Peer-reviewed veterinary case report
Joint shape differences in small breed dogs with atlantoaxial
By Pack, Felix et al.·Published in Frontiers in veterinary science·2025·Department of Clinical Veterinary Science·View original on PubMed →
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Original publication title: Morphometric study of the atlantooccipital and the lateral atlantoaxial joints in small breed dogs with and without atlantoaxial instability.
- Species:
- dog
Plain-English summary
A group of small breed dogs with atlantoaxial instability (AAI) was studied to see if their neck joints were different compared to dogs without this condition. Researchers found that the joint surfaces in dogs with AAI were shallower, which could suggest a structural issue that might contribute to their instability. The study involved CT scans of 33 dogs, revealing that the atlantooccipital joint surfaces were notably flatter in those with AAI. Understanding these differences could help veterinarians better diagnose and treat small breed dogs suffering from neck problems.
Abstract
INTRODUCTION: The combination of atlantoaxial instability (AAI) with several abnormalities and malformations of the craniovertebral junction in small breed dogs has been described, however there is limited knowledge regarding morphometric alterations of the synovial joints in this region. This study aimed to evaluate the morphometric differences of the lateral atlantoaxial and the atlantooccipital joints between dogs with and without AAI using computed tomography (CT) scans. MATERIALS AND METHODS: This retrospective observational case-control study analyzed multiplanar reconstructed CT scans of 33 small and toy breed dogs (11 with AAI and 22 controls without AAI). The depth-to-length ratios of the articular surfaces of the atlantooccipital and lateral atlantoaxial joints were measured in dorsal and sagittal reconstructions and tested for significant differences between AAI and control groups. RESULTS: The depth-to-length ratio of the occipital condyles in sagittal ( < 0.001) and dorsal planes ( < 0.007), as well as the facies articularis cranialis of the atlas in sagittal plane ( < 0.001), were significantly smaller in the AAI group, indicating that the occipital condyle and the cranial articular surface of the atlas were more shallow in the AAI group compared to the control group. The depth-to-length ratios of the lateral atlantoaxial joint surfaces were generally lower than those of the atlantooccipital joint, consistent with a flatter joint conformation, and some differences between AAI and control dogs were detected; however, these patterns were not consistent across planes. DISCUSSION AND CONCLUSION: The atlantooccipital joint surfaces were more shallow in small breed dogs with AAI compared to controls. These results suggest that a certain degree of atlantooccipital joint dysplasia may be more commonly present in dogs with AAI, whereas morphometric alterations of the lateral atlantoaxial joints appear more complex and less consistently differentiated between groups.
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Search related cases →Original publication on PubMed: https://pubmed.ncbi.nlm.nih.gov/41737917/