We describe a three‐year‐old English Springer Spaniel presented with peracute and traumatic onset of cervical spinal cord signs of non‐ambulatory tetraparesis and bilateral Horner's syndrome. MRI and CT revealed aplasia of the odontoid process, dramatic dorsal displacement of the axis and marked compression of the spinal cord with changes consistent with oedema and inflammation. Surgical reduction of the vertebrae and atlantoaxial arthrodesis was successful, with recovery of ambulation over six weeks. A follow‐up CT six weeks later confirmed stability of the implants. The dog is clinically stable 19 months on. Traumatic atlantoaxial subluxation associated with congenital dysplasia of the odontoid process is rarely reported in medium breed dogs.

Case series summary We describe here the surgical management of two pure breed cats with traumatic atlantoaxial subluxation. One cat was ambulatory tetraparetic on presentation and the second was tetraplegic, both with cervical spinal pain and acute onset of paresis with subsequent deterioration. MRI was performed in both cases, demonstrating spinal cord injury. Flexed lateral cervical radiographs were needed to confirm atlantoaxial subluxation in one case. CT was performed for surgical planning and surgical stabilisation was achieved with threaded pins and polymethyl methacrylate (PMMA) cement; odontoidectomy was required in one case. Both cats showed improvement postoperatively, with no complications or deterioration seen. Following surgery, one cat made a complete recovery; however, the second cat retained significant deficits. Relevance and novel information We present the first report of surgically managed atlantoaxial subluxation of traumatic aetiology in cats, and report its occurrence in two novel breeds for this disease, Ragdoll and Persian. One case required odontoidectomy due to previous fracture and malunion of the odontoid process of the axis; both cases underwent surgical stabilisation of the atlantoaxial joint utilising multiple threaded pins and PMMA cement without transarticular implants – a technique that has not been previously reported in cats.