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21

Neurological Disease of the Pelvic Limb

Lisa Bartner

Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO, USA

21.1 Introduction

Dogs with monoparesis and/or neurogenic lameness are frequently presented to the veterinary
practitioner, although less commonly so than those with spinal cord conditions. It is important to
recognize and differentiate these neurologic deficits from orthopedic lameness since the causes,
treatment, and prognosis often differ greatly. Clinical signs of neurologic gait abnormalities can be
challenging to differentiate from lameness derived from orthopedic origin and therefore are the
focus of this chapter. Table 21.1 outlines common differential diagnoses and diagnostic steps for
neurological disease affecting the pelvic limb.

21.2 Relevant Anatomy

Similar to the thoracic limb, the anatomic structures of the nervous system that can be implemented
in causing a pelvic limb lameness or monoparesis include the intumescence of the spinal cord and
the efferent neuron (i.e. motor nerve) and all its constituents. The lumbosacral intumescence is
located within the central nervous system (CNS) and is composed of spinal cord segments L4–S3,
with small contributions from L3. The cell body of the efferent neurons is within the intumescence,
while the remaining aspects are located in the peripheral nervous system (PNS).
There are seven pairs of lumbar nerves exiting the spinal cord bilaterally, through a similarly
numbered intervertebral foramen and caudal to the same numbered vertebra. As the spinal cord
courses caudally, each segment is shorter than the vertebral segment and as a result the spinal cord
ends around the fifth or sixth vertebral bodies (Figure 4.2). In large dog breeds, this may be more
cranially positioned (fifth lumbar vertebra) and in small dogs, this can be located more caudally
(e.g. sixth lumbar vertebra). Thus, the entirety of the lumbosacral intumescence lies within the
spinal canal between the third and fifth lumbar vertebral bodies (Figure 4.2). For this reason, the
last several pairs of spinal nerves extend longer distances within the vertebral canal before exiting
their respective intervertebral foramen.
The dorsal nerve root branches exit the foramina and innervate epaxial muscles while the last
four or five ventral branches of the lumbar nerves and the ventral rootlets of all sacral nerves join

Canine Lameness, First Edition. Edited by Felix Michael Duerr.
© 2020 John Wiley & Sons, Inc. Published 2020 by John Wiley & Sons, Inc.
Companion website: www.wiley.com/go/duerr/lameness