Page 823 - Adams and Stashak's Lameness in Horses, 7th Edition

Lameness Associated with the Axial Skeleton 789

travers, and half pass—can show alterations when lum- bigger breeds often give disappointing images, and it is
bar facet joints are involved because the rotation in the difficult to differentiate their facet joints from the massive
VetBooks.ir these movements. In racing, dorsoventral flexion of the views can sometimes facilitate imaging of the unilateral
vertebral bodies of the lumbar spine. Oblique lateral
lumbosacral region makes an important contribution to
facet joints of the lumbar spine. Even under general
lumbar spine is a prominent contribution to the propul-
sion phase of the hindlimbs, so loss of performance may anesthesia, the facet joints of the sacrum and the adja-
be caused by lumbar facet joint syndrome. cent pelvic bones cannot be viewed accurately with
radiography. However, the coccygeal vertebrae are easy
to see with radiography.
Diagnosis
Ultrasonography is a very useful tool for examining
The thoracic vertebrae can be viewed with radiogra- the facet joints of the vertebral column. It can give
9
phy with the lungs facilitating radiographic imaging in information about ligamentous structures and muscle
the cranial part of the thorax. In most horses, the verte- conditions (Figure 6.34), high muscle tension can be
bral bodies of T1 through T15–T16 can be imaged ade- shown as increased muscle echogenicity, and fascicula-
quately to evaluate the intervertebral disc spaces and tions can be visualized in real‐time ultrasonography. The
vertebral body as well as the ventral aspect of the verte- supraspinous ligament, interspinous ligaments, and dor-
brae. In the more cranial part of the thorax, it is diffi- sal sacral ligaments can be examined with this as well.
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cult to get a clear image of the intervertebral disc space Paramedian longitudinal views of the facet joints can be
and the facet joints because of the superimposing struc- used to determine the edges of these joints, which should
tures of the scapulae. Depending on the conformation of normally be smooth and bilaterally symmetrical.
the horse, the width of its thorax, musculature, and Possible effusion of these joints, bony proliferations at
body condition, oblique lateral views can isolate the uni- the joint margins, and fractures and avulsion fragments
lateral facet joints from T5–T7 to T18 (Figure 6.33). and ankylosis of the facet joints (Figures 6.34–6.36) can
When pathology of the facet joints is present, there are be seen with ultrasound.
signs of sclerosis of the bone just around the facet joint, Doppler ultrasonography can provide valuable infor-
narrowing of the joint space, irregular shape of the joint mation about vascular activity around the facet joints
space, and spur formation at the edges of the joint space (Figure 6.37). In cases of synovitis or osteoarthritis of a
or complete ankylosis visible on the radiographs. facet joint, increased vascular activity can be visualized
Lumbar vertebrae are the most difficult to visualize around the facet joint, especially when the adjacent facet
with radiography. Especially well‐muscled horses of the joints and the contralateral facet joint are compared.

Figure 6.33. Radiographic image of the thoracic spine, (oblique and some sclerosis in the right facet joints. This is indicative of
lateral view) to expose the left facet joints (circles) at the left, and osteoarthritis of the right thoracic facet joints.
the right facet joints at the right. Note the more irregular joint space