Plus-Hex CLINICAL
Introduction
Patients with spinal cord disease can present with a wide range of neurological dysfunction. Milder cases may demonstrate ataxia, characterised by loss of balance, uncoordinated movements and paw scuffing during ambulation. More severe cases may present with tetraplegia, resulting in paralysis of all four limbs.
There are varying levels of neurological dysfunction commonly observed in spinal patients, and the severity of clinical signs reflects both the degree of spinal cord damage and the specific location of the disease or injury( Table 1).
These divisions are essential for neurolocalisation, as each region contains specific spinal cord segments responsible for distinct motor and sensory functions.
Between each vertebra lies an intervertebral disc, which provides cushioning and flexibility to the spine( Figure 1). Each disc acts as a shock absorber and consists of two structurally distinct components: a tough, fibrous outer ring known as the annulus fibrosus, formed from concentric layers of dense connective tissue, and a gelatinous central core called the nucleus pulposus, which distributes compressive forces evenly across the disc [ 3 ].
Table 1. Common neurological terms.
Term
Definition
Ataxia
Paraparesis / paraparetic
Paraplegia / paraplegic
Tetraparesis Tetraplegia Hemiparesis Hemiplegia Monoparesis Monoplegia
Loss of balance and coordination
Weakness in the hindlimbs
Paralysis of the hindlimbs
Weakness in all four limbs Paralysis of all four limbs Weakness down one side Paralysis of one side Weakness of one limb Paralysis of one limb
Assessment is undertaken by the veterinary surgeon( VS) through clinical examination to establish potential differential diagnoses, guided by the fivefinger rule( onset, progression, pain, lateralisation and neurological localisation) [ 1 ].
Consideration should also be given to the patient ' s signalment, including age and breed, as chondrodystrophic breeds( characterised by elongated backs and shortened limbs), such as the dachshund, are predisposed to certain neurological disorders compared with breeds of normal conformation [ 2 ].
Figure 1. The intervertebral disc( shown in blue) is positioned between the vertebrae and acts as a cushion.
Intervertebral disc herniation occurs when the nucleus pulposus breaches the annulus fibrosus and displaces dorsally into the vertebral canal, resulting in compression of the spinal cord( Figure 2). This displacement, commonly referred to as a‘ slipped disc’, disrupts normal neural transmission, with the resulting clinical signs varying according to the spinal region affected. The mechanism can be visualised by imagining pressure applied to a jam-filled doughnut: as the outer layer is compressed, the central filling is forced outwards through the weakened area [ 4 ]. This analogy illustrates the pathophysiology of disc rupture and the subsequent intrusion of disc material into the vertebral canal.
The vertebral column is composed of a series of vertebrae arranged into four neurologically significant regions:
• C1 – C5( cervical)
• C6 – T2( cervicothoracic)
• T3 – L3( thoracolumbar)
• L4 – S3( lumbosacral) [ 2 ].
Figure 2. A herniated disc protruding on to the spinal cord.
Volume 41( 3) • June 2026
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