Atlantoaxial subluxation and absence of transverse ligament of the atlas in a dog.
Absence of the transverse ligament of the atlas was diagnosed at necropsy in an 8-month-old Shih Tzu with radiographic signs of atlantoaxial subluxation. Symmetric ataxia, tetraparesis, and signs of pain in the vertebral canal suggested a lesion in the cervical portion of the spinal cord. Necropsy revealed absence of the transverse ligament of the atlas and malformation of dens and atlas. In addition, the alar ligaments were distinct and thick, and the atlanto-occipital and atlantoaxial joint capsules were markedly thicker than normal. Histologic examination revealed focal compressive myelopathy of the spinal cord at the level of the atlantoaxial joint.
Department of Physiological Sciences, College of Veterinary Medicine, Oklahoma State University, Stillwater 74078.
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Watson
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de Lahunta
D000818:Animals; D001268:Atlanto-Axial Joint / Q000000981:diagnostic imaging / Q000293:injuries*; D001270:Cervical Atlas / Q000002:abnormalities*; D004285:Dogs / Q000002:abnormalities* / Q000293:injuries; D004204:Joint Dislocations / Q000000981:diagnostic imaging / Q000662:veterinary*; D008022:Ligaments / Q000002:abnormalities*; D008297:Male; D011859:Radiography; D013116:Spinal Cord / Q000002:abnormalities