Page 1063 - Adams and Stashak's Lameness in Horses, 7th Edition

Occupational‐Related Lameness Conditions 1029

can make a significant improvement, along with correc­ to decrease perineural inflammation. If following 60 days
tive farriery, in derotating the distal phalanx. Regardless of conservative management no improvement in clinical
VetBooks.ir draft horses is guarded to poor and is considered to be suprascapular nerve can be considered. The surgical
signs has been observed, surgical decompression of the
of the treatment chosen, the prognosis for laminitis in
technique has been described previously and is not
worse than for light breed horses.
detailed here. The surgical success rate has been
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Osteoarthritis of the Distal and Proximal reported as favorable. However, muscle atrophy can
Interphalangeal Joints persist in some cases, even though subluxation of the
shoulder joint and mechanical lameness resolves. The
OA of the distal (low ringbone) and proximal inter­ prognosis for conservatively treated horses is fair to
phalangeal (high ringbone) joints is not unusual. The good, whereas the prognosis for horses treated with sur­
greatest risk factor is a combination of large body size gery is guarded. Horses that return to use should be
and work‐related activities that pull and twist the lower monitored carefully for proper fitting of the collar to
limb. Radiographic evidence of ringbone is not unusual prevent recurrent suprascapular nerve injury.
and may not be responsible for signs of lameness. The
radiographic findings are similar to those found in other
breeds of horses. Mild cases of ringbone can be managed Osteoarthritis of the Lower Hock Joints
successfully with conservative management consisting of OA of the tarsometatarsal or distal intertarsal joints
corrective shoeing, NSAIDs, and intra‐articular injection. (bone spavin) is a common cause of hindlimb lameness
Moderate to severe cases of high ringbone that do not in competitive draft horses, especially in show horse
respond to conservative management should be consid­ hitches. Intra‐articular anesthesia of the lower hock
ered for pastern arthrodesis. In draft horses, pastern joints is indicated, and the author recommends using
arthrodesis should include at least two lag screws and mepivacaine in both the DIT and TMT joints to confirm
locking plate application to ensure a strong enough con­ the diagnosis. It is not unusual for affected horses that
struct to avoid cyclic fatique. 15,16 Pastern arthrodesis is appear lame in only one limb during baseline evaluation
performed less commonly in draft horses than light breed to become lame in the contralateral limb following suc­
horses, primarily because of the cost as well as anesthetic cessful intra‐articular anesthesia of the originally lame
concerns related to their large body size. Most owners limb. Radiography is not required but is helpful to
typically opt for retirement from exercise or use these determine the amount of radiographic change present
horses for breeding. The prognosis for ringbone in draft and establish a baseline for future examinations.
horses is favorable in mild to moderately affected horses. Mildly affected horses can be managed with correc­
Severely affected horses can only be successfully managed tive farriery and NSAID therapy. Corrective farriery can
with pastern arthrodesis, with a fair to good prognosis. include a square or rolled toe shoe with a 2°–3° heel
Osteoarthritis of the distal interphalangeal joint in elevation. The toe of the hoof should be trimmed short
mildly to moderately affected horses can be managed to aid break‐over. Moderately affected horses also
with a combination of corrective farriery and intra‐ should be treated with intra‐articular injections of corti­
articular injections. Surgical arthrodesis for severely costeroids. The author prefers methylprednisolone ace­
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affected horses may be considered, but most owners tate for injection into the DIT and TMT joints. Ethyl
reject this for financial reasons. 2,25 Palmar digital neu­ alcohol also can be used for intra‐articular injection to
rectomy also can be considered. The prognosis for distal facilitate bony fusion of the lower hock joints. Ethyl
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interphalangeal OA is lower than for proximal inter­ alcohol also is neurolytic, and injected horses frequently
phalangeal joint OA. are more comfortable following intra‐articular injec­
tion. Those that do not respond to intra‐articular injec­
Suprascapular Nerve Injury tions can be considered for surgical fusion of the lower
hock joints. The author currently prefers to perform sur­
Suprascapular nerve injury, or shoulder sweeny, is gical ankylosis with intra­articular drilling alone. 31
caused by direct trauma to the suprascapular nerve. This The prognosis for conservatively treated horses is fair
condition is not uncommon in draft horses because of to good, with the majority responding satisfactorily. In
repetitive injury to the suprascapular nerve from ill‐fit­ the author’s experience, fewer than 5% of horses diag­
ting collars. Clinical signs of shoulder sweeny include nosed with OA of the lower hock joints require surgery.
muscle atrophy of the supraspinatus and infraspinatus The prognosis following surgery is good, with most
muscles, subluxation of the shoulder joint, and lame­ horses improving.
ness. Nevertheless, all affected horses should have radio­
graphs of the shoulder to rule out traumatic injury,
including fracture of the supraglenoid tubercle or proxi­ Stringhalt
mal humerus. The clinical signs of this type of fracture Stringhalt is caused by hyperactivity of the lateral
and shoulder sweeny can be similar. Horses with clinical digital extensor (LDE) muscle. Causes include trauma to
signs of suprascapular nerve injury but no radiographic the LDE tendon, peripheral neuropathy, ingestion of
abnormalities should be treated conservatively for at toxic plants, and idiopathic causes. 4,14,28 The classical
least 60 days before deciding on surgical decompression clinical sign for stringhalt is hyperflexion of the hindlimb
of the suprascapular nerve. with the limb being quickly moved toward the abdo­
Conservative management consists of stall rest and men while walking or trotting. Clinical signs alone can
NSAID therapy if needed. Acute cases of shoulder be used to make the diagnosis. The only conservative
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sweeny can be administered corticosteroids and NSAIDs treatment for stringhalt is administration of phenytoin