Neck pain is recognised in juvenile and adult horses and can have a variable aetiology, ranging from a single traumatic incident to chronic degenerative arthritis, or a combination of both.
The clinical signs can range from mild, performance-limiting stiffness to intense pain and muscular spasm. Neck pain may also be transient and can be misinterpreted by owners, making recognition difficult if the horse is not exhibiting signs of pain when examined. Additional clinical signs can include ataxia, forelimb lameness, patchy sweating and muscular atrophy.
The key to the successful management of neck-related conditions is an accurate diagnosis, but this can be challenging due to the complex anatomy, the lack of localising signs, and the inadequacy of 2D imaging techniques. Recently, the development of advanced imaging techniques such as computed tomography has allowed 3D imaging of the entire neck; this will vastly improve our ability to diagnose and treat neck pathology.
Dealing with a suspected fracture
In cases with acute onset severe pain, a cervical fracture should be considered as a potential diagnosis, particularly if a traumatic event has been witnessed, and the horse managed appropriately.
Horses with fractures of the vertebrae should be confined and provided with adequate analgesia; manipulation of the neck and gait analysis should be kept to a minimum. These horses should be kept in a calm environment and should not be tied up or excessively restrained as they may be liable to panic and exacerbate their injuries.
Survey radiography, including laterolateral, dorsoventral and oblique projections is performed, but even good-quality radiographs may fail to identify some fractures. If a fracture is suspected, but cannot be identified radiographically, then nuclear scintigraphy may be of benefit.
CT is the imaging modality of choice, but requires general anaesthesia to image the entire neck, with an inherent risk of fracture deterioration during recovery.
Both conservative and surgical management may be appropriate, depending on the fracture configuration. Conservative management is often appropriate and has the advantage of being cheaper and without the risk of recovery from general anaesthesia.
Conservative therapy can be surprisingly successful, even for severe fractures if the degree of ataxia does not lead to recumbency (see Figure 1). Owners should be warned that this can occur many weeks after the injury, particularly when the stabilising muscle spasm subsides.
As diagnostic imaging of the neck – and in particular the articular process joints – improves, so will the therapeutic options available
Recently, the use of plate fixation of cervical fractures has been described and could be considered for suitable cases, particularly now that locking compression plate technology is widely available.
Managing chronic cases
Chronic cases undergo a similar process of investigation, but with an initial detailed clinical examination, neurological examination, gait analysis and ridden assessment if appropriate. Passive and forced range of motion tests give an indication of pain or stiffness, noting any left/right asymmetry. Radiography, ultrasonography and nuclear scintigraphy are routinely employed imaging modalities and can be rewarding in many cases.
In cases where a diagnosis is not achieved, CT scanning is now an option and provides superior 3D imaging of the region (Figure 2), but further work is needed to assess the clinical significance of imaging findings.
Type I cervical vertebral malformation resulting in dynamic cord compression in the mid-cervical region is usually associated with ataxia rather than neck pain. However, Type II cervical vertebral malformation associated with arthritic enlargement of the articular process joints may lead to neck pain and lameness in addition to a degree of ataxia secondary to cord compression.
When a compressive lesion is identified, surgical stabilisation through the use an intervertebral kerf cut cylinder or ventrally-placed locking compression plates may be indicated, with a reported success rate of approximately 50-60% when assessing improvement in neurological grade alone.
The pain-relieving effects of intervertebral stabilisation in these Type II cases is poorly-described, but anecdotally, discomfort may be reduced once stabilisation is complete.
Diagnosis and treatment of arthritis
Arthritis of the articular process joints is a significant cause of neck pain, presenting with a variable degree of discomfort. These cases can be diagnostically challenging as there is considerable variation in the appearance of the joints in clinically normal individuals, making positive identification of pathological joints difficult.
Management of facet arthropathy has traditionally involved intra-articular medication with corticosteroids, and this remains the mainstay of treatment for most cases. Medication is performed under ultrasound guidance and the use of a biopsy guide can be helpful to maintain probe position relative to the needle (Figure 3).
Horses are confined for 48 hours and then field-rested for a further week before resuming light training. Medication can be repeated depending on the duration of the response. As diagnostic imaging of the neck – and in particular the articular process joints – improves, so will the therapeutic options available. Arthroscopic examination of the facet joints has been described in a cadaver study and three clinical cases (Pepe et al., 2014) and this may allow removal of osteochondral fragmentation or the debridement of cartilage lesions.
Cervical epiduroscopy has also been described (Prange et al., 2011), primarily as a diagnostic tool to locate sites of cord compression, but the technique has recently been used to deposit corticosteroid around the dorsal nerve roots of a horse with forelimb lameness which had stopped responding to medication of the articular process joints.