Page 618 - Adams and Stashak's Lameness in Horses, 7th Edition

584 Chapter 4

(CSA), and straight hindlimb conformation is not Prognosis
present in a hindlimb injury. Trotting can begin after 8 The prognosis for acute forelimb PSD is good (greater
VetBooks.ir and the horse is sound at the trot in hand. A slow and than 80%) for return to full work in sport horses with
weeks if the lesion is reasonably improved on ultrasound
forelimb PSD following 3–6 months of rest and con-
controlled (saddle) or rein lunging exercise program can
continue until 16 weeks, when another ultrasound is trolled exercise. 22,100 For hindlimb lameness, the progno-
performed. If soundness persists and the lesion appears sis is significantly worse with only 14%–69% of horses
healed on the 16‐week ultrasound exams, the horse’s returned to full athletic function without detectable lame-
22,38
exercise can increase. Total healing time is 8 months and ness. The wide variety of outcome with hindlimb PSD
return to full competitive performance may not be pos- may be related to the greater range and tendency for more
sible for 1 year. severe lesions, concomitant neuropathy and compart-
Recurrence of injury is greater in horses that have ment syndrome, and conformational issues that predis-
been inadequately rested and for abnormalities within pose the SL to greater stresses, such as dropped fetlocks
the hindlimbs. Balancing the foot, shoeing with egg‐bar and straight hocks. Recently, it was reported that neurec-
shoes, and using sport fetlock support bandages can tomy of deep branch of the lateral plantar nerve resulted
135
improve the flexor surface support. A more prolonged in an 80% return to performance for hindlimb PSD.
convalescent period is required if pain returns after Osteostixis of the proximal metatarsus at the origin of the
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exercise has begun. Use of oral glycosaminoglycans, sys- PSD in hindlimbs has also been reported. The presence
temic polysulfated glycosaminoglycans, and systemic of upright hindlimb (straight hock) conformation is over-
hyaluronic acid may have benefit, although unproven. represented in horses with hindlimb suspensory injury
Use of internal blisters, intralesional steroids, and miner- and may predispose the ligament to injury and recur-
alizing agents is contraindicated. rence—hence, the poor success rate for permanent resolu-
Regenerative medicine therapies consisting of ultra- tion of lameness. Another proposed reason for the poor
sound‐guided injection of bone marrow aspirate con- prognosis associated with hindlimb PSD is the develop-
centrate (BMAC), autologous mesenchymal stem cells ment of a “compartmental syndrome” resulting from the
(MSCs), or autologous platelet concentrates have shown limited space available between the prominent splint
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efficacy. 4,137 In one study of suspensory desmitis of the bones into which the inflamed SL can expand.
body, autologous platelet concentrate injection in Recurrence of PSD also relates to use. In one study,
Standardbred racehorses resulted in all nine cases return- dressage and show jumping horses had the highest
ing to racing with good performance, equal to peers in recurrence rate of PSD, 37% and 46%, respectively,
money earned. Surgical splitting, ultrasound‐guided compared with racehorses (27%), show hunters (19%),
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137
26
desmotomy and fasciotomy, and shockwave therapy 62,77 and field hunters (18%). In addition, the larger the SL
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have also been described for PSD injury that has signifi- lesion, the greater the chance of recurrence. Generally,
cant lesions on ultrasound or that does not respond as the recurrence of PSD after 1 year following successful
expected to confinement and medical management. treatment is low, but when it does occur, the prognosis is
Improvement in most horses occurs over 6 months of guarded for return to performance. The prognosis is also
treatment. Neurectomy of the deep branch of the lateral reduced when PSD is associated with other lesions such
plantar nerve with concurrent fasciotomy has a reported as tendinitis of the SDFT and DDFT or desmitis of the
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success of 77.8% of horses with PSD alone. However, in superior check ligament.
this study, all horses with concomitant straight hock The prognosis for avulsion fracture associated with
conformation and/or hyperextension of the fetlock the origin of the SL appears good for uneventful recov-
remained lame and horses with concurrent OA of the ery to full work after 3–6 months of rest and controlled
distal tarsal joints were reported to have a significantly exercise. Horses with evidence of exostoses developing
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worse prognosis following surgery (44.2%). However, around the splint bones, but in association with PSD,
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the surgery may be particularly useful in horses with may benefit from bone debridement after CT.
compressive damage to the lateral plantar nerve, which
can cause persistent lameness. 135 Degenerative Suspensory Ligament Desmitis (DSLD)
In suspensory desmitis of the branches, treatment of
concomitant disease of the fetlock, support bandaging, DSLD is a debilitating disorder thought to be limited
and a modified training program permits many horses to the SL of Peruvian Pasos, Peruvian Paso crosses,
to continue performing. Intralesional orthobiologic Arabians, American Saddlebreds, Quarter horses,
therapies described previously are also frequently per- Thoroughbreds, and some European breeds. It primarily
formed. Surgical removal of the distal splint fractures is affects the body and proximal aspects of the ligament
controversial and may not address the primary cause of and is often bilateral. Both forelimbs or both hindlimbs
lameness. can be involved, and frequently the disorder leads to
Horses with a dropped fetlock conformation have persistent incurable lameness requiring euthanasia.
lost suspensory support to the limb and are at high Many horses have excessive fetlock extension (drop-
risk of re‐injury or complete SL breakdown. Use of ping) on presentation, and horses with hindlimb involve-
support bandages and heel extension shoes, such as an ment often have the combination of straight hocks and
egg bar, are recommended. Many of these horses are fetlock hyperextension (Figure 4.163). Affected horses
retired. In addition, horses with DSLD often have a often have palpable enlargement and pain of the SL. The
bilaterally dropped fetlock conformation as part of diagnosis is usually made based on patient signalment
the presenting clinical picture, suggesting severe dam- and history, clinical examination, and ultrasonographic
age to the SL. abnormalities within the affected SL. Treatment is