For the Health of It
Observation, Science, and
Equine Lameness Diagnosis
Reprinted with permission from Equine Disease Quarterly, Volume 26, Number 1
A significant number of pain-re-
lated gait abnormalities in horses
are evident only when the horse is
ridden, and are not apparent when
the horse is hand-walked or lunged.
Even when these horses are ridden,
the lameness may not be overt.
While there have been many recent
technical advancements in the
objective assessment of gait, these
are generally of limited value for
detection of bilaterally symmetrical
alterations in gait that result in re-
duced performance such as gener-
alized stiffness, lack of willingness
to work, alteration in quality of
movements such as lack of hind-
limb engagement and impulsion,
and alteration in the rider’s feel of
6 • Walking On
the contact via the reins and bit to
the horse’s mouth.
A rider often assumes that these
problems are attributable to thora-
columbar region pain, because the
problems are only manifest when
the horse is ridden. When observed
on the lunge, such horses may lean
into the circle—often more on one
rein than the other—and show ex-
aggerated contractions of the epax-
ial muscles. However, studies have
shown that experimentally induced
forelimb or hindlimb lameness may
reduce range of motion of the tho-
racolumbosacral vertebral column.
Radiographic examination may
reveal impinging spinous processes,
and this nding often results in an
erroneous conclusion implicating
thoracolumbar pain as the primary
problem. We have demonstrated
that by using diagnostic analgesia
to abolish overt or subclinical lame-
ness, the rider often appreciates an
increased range of motion of the
horse’s back.
To investigate these clinical ob-
servations, we have studied nor-
mal horses subjectively free from
lameness in hand, after flexion
test, on the lunge on both soft and
firm surfaces and when ridden. We
objectively measured body lean on
the lunge and range of movement
of the thoracolumbar region using
inertial measurement units placed
at predefined locations on the
thoracolumbar and pelvic regions.
These studies established normal
ranges of motion for the thoraco-
lumbosacral spine and demonstrat-
ed that sound horses have a small
degree of bilaterally symmetrical
body lean on the lunge. We also
measured body lean on the lunge
in lame horses and demonstrated
that there is frequently asymmetry
between left and right reins, with
greater lean compared with normal
on at least one rein. Substantial im-
provement in lameness by perform-
ing diagnostic analgesia resulted in
reduced body lean on both reins
and reestablishment of symmetry
between left and right reins. Like-
wise, when lameness was improved
by diagnostic analgesia, range of
motion of the thoracolumbosacral