Introduction
Cranial mid-body fractures of the axis in horses result from
hyperflexion of the neck and are associated with lateral bending falls
or impact into fixed objects (Nixon 2020). These fractures propagate
transversely through the body of the axis, at the level of the cranial
physis, and enter the vertebral canal near the cranial vertebral
foramen. Dorsal displacement of the body of the axis in relation to the
cranial fracture fragment and mild lateromedial displacement are common
(Nixon 2020). The literature on management of equine cranial mid-body
axis fractures is scarce. One case series reports successful
conservative treatment in four of five horses diagnosed with odontoid
process fractures (Vos et al. 2008). The four horses that
returned to athletic activity presented with a cranial mid-body fracture
of the axis, referred to in the case series as a Type II odontoid
fracture (Anderson and D’Alonzo 1974), whereas the fifth horse,
euthanized several hours after admission, due to severe and
deteriorating neurological symptoms, was diagnosed with an avulsion
fracture of the odontoid process, also referred to as
a Type I odontoid fracture (Anderson and D’Alonzo 1974,Vos et al.2008). All horses but one showed swelling at the level of the axis,
signs of neck pain and neurological compromise upon presentation (Voset al. 2008). In the authors experience, conservative treatment
of mild to moderately displaced cranial mid-body axis fractures has been
unsuccessful. Out of three cases, one case was clinically sound but was
retired eight months after initial presentation because of persisting
severe neck stiffness, one case was euthanized three and a half months
after injury because of acute neurological deterioration, and another
became tetraplegic four days after fracture diagnosis and was
euthanized. Following this personal experience, the authors recommended
surgical treatment for an 8-year-old warmblood gelding admitted to the
hospital with a cranial mid-body axis fracture. The authors report
successful reduction and stabilization of the fracture using a 4.5mm
locking compression T-plate.