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Vet Comp Orthop Traumatol 2019; 32(01): 033-040
DOI: 10.1055/s-0038-1675797
Original Research
Georg Thieme Verlag KG Stuttgart · New York

Craniovertebral Junction Anomalies in Small Breed Dogs with Atlantoaxial Instability: A Multicentre Case–Control Study

Maja A. Waschk
1   Department of Clinical Veterinary Medicine, Clinical Radiology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
,
Beatriz Vidondo
2   Department of Clinical Research and Veterinary Public Health, Veterinary Public Health Institute, Vetsuisse Faculty, University of Bern, Liebefeld, Switzerland
,
Inés Carrera
3   Clinic for Diagnostic Imaging, Vetsuisse Faculty, University of Zürich, Zürich, Switzerland
,
Angel M. Hernandez-Guerra
4   Department of Veterinary Medicine and Surgery, Universidad Cardenal Herrera-CEU, CEU Universities, Tirant lo Blanc 7, 46115 Alfara del Patriarca, Valencia, Spain
,
Pierre Moissonnier
5   Department of Surgery, Veterinary Teaching Hospital, Veterinary School of Maisons Alfort, Maisons Alfort cedex, Paris, France
,
Ioannis N. Plessas
6   Davies Veterinary Specialists Limited, Herts, United Kingdom
,
Martin J. Schmidt
7   Clinic for Small Animals, Department of Veterinary Clinical Sciences, Justus-Liebig-University Giessen, Giessen, Germany
,
Dietmar Schnötzinger
8   Tierklinik Schwanenstadt, Schwanenstadt, Austria
,
Franck Forterre
9   Division of Small Animal Surgery, Department of Clinical Veterinary Medicine, Vetsuisse Faculty, University of Bern, Bern, Switzerland
,
Christina Precht
1   Department of Clinical Veterinary Medicine, Clinical Radiology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
› Author Affiliations
Funding None.
Further Information

Publication History

15 January 2018

01 September 2018

Publication Date:
28 November 2018 (online)

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Abstract

Objective The main purpose of this study was to define criteria to systemically describe craniovertebral junction (CVJ) anomalies and to report the prevalence of CVJ anomalies in small breed dogs with and without atlantoaxial instability (AAI).

Materials and Methods Retrospective multicentre matched case–control study evaluating magnetic resonance imaging and computed tomographic images of small breed dogs with and without AAI for the presence of CVJ anomalies.

Results One hundred and twenty-two dogs were enrolled (61 with and 61 without AAI). Only dogs with AAI had dens axis anomalies such as separation (n = 20) or a short-rounded conformation (n = 35). Patients with AAI were more likely to have atlantooccipital overlapping based on transection of McRae's line by the dorsal arch of the atlas (odds ratio [OR] = 5.62, p < 0.01), a transection of Wackenheim's clivus line (OR = 41.62, p < 0.01) and rostral indentation of the occipital bone (OR = 2.79, p < 0.05). Patients with AAI were less likely to have a larger clivus canal angle (OR = 0.94, p < 0.01) and larger occipital bone lengths (OR = 0.89, p < 0.05).

Clinical Significance Small breed dogs with AAI are more likely to have other CVJ anomalies such as atlantooccipital overlapping or dens anomalies. The grade of brachycephaly does not differ between patients with and without AAI. Certain objective criteria from human literature were found useful for the assessment of both AAI and atlantooccipital overlapping such as McRae's line, Wackenheim's clivus line, and clivus canal angle. The classification criteria used can help to evaluate CVJ anomalies in a more systematic way.

Keywords

atlantooccipital instability - atlantooccipital overlapping - dens axis anomalies - magnetic resonance imaging - computed tomography