Page 304 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

Musculoskeletal system: 1.7c The axial skeleton – pelvis 279

VetBooks.ir suspected or confirmed SI pain, the scant infor- painful and asymptomatic horses, making identi-
fication of clinically significant findings difficult.
mation available suggests that the prognosis for
return to previous athletic activity is fair, particu-
larly when an adequate rehabilitation protocol is Radiography of the lumbosacral joint in adult
horses is problematic and limited to visualisation
instituted and underlying/concomitant lameness of the DSPs. Transrectal ultrasonography can be
is treated. used to image the lumbosacral joint from the ven-
tral aspect (Figs. 1.526, 1.527). Lumbosacral joint
LUMBOSACRAL REGION PROBLEMS

Definition/overview 1.526
Pathology in the lumbosacral region is a source of
back pain and poor performance in horses of all
disciplines, and is difficult to differentiate from
other sources of pain in the thoracolumbar and SI Dorsal
ligament
regions. In the horse, the lumbosacral joint is the
most mobile intervertebral joint of the back, which
makes it more susceptible to injury than other inter- Cord
vertebral joints. The lumbosacral joint is composed
of five separate joints: the intervertebral disc space
between the last lumbar and the first sacral verte- Ventral
brae; the medial and lateral synovial joints between ligament
the articular processes; and the medial and lateral
intertransverse joints between the transverse pro-
cesses of the last lumbar vertebra and the sacrum. Disc
Variation in anatomy of the lumbosacral region has L6
been described including changes in the traditional S1
vertebral formula (number of lumbar and sacral
vertebrae), boney fusion of the lumbar vertebra to
the sacrum (sacralisation), changes in angulation of Fig. 1.526 Endorectal ultrasound image of a normal
the vertebral joints and the presence of transitional lumbosacral joint space showing the lumbosacral disc
vertebrae. (Photo courtesy Diane Isbell)

Clinical presentation 1.527
Clinically, it is not possible to differentiate lum-
bosacral pain from other sources of pain in the
caudal lumbar, lumbosacral or SI region, and local
analgesia of the lumbosacral joint is not possible.
Local analgesia of the SI joint can potentially
decrease pain in this region and cause false-positive
responses.

Diagnosis
Diagnosing the exact problem can be challenging
as radiography, ultrasonography and scintigraphy
have limitations due to superimposition of osse-
ous and soft-tissue structures and the large size of
the animal. Mild scintigraphic, radiographic and Fig. 1.527 Endorectal examination of a lumbosacral
ultrasonographic changes may be present in both disc with calcification. (Photo courtesy Diane Isbell)