Page 583 - Adams and Stashak's Lameness in Horses, 7th Edition

Lameness of the Distal Limb 549

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A B

Figure 4.130. Radiographs of the fetlock in two different horses demonstrating mild sesamoiditis (A) and moderate sesamoiditis (B) with
increased number of the vascular channels in the lateral proximal sesamoid bone (arrows).

Nuclear scintigraphy typically indicates increased of concurrent injury to the SL and the DSLs. In yearling
radiopharmaceutical uptake (IRU) in the region of the racehorses, enlarged vascular canals identified on radio-
sesamoid bones, but the uptake is usually less than what graphs have been associated with fewer race starts and
would occur with a fracture. Ultrasound of the SL and reduced earnings compared with horses with normal
DSLs may be useful, but many horses may have no vascular canals. Young racehorses with abnormal sesa-
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abnormalities in the ligaments in the acute phase. moid bones should also be monitored closely for future
However, subclinical SL branch change has been adjacent SL branch injuries that may occur. 34,71
reported in Thoroughbred yearlings with evidence of
sesamoiditis suggesting that ultrasound examination
should be performed in all affected horses. 71 AXIAL OSTEITIS/OSTEOMYELITIS
OF THE PROXIMAL SESAMOID BONES
Treatment Etiology
If heat, pain, and swelling are detected at the bone or Osteitis/osteomyelitis of the axial border of the proxi-
suspensory insertion, then efforts should be made to mal sesamoid bones is an uncommon cause of lameness in
reduce the inflammation. Both topical and systemic anti‐ horses. The cause remains unknown and speculative with
inflammatory medications may be used. Rest from perfor- vascular, infectious, and traumatic etiologies implicated.
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mance until soundness at the trot is achieved followed by The condition is specifically associated with the intersesa-
slow increasing duration and intensity of exercise allows moidean ligament within the apical to midbody axial mar-
the bone to continue to remodel and strengthen. gins of the sesamoid. The condition has occurred in
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Importantly, the exercise must be kept below the level that horses with septic tenosynovitis of the digital sheath, sep-
would reinjure the bone. Similar to other SL injuries, con- tic bacterial arthritis of the fetlock, and secondary to an
valescence is long (6–8 months), and injury often recurs Aspergillus fungal fetlock infection. 80,103 In another report,
when horses return to full work. In chronic stages, blister- the clinical signs and radiographic lesions were suggestive
ing and ESWT have been used but with equivocal success. of sepsis, although histology of lesions revealed infarction
Young Thoroughbred horses with suspensory branch inju- and necrosis as well as osteoporosis and chronic inflam-
ries and concurrent sesamoid inflammation treated with mation in the intersesamoidean ligament. 16
PRP at the junction between the bone and the ligament
were more likely to start at least one race during their 2‐
year‐old racing year than horses treated with saline; but Clinical Signs and Diagnosis
this benefit did not extend into their 3‐ and 4‐year‐old Horses typically present with a consistent lameness
racing years. 34 that may be severe (often lame at the walk). In one report,
lameness ranged from 2 to 5 out of 5 (mean 4 out of
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Prognosis 5). In another report of 12 Friesian horses, all lesions
were in the hindlimb, and lameness was acute and
The prognosis for return to full athletic performance severe. Radiographs usually reveal bone lysis at
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free of lameness is guarded to unfavorable, depending the attachment of the intersesamoidean ligament
upon the amount of periosteal reaction and new bone primarily at the midbody and apical regions with varying
growth that occurs on the sesamoid bones and the extent degrees of joint effusion (Figure 4.131A). A single or
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