Page 296 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

Musculoskeletal system: 1.7b The axial skeleton – thoracolumbar region 271

VetBooks.ir 1.515

Fig. 1.515 Longitudinal ultrasound
image of a discrete focal area of soft-
tissue swelling between T16 and T17.
A hypoechoic area of supraspinous ligament
is visible, consistent with injury.

Management of OA in these joints is unknown but it has been
In acute injuries with avulsion fractures, symptom- recorded throughout the thoracolumbar vertebral
atic treatment with rest and gentle field turnout is column. As with other conditions of this region,
indicated. Long periods of rest are rarely needed clinical signs do not correlate with the degree of
and physiotherapy to reverse reflex muscle spasm pathology observed on diagnostic imaging or post-
is indicated as soon as the acute inflammation is mortem examination. The lesions are most common
controlled. Topical anti-inflammatory drugs, such around the thoracolumbar junction and may occur
as diclofenac, may be beneficial given the subcu- concurrently with impingement of the DSPs. It has
taneous position of the supraspinous ligament. been suggested that the presence of impinging DSPs
Bisphosphonate drugs are contraindicated in the can lead to changes in back movement and adversely
case of acute avulsion fractures, but with chronicity affect the function of the facet joints, leading to OA.
they may be of considerable benefit, reversing some In a post-mortem survey of young Thoroughbred
of the increased osteoclast action in the enthesis and racehorses, the majority had evidence of stress
reducing pain. Focused extracorporeal or radial- fractures of the vertebral lamina adjacent to the
pulsed shock-wave therapy is potentially beneficial dorsal intervertebral joints, and there was a posi-
to reduce pain and encourage normal function. tive correlation with the presence of OA, suggest-
Interspinous desmotomy can resolve pain in horses ing that laminar stress fractures are common and
with chronic reactive inter- and supraspinous enthe- could lead to dorsal intervertebral joint OA in this
seopathy in the absence of DSP impingement. group of animals. Stress fractures are, however,
extremely uncommon in other types of horse, such
OSTEOARTHRITIS as Sport horses, where OA of the facet joints is more
common in middle-aged to older horses, suggest-
Definition/overview ing chronic wear and tear as a major factor in their
OA of the thoracolumbar vertebral column occurs at aetiology.
the thoracic and lumbar dorsal intervertebral joints.
Clinical presentation
Aetiology/pathophysiology The onset of clinical signs is insidious and can range
The dorsal intervertebral joints are formed by from overt vertebral column pain to poor perfor-
the cranial and caudal facets of the articular pro- mance. There are no clinical signs that can be used
cesses in the thoracolumbar vertebral column (see to differentiate this condition from other back
Figs. 1.475, 1.476, 1.484, 1.487). The incidence problems.