title: Determination of Porto-Azygos Shunt Anatomy in Dogs by Computed Tomography Angiography.
abstract: OBJECTIVE
  To describe the morphology of porto-azygos shunts in a large series of dogs using computed tomography (CT) angiography.
  
  
  METHODS
  Retrospective study.
  
  
  METHODS
  Dogs (n=36) with porto-azygos shunts.
  
  
  METHODS
  CT angiography was performed in dogs subsequently proven to have a porto-azygos shunt. The origin and insertion of the shunts were assessed on native images. The diameter of the porto-azygos shunt and the portal vein, cranial and caudal to the shunt origin, were measured. The porto-azygos shunt anatomy was studied on three-dimensional images.
  
  
  RESULTS
  All porto-azygos shunts originated either in the left gastric vein (33 left gastro-azygos shunts) or the right gastric vein (3 right gastro-azygos shunts). Two left gastro-azygos shunts had concurrent caval-azygos continuation and 2 right gastro-azygos shunts had a caudal splenic loop. All shunts crossed the diaphragm through the esophageal hiatus. The majority of porto-azygos shunts (32) followed a straight pathway after traversing the diaphragm, although 4 shunts followed a tortuous route. All shunts terminated in the thoracic part of the azygos vein, perpendicular to the aorta. The shunt diameter at insertion was only 3 mm on average. The insertion site was consistently the narrowest part of the shunt.
  
  
  CONCLUSIONS
  CT angiography was well suited to provide anatomic details of porto-azygos shunts and comprehensively documented that all porto-azygos shunts had a thoracic terminus, after crossing the diaphragm through the esophageal hiatus. Different shunt types existed with minor variations.
authors.affiliation: Department of Small Animal Medicine and Clinical Biology, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium. matanor5@gmail.com.
authors.forename: Matan
authors.identifier: http://orcid.org/0000-0003-3723-0849
authors.initials: M
authors.lastname: Or
authors.affiliation: Laboratory of Veterinary Surgery, Department of Veterinary Medicine, College of Bioresource Sciences, Nihon University, Kanagawa, Japan.
authors.forename: Kumiko
authors.initials: K
authors.lastname: Ishigaki
authors.affiliation: Department of Small Animal Medicine and Clinical Biology, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium.
authors.forename: Hilde
authors.initials: H
authors.lastname: de Rooster
authors.affiliation: Laboratory of Veterinary Surgery, Department of Veterinary Medicine, College of Bioresource Sciences, Nihon University, Kanagawa, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Kutara
authors.affiliation: Laboratory of Veterinary Surgery, Department of Veterinary Medicine, College of Bioresource Sciences, Nihon University, Kanagawa, Japan.
authors.forename: Kazushi
authors.initials: K
authors.lastname: Asano
mesh_terms: D000818:Animals; D001401:Azygos Vein / Q000002:abnormalities* / Q000601:surgery; D000072226:Computed Tomography Angiography / Q000662:veterinary; D004283:Dog Diseases / Q000151:congenital* / Q000473:pathology / Q000601:surgery; D004285:Dogs; D021621:Imaging, Three-Dimensional / Q000662:veterinary; D008107:Liver Diseases / Q000151:congenital / Q000473:pathology / Q000601:surgery / Q000662:veterinary*; D008297:Male; D011168:Portal System / Q000002:abnormalities* / Q000473:pathology / Q000601:surgery; D011169:Portal Vein / Q000002:abnormalities* / Q000601:surgery; D012189:Retrospective Studies