Front Matter

Chapter 17 Diagnosis of and Treatment Options for Disorders of the Spine 441

Common compressive spinal cord
conditions

Age‐related conditions

Age‐related degenerative conditions of the
spine are common and often are unrecognized
and underdiagnosed. Conditions include
enlargement of the articular processes, prolif­
eration of the dorsal longitudinal ligament, pro­
liferation of the yellow ligaments that connect
the neural arches, and bulging of the interverte­
bral disc. These space‐occupying changes may
encroach upon an already limited space sur­
rounding the spinal cord in predisposed breeds
(Burbidge et al., 1999). The lower cervical spine
and lumbosacral region are most commonly
affected.
Spinal cord and nerve root compressions are
often accompanied by denervation and muscle
atrophy. In the thoracic limb, the triceps muscle
group is most commonly affected. The elbows
tend to flex more than necessary during the walk
as the antagonist muscles, the triceps group, do
not resist the agonists, the elbow flexors. In the
pelvic limbs, the biceps femoris and cranial tibial
muscles are often affected. These dogs tend to
stand base‐wide and do not flex their stifles dur­
ing gaits used in propulsion. In most cases, nerve
root entrapments of the cauda equine signifi­
cantly decrease tail strength and movement.
Spinal cord or nerve root compression at both of
these sites is extremely common in older dogs
but the severity of gait alterations is variable as
certain individuals are more prone to the degen­
erative changes described (Figure 17.15).
Bulging of the annulus fibrosus into the spi­
nal canal in older dogs has been incriminated
often as a source of spinal cord compression.
However, the dynamics of this pathology have
not been studied and it is often difficult or
impossible to prove that the bulging disc alone
is the cause of any dysfunction or pain (Mayhew
et al., 2002).
A well‐documented nerve root entrapment
or foraminal stenosis has been reported in dogs
with lumbosacral stenosis. It is difficult to diag­
nose as the dogs present with intermittent
lameness. Avalanche rescue dogs may be more
prone to this condition although other breeds
have been diagnosed (Godde & Steffen, 2007)
(Figures 17.22 and 17.23). It has been noted that

larger dogs have a cranial articular process that,

with degeneration and osteophyte formation, is

likely to impinge on the L7 nerve root and/or

ganglion. Furthermore, the decreased impact

surface provided by the L7 endplate makes

larger dogs more prone to osteophyte forma­

tion. Breit and Kunzel (2001) noted that these

changes are likely to be more significant in the

athletic canine.

Intervertebral disc disease

Dogs of any breed can have intervertebral disk

degeneration with similar pathological processes

as described above (Bergknut, 2011). Conventional

radiography for the diagnosis of intervertebral

disk disease has been replaced with advanced

imaging procedures. Unfortunately, the study

of  the dynamic nature of intervertebral disc

Figure 17.23 Entrapped nerve roots removed from the

spinal cord demonstrating swelling and discoloration,

likely a result of inflammation.

Figure 17.22 Nerve root entrapment or foraminal

stenosis. A swollen nerve root can be seen at the end of

the forceps.