Page 149 - Adams and Stashak's Lameness in Horses, 7th Edition

Examination for Lameness 115

NECK minimize variability. 7,8,18 For instance, the same person
should flex the right and left limbs at any location for the
The neck should be examined for contour from the
VetBooks.ir side and axial alignment from the front and rear. Different people may have slight differences in the way
same period of time so they can be accurately compared.
Excessive ventral arching of the neck in the mid‐cervi­
they hold the limb or apply pressure to the limb, which
cal region may be seen in some cases of cervical verte­
bral malformation. A straight (extended) poll can be can alter the responses. Despite this potential for varia­
bility, the flexion techniques performed by experienced
seen with atlanto‐occipital and atlanto‐axial malforma­ veterinarians are usually sufficient to objectively assess
tions. Splinting and spastic contraction of the neck responses to flexion. Two relatively recent studies using
7
muscles with or without signs of spinal ataxia is often inertial sensor‐based systems have documented that a
consistent with vertebral fracture. Generally these positive response to flexion results in significant changes
horses are very painful. to the objective measurements of pelvic movement. 9,14
The transverse processes should be palpated for However, the variation in measured symmetry following
alignment and symmetry and to detect evidence of atro­ flexion within and between horses showed that the indi­
phy. Muscle atrophy is most often observed in the cau­ vidual response to flexion may be highly variable. 14
dal neck region dorsal to the cervical vertebrae and may Passive flexion usually refers to manipulation of a
be symmetric or asymmetric. Swelling of the neck either joint during routine palpation of the horse, and pain
lateral or ventral is generally a sign of trauma or detected with passive flexion often predicts a significant
infection. response to a subsequent flexion test. However, flexion
The neck should be flexed laterally and ventrally and tests can also be used to subjectively assess the severity
extended to assess flexibility, range of motion, and pain. of damage within an affected joint(s). In general, the
Lateral flexing can be done by pulling the horse’s head severity of damage is often proportional to the severity
by the halter to one side and then to the other. of the response to the flexion test. For instance, horses
Alternatively, lateral neck flexion can be encouraged by with severe responses to carpal, fetlock, or stifle flexion
holding a “treat” at the horse’s shoulder. Most horses typically have significant intra‐articular or extra‐articu­
should be able to flex their neck laterally enough that lar pathology. However, flexion tests are not specific for
the muzzle almost contacts the craniolateral shoulder the joint because it is nearly impossible to flex a single
region. Ventroflexion is assessed by feeding the horse joint without affecting other nearby joints and soft tis­
from the ground level, and extension is evaluated by sues. Flexion of a joint not only increases the intra‐artic­
elevating the head and neck. Resistance to neck move­ ular and subchondral bone intraosseous pressures
ment in any direction is usually due to pain and can be within the joint but also compresses and stretches the
from many potential causes. joint capsule and surrounding soft tissues. 12,16 The
numerous other “structures” that are being manipulated
FLEXION TESTS/MANIPULATION with any flexion test should always be considered when
interpreting the clinical significance of flexion tests.
Most flexion tests, regardless of the location, are usu­ The responses to flexion should be graded in some
ally performed for 30–60 seconds and are a subjective manner and included in the records. This is most impor­
method to further isolate the site of the lameness (Videos tant when reevaluating the lameness to more accurately
2.5 and 2.6). In one recent study, flexion duration for 5 determine whether improvement is being made. The
seconds had similar responses to tests performed for 60‐ author uses a grading scale of negative, mild response,
second questioning whether the duration of flexion is moderate response, and severe response to assess the
that important. In addition, the response to flexion flexion tests. Alternatively, a plus‐minus system may be
1
tests must be interpreted in light of clinical findings used with “–” being no response and 1+ equating to
because many otherwise normal horses may demonstrate mild, 2+ to moderate, and 3+ to severe. Regardless of
positive responses. 11,18 These false‐positive responses are the system used, the responses to flexion are a very
thought to be directly related to the force applied to the important aspect of the lameness examination and
limb. In one study only 20 of 50 horses responded to a should be recorded (Video 2.5). Additionally, changes in
“normal” distal limb flexion, while 49 of 50 horses lameness in the limb not being flexed (weight‐bearing
11
responded to a “firm” distal limb flexion. Another limb) should also be recorded because this is often an
study revealed that more than 60% of 100 sound horses important clinical finding. This contralateral response to
had a positive response to distal limb flexion and that flexion tends to occur most commonly in horses with
the positive outcome increased significantly with age. bilateral hock and carpal problems. 12
3
Both of these studies question the validity of distal limb
flexion tests to predict future joint‐related problems. 3,11 DISTAL LIMB/PHALANGEAL/FETLOCK FLEXION
In addition, false‐positive responses to flexion seem to
occur more commonly in horses in active work than in Attempts can be made to isolate the fetlock joint
horses that have been rested or turned out to pasture. from the pastern and coffin joints during flexion of the
12
In general, there are more false‐positive results to flex­ distal limb (Video 2.5). However, it is nearly impossible
ion at any location than false‐negative results, but both to only flex the fetlock or only flex the pastern or coffin
can occur. False‐positive responses are most common in joints. Flexion of the fetlock joint can be performed by
front fetlock flexion tests. placing one hand on the dorsal MC/MT and pulling up
Because both the amount of force and the duration for on the pastern with the opposite hand (Figure 2.59).
which it is applied may affect the response to flexion, the Flexion of just the phalangeal joints is performed by
procedure should be standardized as much as possible to maintaining fetlock extension by placing one hand on