Page 1027 - Adams and Stashak's Lameness in Horses, 7th Edition

Occupational‐Related Lameness Conditions 993

The choice of corticosteroid is often imposed by the retically block the proximal suspensory and not the
show schedule and regulations: e.g. methylprednisolone lower hock joints. It also offers the advantage of not
VetBooks.ir show, 15 days prior to an USEF‐regulated show. Such blocks could be performed on horses in hand or ridden
interfering with potential ultrasound evaluation. Such
has to be used at least 60 days prior to an FEI‐regulated
treatment is often repeated at regular intervals to avoid
if the lameness is most obvious then or only felt.
losing performance and weeks of showing and help pre­ Ultrasonography is the most used way to diagnose
vent the development of secondary issues. PSD, evaluating possible enlargement, loss of fiber pat­
Horses are often treated also with systemic injections tern, and core lesions. Ultrasound evaluation can be
of “maintenance” therapy such as glycosaminoglycans challenging especially when evaluating hindlimb sus­
or hyaluronic acid. pensory ligaments, as the lesions are often subtle, and
In some cases refractory to steroids, biologics such as there is significant variation in the muscle fibers of the
IRAP have been used with some unexpected success. In suspensory ligament that could appear as lesions to even
advanced cases, fusion of the lower hock joints could be experienced ultrasonographers. The transducer should
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performed either chemically (using ethyl alcohol or be applied from medial plantar, and the ligament should
monoiodoacetate 4,8,33 ) or surgically. Horses will usually be evaluated on cross‐sectional and longitudinal planes.
be able to perform at lower classes in such case. Comparisons with the opposite limb should be per­
When hock injections seem to improve the lameness formed if there are any doubts about potential muscle
but only for short periods, some thoughts should be fibers.
given to the possibility of other injuries in the close Radiographs could show bony remodeling at the
proximity of the TMT and DIT joints such as proximal level of the proximal palmar or plantar cortex and in
suspensory ligament desmitis. more severe cases avulsion fractures. Nuclear scintigra­
phy can also be useful detecting increased radiopharma­
ceutical uptake at the level of the insertion of the
Suspensory Desmitis proximal suspensory ligament, indicating a bony com­
ponent to the lameness.
PSD is the single most common soft tissue lesion of In questionable cases, the use of cross‐sectional imag­
especially dressage horses and hunter/jumpers. In the ing MRI and CECT is extremely useful, not only to con­
hindlimbs, PSD is likely due to the increased load placed firm lesions but also to rule out other causes of lameness
by collection work in dressage and by jumping in hunter/ responding to local analgesia of the site.
jumpers and eventers. In the forelimbs, it is often seen Treatment of PSD includes rest and controlled exer­
with overzealous movers and related to the marked cise and therapeutic shoeing (shoe with wide toe and
metacarpophalangeal hyperextension upon landing thin branches to load the DDFT more), which is often
from jumps. Suspensory branch lesions are most com­ sufficient treating for forelimb PSD but rarely resolves
mon on the forelimbs in eventers and high‐level show hindlimb desmitis. The addition of ESWT, laser therapy,
jumpers. 14 and intralesional injections (of biological therapies) is
PSD appears most often insidiously in the hind limbs, helpful when dealing with hindlimb desmitis and has
and lameness or loss of performance seems to subside somewhat improved the prognosis. Ligament splitting is
temporarily to small periods of rest. The condition is performed not only when a fresh core lesion is present
often bilateral, and this delays recognition of the prob­ but also in chronic cases. 19
lem further. In the forelimbs, there is often a more acute Fasciotomy and neurectomy of the deep branch of
lameness initially. Lameness is often more obvious on the lateral plantar nerve and neurectomy alone have
2
the circle with the leg on the outside. Palpation often can shown extremely promising results in horses with
reveal sensitivity at the site on forelimbs, but interpreta­ chronic hindlimb PSD as these horses are believed to
tion can be difficult. Flexion tests can be positive espe­ have a neuropathy accompanying the compartmental
cially carpal flexion test and spavin test, which can syndrome created by the enlargement of the ligament.
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mislead the diagnostician. Both fasciotomy and neurectomy are believed to reduce
Diagnosis is made using diagnostic analgesia: either the compartmental compression: directly with the fasci­
direct infiltration of the ligament origin or specific nerve otomy and indirectly by the neurectomy as it causes
blocks. If subtle or no obvious lameness is present, using atrophy of the muscular fibers within the ligament,
bilateral nerve blocks and reevaluating the horse for a resulting in a reduction of the cross‐sectional area.
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change in its freedom of movement or seeking the help Neurectomy of the deep branch of the lateral palmar
of an experienced rider to better evaluate the horse’s nerve has also become increasingly used in recurrent
ability to perform particular tasks may be necessary front suspensory cases.
(especially for dressage horses) to aid diagnosis. Suspensory branch injuries often have an acute onset.
Analgesia of the lateral palmar nerve at the level of Enlargement, heat, and pain to palpation are usually
medial aspect of the accessory carpal bone in the fore­ features of the early stages. Definitive diagnosis is made
limb and perineural injection of the deep branch of the using ultrasonography and periligamentous fibrous tis­
6
lateral plantar nerve in the hindlimb are gaining popu­ sue; core lesions or enthesiopathy at the insertion on the
21
larity as they are easy to perform and seem to decrease proximal sesamoid bones can be seen. Rest and con­
the incidence of unintentional analgesia of the carpo­ trolled exercise programs usually result in improvement.
metacarpal and TMT joints. Especially in the hindlimbs, Laser therapy seems to help reduce clinical signs. Large
the differentiation of distal hock pain and suspensory core lesions could be treated with splitting or intrale­
desmitis can be difficult. Performing a tibial nerve block sional injections. Enthesiopathies respond well to ESWT.
can help differentiate between the two as it would theo­ In some cases, the branch lesions communicate with the