title: Use of the ventrodorsal myelographic view to predict lateralization of extruded disk material in small-breed dogs with thoracolumbar intervertebral disk extrusion: 104 cases (2004-2005).
abstract: OBJECTIVE
  To determine whether the ventrodorsal myelographic view can be used to accurately predict the circumferential location of extruded disk material in dogs with thoracolumbar intervertebral disk extrusion (IVDE) and to describe paradoxical contrast obstruction (PCO).
  
  
  METHODS
  Retrospective case series.
  
  
  METHODS
  104 dogs with Hansen type I IVDE. Procedures-Ventrodorsal myelographic views were reviewed, and contrast patterns were categorized according to 8 predetermined patterns. Agreement among observers was compared, and the predicted location of extruded disk material was compared with surgical findings.
  
  
  RESULTS
  Agreement regarding myelographic pattern and location of extruded disk material was moderate (kappa = 0.74 and 0.80, respectively) among the 4 observers. Ninety-three (89%) dogs had myelographic evidence of lateralized extrusion, and in 83 of the 93 (89%), predicted location of extruded disk material matched the surgically confirmed location. In 33 of the 40 (83%) dogs with bilateral contrast column gaps of unequal length, disk material was found to be located on the side with the shorter, rather than the longer, contrast gap, a phenomenon described as PCO.
  
  
  CONCLUSIONS
  Results suggested that the ventrodorsal myelographic view could be used to predict the circumferential location of extruded disk material in dogs with thoracolumbar IVDE more often than previously reported. The PCO phenomenon may be useful in determining the side of lateralization when contrast material does not outline the extruded disk material.
authors.affiliation: Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, ON N1G 2W1, Canada.
authors.forename: Alexandra Squires
authors.initials: AS
authors.lastname: Bos
authors.forename: Brigitte A
authors.initials: BA
authors.lastname: Brisson
authors.forename: David L
authors.initials: DL
authors.lastname: Holmberg
authors.forename: Stephanie G
authors.initials: SG
authors.lastname: Nykamp
mesh_terms: D000818:Animals; D003937:Diagnosis, Differential; D004283:Dog Diseases / Q000000981:diagnostic imaging* / Q000601:surgery; D004285:Dogs; D005260:Female; D007403:Intervertebral Disc; D007405:Intervertebral Disc Displacement / Q000000981:diagnostic imaging / Q000601:surgery / Q000662:veterinary*; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging* / Q000601:surgery; D008297:Male; D009192:Myelography / Q000379:methods / Q000662:veterinary*; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013116:Spinal Cord / Q000000981:diagnostic imaging / Q000601:surgery; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging* / Q000601:surgery