Abstract
Objective To evaluate the occurrence and frequency of abnormalities at the second and third
cervical vertebral junction (C2/3) in dogs with and without atlantoaxial instability
(AAI).
Study Design Retrospective multi-institutional case-controlled case series.
Animals One hundred and seventeen dogs with AAI and 117 dogs without AAI.
Methods Radiographs, together with computer tomographic images or magnetic resonanceimagesorboth,
of thecranial cervical spineof dogswerereviewed for the presence or absence of intervertebral
disc–related anomalies, osseous fusion of the vertebrae, spondylosis, or any other
anomaly of the C2/3.
Results The incidence of anomalies affecting the C2/3 in dogs with AAI was 38.46% (n = 45) and in the control group it was 11.97% (n = 14). The majority of the observed anomalies involved the intervertebral disc. In
conjunction with AAI, intervertebral disc– related anomalies were noted in 33.34%,
spondylosis in 2.56%, osseous fusion in 1.71% and a hypoplasia of the spinous process
in 0.85% of the cases. Summarized under the term intervertebral disc–related anomalies,
a morphological alteration of the intervertebral disc was noted in 10 cases with AAI,
characterized by a spherical outer shape and a minimally reduced size and a dorsal
positioning in the intervertebral space.
Conclusion There is a significantly higher incidence of anomalies affecting the C2/3 in associationwithAAI.InconjunctionwithAAI,
intervertebraldisc–related anomalies are the mostfrequentpathological finding affecting
the C2/3.
Keywords
atlantoaxial instability - craniocervical junction - C2/3 junction anomalies
