Page 411 - Canine Lameness

21.3 ­Neurorogico giNciNi AANicgio ctNe Nolgi gim 383

region will produce a bilateral upper motor neuron (UMN)‐paresis (i.e. paraparesis) with general
proprioceptive (GP) ataxia (Chapter 4). Sensory deficits usually accompany motor deficits. If the
injury is at the level of the intumescence, multiple spinal cord segments are typically involved in
most cases, causing a polyneuropathy.
21.3.1.1 Neoplasia
Tumors affecting the nervous system of the pelvic limb, either at the intumescence or the nerves,
commonly cause pelvic limb monoparesis. For any lameness that does not quickly respond to
empirical therapy, such as anti‐inflammatory medications, neurologic conditions should be con-
sidered. Particularly in older animals, neoplasia is a common differential diagnosis (Chapter 11).

21.3.1.2 Spinal Cord Injury
Hansen Types I and II intervertebral disc herniation (IVDH), acute non‐compressive nucleus pul-
posus extrusion (ANNPE), and fibrocartilaginous embolism (FCE) are also frequent causes of
myelopathies and radiculopathies affecting the pelvic limbs. The clinical features of these diseases
are discussed in Chapter 16. Vertebral fracture and luxation (VFL) in the lumbar spine constitute
almost one‐third of all VFL (Jeffery 2010). Multisite VFL also occurs with some frequency. In con-
trast to thoracolumbar IVDH, prognosis is grave if nociception is absent secondary to VFL.
Degenerative myelopathy (DM) can result in LMN paralysis but only with longer disease dura-
tion (Coates and Wininger 2010). The classic presentation of DM is a slow and progressive clinical
course with asymmetric signs localizing to the T3–L3 spinal cord segments. Thus, it would not be
a differential for monoparesis or lameness.

21.3.1.3 Degenerative Lumbosacral Stenosis and Foraminal Stenosis
In degenerative lumbosacral stenosis (DLSS; also called lumbosacral disease, lumbosacral instability,
and cauda equina syndrome), stenosis results from chronic bony and/or soft tissue proliferation,
especially Type II IVD protrusion, reducing the size of the spinal canal and/or intervertebral fora-
men, with resulting compression, inflammation, or entrapment of the cauda equina and/or seventh
lumbar nerve as it exits, respectively (De Risio et al. 2000). This is a disease of older, large‐breed,
working dogs, especially the German Shepherd Dog, with a predilection for males. The L7–S1
intervertebral disc (IVD) is the most commonly affected site, but any site from L5 to S3 can be
affected. Stenosis of the intervertebral foramen, called foraminal stenosis, can also occur anywhere
in the lumbar spine but is most prevalent at the L7–S1 and is frequently a component of DLSS. The
resulting nerve entrapment is a common cause of pelvic limb lameness or monoparesis. Clinical
signs will be dependent on the specific nerves roots or spinal nerves affected. Dogs usually present
for vague pelvic limb problems such as trouble rising, reluctance to jump, difficulty climbing stairs,
lameness, and pain which can be ambiguous. Lameness is reported commonly and may be intermit-
tent, shifting, unilateral, or bilateral. Regional pain, either occurring spontaneously or detected dur-
ing physical examination, is common and, occasionally, may be the only historical problem. Care
should be taken to differentiate discomfort on vertebral extension from hip extension. Applying digi-
tal pressure over the lumbosacral junction (Figure 20.8 and Video 3.1) and extending the lumbosa-
cral junction by lifting the pelvis while pressing on the lumbar vertebrae (lordosis test) are two
specific methods of assessing lumbosacral pain. Extension or traction of the tail and palpation of the
lumbosacral joint on rectal examination are other methods. Careful assessment of pain responses
during hip palpation and extension is required to identify coxofemoral disease (Chapter 20). If other
neurologic deficits such as limb, tail, or anal sphincter paresis are apparent, a tentative diagnosis of
DLSS can be based on these findings. Fecal and/or urinary incontinence may be historically reported.