Imaging features of atlanto-occipital overlapping in dogs

Vet Radiol Ultrasound. 2009 May-Jun;50(3):264-8. doi: 10.1111/j.1740-8261.2009.01531.x.

Abstract

The imaging features of four dogs with atlanto-occipital overlapping are described. This malformation appeared to play a role in the development of neck pain, ataxia, variable cerebellar involvement, medullary kinking, and possibly syringomyelia. Using cervical radiographs, three of the four dogs were initially diagnosed with an atlanto-axial malformation. Because this disorder could not account for all clinical signs, magnetic resonance and computed tomography images were also acquired. These provided a more complete evaluation of the craniocervical junction, allowing detection of atlanto-occipital overlapping, medullary kinking, occipital dysplasia, abnormalities of the dens, and syringomyelia in these dogs. Head position during imaging affected the degree of atlanto-occipital overlap. These findings emphasize the need to modify the currently accepted imaging recommendations for dogs with head and neck pain and/or cranial cervical myelopathy. We suggest that the entire craniocervical junction be evaluated, even if atlanto-axial subluxation has already been detected. Moreover, we propose that atlanto-occipital overlapping is a perhaps underrecognized disorder that can influence the clinical signs and therapeutic outcome of dogs with anomalies of the craniocervical junction.

Publication types

  • Case Reports

MeSH terms

  • Animals
  • Cervical Atlas / abnormalities
  • Cervical Atlas / diagnostic imaging*
  • Dog Diseases / diagnostic imaging*
  • Dogs / abnormalities*
  • Female
  • Joint Dislocations / diagnostic imaging
  • Joint Dislocations / veterinary
  • Male
  • Occipital Bone / abnormalities
  • Occipital Bone / diagnostic imaging*
  • Radiography