title: Acute non-ambulatory tetraparesis with absence of the dens in two large breed dogs: case reports with a radiographic study of relatives.
abstract: BACKGROUND
  Non-ambulatory tetraparesis with an absence of the dens of C2 (axis) has not previously been reported in large breed dogs. An absence or hypoplasia of the dens has been reported in both small, medium and large breed dogs, but not in closely related animals.
  
  
  METHODS
  Two young large-breed dogs (a German shepherd and a Standard poodle) both with an acute onset of non-ambulatory tetraparesis were subjected to physical, neurological and radiographic examinations. Both dogs were euthanased and submitted for postmortem examination within one week of onset of clinical signs. To investigate possible heritability of dens abnormalities, oblique radiographs of the cranial cervical vertebrae were taken of nine and eighteen dogs related to the German shepherd and the Standard poodle, respectively.
  
  
  RESULTS
  Absence of the dens, atlantoaxial instability and extensive spinal cord injury was found in both case dogs. Radiographs revealed a normal dens in both parents and in the seven littermates of the German shepherd. An absence or hypoplasia of the dens was diagnosed in six relatives of the Standard poodle.
  
  
  CONCLUSIONS
  Atlantoaxial subluxation with cervical spinal cord injury should be considered as a differential diagnosis in non-ambulatory tetraparetic young large breed dogs. Absence of the dens and no history of external trauma increase the likelihood for this diagnosis. This study provides evidence to suggest that absence or hypoplasia of the dens is inherited in an autosomal way in Standard poodle dogs.
authors.affiliation: Department of Companion Animal Clinical Sciences, Norwegian School of Veterinary Science, PO Box 8146, NO-0033 Oslo, Norway. oyvind.stigen@nvh.no
authors.forename: Øyvind
authors.initials: Ø
authors.lastname: Stigen
authors.forename: Mona
authors.initials: M
authors.lastname: Aleksandersen
authors.forename: Randi
authors.initials: R
authors.lastname: Sørby
authors.forename: Hannah J
authors.initials: HJ
authors.lastname: Jørgensen
mesh_terms: D000818:Animals; D001268:Atlanto-Axial Joint / Q000473:pathology; D049628:Body Size; D004283:Dog Diseases / Q000473:pathology*; D004285:Dogs; D005260:Female; D004204:Joint Dislocations / Q000473:pathology / Q000662:veterinary*; D009809:Odontoid Process / Q000033:anatomy & histology*; D010291:Paresis / Q000662:veterinary*