Page 291 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

266 CHAPTER 1

VetBooks.ir Diagnosis (T12–T18). Impingement can affect as little as one
The incidence is highest in the saddle region
Radiography of the painful area will usually show
the characteristic signs of epiphyseal lysis and sur-
reported in horses that have not been ridden, includ-
rounding sclerosis. Ventral spur formation can space or as many as 13. Impinging DSPs have been
develop between adjacent affected vertebrae. If ing young foals, although it is not known whether
the infection is close to the spinal cord, analysis these horses suffered back pain at any point in time.
of cerebrospinal fluid is likely to show evidence of Differences in thoracolumbar conformation may
inflammation and infection. Gamma scintigraphy affect the degree of impingement, and the level and
will demonstrate high radiopharmaceutical uptake type of work performed by the horse may affect
but does not necessarily differentiate this condition the likelihood of pain arising from the impinging
from trauma. areas. A slightly lordotic and/or short back confor-
mation brings the DSP tips into closer apposition.
Management Differences in the shape of the DSP, such as the more
The vague presenting symptoms often lead to the hooked conformation in the tip of Thoroughbreds,
infection being well established before a diagnosis can as well as abnormal and deformed vertebra/e, may
be made. High-dose antibiotic therapy is required, also affect the incidence in some horses. There may
preferably according to culture and sensitivity test- be a breed predisposition, with Thoroughbreds
ing, coupled with intensive supportive treatment. or part-Thoroughbreds widely reported to have a
The umbilical remnants should be scanned to check higher incidence. Back pain may develop more often
for infection in foals. If additional neurological signs in horses with impingement of DSPs and injury else-
have already developed, then treatment, however where in the axial and appendicular musculoskeletal
aggressive, is usually unsuccessful. system through the kinetic chain model of injury
and compensation, outlined earlier in the chapter.
IMPINGEMENT OF DORSAL The local pathological process occurring at the
SPINOUS PROCESSES sites of DSP impingement is well documented. As
the apices of the DSPs approach each other, the
Definition/overview dorsal one-third to one-half of each affected pro-
Also known as ‘kissing spines’ and ‘overriding dor- cess increases its rate of remodelling, demonstrated
sal spinous processes’, impingement of DSPs is one radiographically initially by sclerosis of the subperi-
of the most common conditions associated with osteal bone (Fig. 1.506), occasionally followed by
thoracolumbar pain in horses. The spaces between
the DSPs in the mid-thoracic or, less commonly,
the lumbar vertebral column narrow dorsally and
the opposing bone surfaces remodel. Any space 4 1.506
mm or less on static radiographs is considered at risk
of dynamic impingement.

Aetiology/pathophysiology
The cause of the condition in the horse still remains
unclear but it is almost certainly multifactorial in
origin. In addition, it is still unknown why only a
proportion of affected horses develop clinical back
pain. It is detected radiographically, and on gross Fig. 1.506 Impingement of dorsal spinous processes
post-mortem examination, in many clinically asymp- (kissing spines) may only be manifest as narrowing of
tomatic horses (ranging from 30 to 90% of examined the space, sometimes with sclerosis. This horse has
horses in various surveys). four kissing spines.