title: The vacuum phenomenon in intervertebral disc disease of dogs based on computed tomography images.
abstract: OBJECTIVE
  Vacuum phenomenon is suspected to be indicative of disc degeneration and subsequent herniation. The objective of this study was to assess the reliability of vacuum phenomenon for identification of herniated discs causing neurological signs. Prevalence of vacuum phenomenon and influencing factors in dogs with disc herniation were determined.
  
  
  METHODS
  Retrospective review of computed tomography scans from dogs with suspected disc herniation for the presence of gas within intervertebral disc space with subsequent comparison of vacuum phenomenon and herniated disc as confirmed by surgery. Subgroups were created (chondrodystrophic, non-chondrodystrophic and unknown classification) to analyse prevalence and influencing factors (age, breed and gender) for vacuum phenomenon and agreement with herniated disc.
  
  
  RESULTS
  Prevalence of vacuum phenomenon in all dogs, chondrodystrophic, non-chondrodystrophic dogs and those with unknown classification was 19·8, 14·9, 35·7 and 24·5%, respectively. Corresponding correlation rate between vacuum phenomenon and herniated disc was 64, 67, 40 and 82%. Prevalence of vacuum phenomenon was significantly higher in nonchondrodystrophic dogs (P=0·04). Age was the only factor influencing prevalence of vacuum phenomenon (P=0·04).
  
  
  CONCLUSIONS
  In dogs with intervertebral disc disease, vacuum phenomenon is a frequent but inconsistent finding. Although helpful to identify degenerated discs, it is not suitable to identify currently herniated disc with sufficient accuracy.
authors.affiliation: Department of Small Animal Medicine, University of Leipzig, An den Tierkliniken 23, 04103, Leipzig, Germany.
authors.forename: M K
authors.initials: MK
authors.lastname: Müller
authors.forename: E
authors.initials: E
authors.lastname: Ludewig
authors.forename: G
authors.initials: G
authors.lastname: Oechtering
authors.forename: M
authors.initials: M
authors.lastname: Scholz
authors.forename: T
authors.initials: T
authors.lastname: Flegel
mesh_terms: D000818:Animals; D004283:Dog Diseases / Q000175:diagnosis* / Q000473:pathology; D004285:Dogs; D007405:Intervertebral Disc Displacement / Q000175:diagnosis / Q000473:pathology / Q000662:veterinary*; D015995:Prevalence; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000592:standards / Q000662:veterinary*; D014618:Vacuum