12 months of age. However, DI at 4 months of age was correlated with DI at 12 months of age. The proportion of dogs with DI > or = 0.3 at 12 months of age that had radiographic evidence of DJD by 12 months of age (13/22; 59%) was significantly greater than the proportion of dogs with DI < 0.3 at 12 months of age that had radiographic evidence of DJD by 12 months of age (1/9; 11%).
  
  
  CONCLUSIONS
  For German Shepherd Dogs, DI at 2 months of age was not sufficiently reliable to predict DI at 4 and 12 months of age; however, DI at 4 and 12 months of age were comparable. We recommend that, for German Shepherd Dogs, DI not be measured before 4 months of age and that particularly for breeding dogs, DI be remeasured after maturity to confirm DI obtained at earlier ages. Studies including other breeds of dogs should be done to determine the youngest reliable age to initiate hip joint screening.
authors.affiliation: Department of Clinical Studies, School of Veterinary Medicine, University of Pennsylvania, Philadelphia 19104-6010, USA.
authors.forename: G K
authors.initials: GK
authors.lastname: Smith
authors.forename: C M
authors.initials: CM
authors.lastname: Hill
authors.forename: T P
authors.initials: TP
authors.lastname: Gregor
authors.forename: K
authors.initials: K
authors.lastname: Olson
mesh_terms: D000367:Age Factors; D000704:Analysis of Variance; D000818:Animals; D001947:Breeding; D015331:Cohort Studies; D004283:Dog Diseases / Q000175:diagnosis* / Q000453:epidemiology / Q000473:pathology; D004285:Dogs; D005260:Female; D005500:Follow-Up Studies; D006619:Hip Dysplasia, Canine / Q000175:diagnosis* / Q000453:epidemiology / Q000473:pathology; D006621:Hip Joint / Q000473:pathology* / Q000502:physiology; D007593:Joint Instability / Q000175:diagnosis / Q000473:pathology / Q000662:veterinary*; D008297:Male; D011237:Predictive Value of Tests; D011446:Prospective Studies; D015203:Reproducibility of Results