Application of a Modified Dorsal Wiring Method in Toy Breed Dogs With Atlantoaxial Subluxation.

Abstract

Atlantoaxial subluxation (AAS) is a congenital or traumatic condition that often requires surgical stabilization. Surgery is performed via a ventral or dorsal approach. A ventral approach is challenging in toy breed dogs due to their small-sized bones. Reducing AAS by orthopedic wire via a dorsal approach can cause iatrogenic spinal cord damage. Due to these limitations, a Kishigami atlantoaxial tension band (Kishigami AATB) that remains in the epidural space has been devised. Similar to the Kishigami AATB, the present study developed a modified dorsal wiring method and evaluated it in toy breed dogs with AAS. Medical data of toy breed dogs with AAS that underwent surgical stabilization using the modified dorsal wiring method from 2017 to 2020 were retrospectively reviewed. A total of 10 dogs were analyzed. Regarding the history of these dogs, six dogs had congenital AAS, and the remaining four dogs had traumatic AAS. Evaluation via computed tomography was available for five dogs, of which two dogs were identified as having incomplete ossification of their atlas. Although four dogs required a revision surgery because of recurrence of clinical signs or fracture of the atlas, final functional improvement was achieved in nine dogs. One dog showed worsened neurological status that led to death. Clinical results with the modified dorsal wiring method were similar to those with the Kishigami AATB. The modified dorsal wiring method is versatile as it could be applied to various shapes of dogs' atlas. Considering the shape of the atlas, it is recommended to apply the implant as far from the midline of the dorsal arch as possible to avoid fractures. With selection of suitable patients, this modified dorsal wiring method can be applied to dorsal stabilization of AAS in toy breed dogs.