Page 813 - Adams and Stashak's Lameness in Horses, 7th Edition

Lameness Associated with the Axial Skeleton 779

sacroiliac region during the phase when the leading With acute sacroiliac disease there is clear pain in the
hindlimb (left hindlimb in left lead canter) carries the hindquarters or back. The horse can exhibit severe mus-
VetBooks.ir roiliac lesions are present, the horse often alters its gait favoring one hindlimb. Even non‐weight‐bearing lame-
cle spasm, clear asymmetry of the tuber sacrales, and
entire body load after the suspension phase. When sac-
ness is sometimes found in cases of acute sacroiliac dis-
to relieve this unilateral loading by cantering more as a
bunny hop in which there is less separation of footfalls ease, as with subluxation.
of the hindlimbs. Horses with sacroiliac pathology also The lameness is less pronounced in more chronic
change leads or cross canter frequently. Due to this aug- cases. Muscle atrophy of the affected side may be noticed
mentation of signs in the canter, disciplines that are with unilateral sacroiliac disease. Shorter stride length,
judged on the quality of the canter, for example, dres- mostly in the cranial phase, of the affected limb is a very
sage and Western pleasure, or those that require a good‐ common finding, as is lack of propulsion, less hindlimb
quality canter for optimum performance, as in hunting, engagement, and lack of collection (coming under).
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jumping, and racing, comprise a greater proportion of The horse may appear stiff and rigid with lack of latero-
clients who bring their horses with sacroiliac pathology flexion in the lumbosacral region. Asymmetric position-
to the author’s practice. ing of the tail is often observed, with a deviation of the
Racing horses with poor performance often have tail in the direction of the affected ligament; this releases
mild signs of sacroiliac disease, especially the young, tension to the short part of the dorsal sacral ligament
immature Thoroughbred in which mild to moderate when the ligament is involved (Figure 6.20). 24
strain to the dorsal sacral ligaments is diagnosed In stance as well as in motion, the affected side often
frequently. Sacroiliac disease is very common in has a slight hip drop. This is different than with hindlimb
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Standardbred racehorses, again with desmopathy of the lameness, in which the hip drop often is just evident in
dorsal sacral ligaments as the most prominent diagnosis; motion and less so in stance. Flexion tests of the
however, in the author’s experience, osteoarthritis of the hindlimbs may be positive; note that secondary over-
sacroiliac joint(s) is diagnosed in this breed more often load of hindlimb structures may become more obvious
than in any other breed. Incomplete or complete rupture in sacroiliac disease. In most cases with primary sacro-
of the dorsal sacral ligaments and incongruence of the iliac disease, the flexion tests are questionable or nega-
position of the tuber sacrales (as a sign for clinical sub- tive. However, standing on the affected limb when the
luxation of the sacroiliac joint) are seen, mostly in contralateral limb is lifted and flexed can pronounce
racehorses. lameness of the affected side after the flexion test, result-
Behavioral issues such as kicking, rearing, striking, ing in more pronounced lameness on the contralateral
and bucking, as well as resisting going forward, are side. During the flexion tests the horse may show reluc-
quite often associated with sacroiliac pathology. Riders tance to stand on the affected limb or lean over to the
frequently report that these behaviors occur when the affected side, so the stance limb is in midposition, which
horse is asked to canter, and it can be difficult to deter- reduces rotational forces to the pelvic structures.
mine whether these are training/behavior issues or a Examination of the mobility of the spine can give spe-
reaction to pain. 2,3 cific information about reduced range of motion in the
Some horses do not show evidence of sacroiliac dis- sacroiliac and lumbosacral region. Reflexes that induce
ease until ridden under saddle. However, severe sacroil- dorsal and ventral flexion can be suppressed due to pain
iac injury such as acute subluxation or even dislocation in the sacroiliac region. Passive lateral flexion is quite
of one of the sacroiliac joints or rupture of the sacral often reduced to the side of the location of the sacroiliac
ligaments can cause severe hindlimb lameness, even pain.
non‐weight‐bearing lameness. Provocation tests are useful to determine the location
of the pain within the sacroiliac region. Manipulation
of the tuber ischium forward with one hand and moving
DIAGNOSIS the tuber coxae of the same side upward and down-
ward introduces ventroflexion and rotation in the
Clinical examination of horses with suspected sacro- sacroiliac joints. Pressure on the tuber sacrale identifies
iliac disease is the same as any other lameness examina- pain at the insertion of the dorsal sacral ligament.
tion. Emphasis is placed on observation of the gaits, in Recently, a retrospective study has provided some
the walk, especially with serpentines, and at the canter clinical guidance to help determine if sacroiliac dysfunc-
in softer footing as well as eventually under saddle. tion is likely to be present based on the observation of
Lateral walk (movement of the ipsilateral pair of legs at six clinical parameters during the standard lameness
the same moment, like a camelid) in serpentines is a reli- examination. These parameters are tracking narrow
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able sign of reduced mobility of the spine. When sacro- behind, lateral walk on a serpentine, haunches in or out
iliac pain is present, especially when the dorsal sacral in a straight line and on circles, an asymmetric tail posi-
ligaments are involved, mobility of the tail can be tion, a bunny hop canter, and a reduced mobility of the
reduced. Very often the tail is fixed in one position and lumbosacral region. Ultrasound examination provides
does not move when the horse walks in a serpentine. more detailed information about the condition of the
Loss of the quality of the canter in one lead is a very dorsal sacral ligaments. 4,17,19 Dorsal percutaneous ultra-
strong sign for sacroiliac pain. This can be presented as sonography using a linear probe with a higher frequency
less propulsion, less engagement, cross canter, no‐sound (10–15 MHz) is very useful for evaluating the dorsal
3‐beat canter, or even a bunny hop canter. Asymmetry of sacral ligaments and their attachment to the tuber
the tuber sacrales can be observed; however, this is also sacrale. Transverse views are used to identify the liga-
found in clinically normal horses. 2,3,9,12,15 ments, check their size, and compare the left and right