Page 361 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

336 CHAPTER 1

VetBooks.ir 1.658 1.659

Fig. 1.658 Oblique radiograph of the fetlock Fig. 1.659 Mediolateral radiograph (non-weight bearing)
region of a horse with chronic oblique DSL of the digit of a 4-year-old steeplechase racehorse. Multiple,
desmopathy showing entheseophytic new bone irregular bone fragments are present in the soft tissues
production at the distal border of the medial PSB palmar to P1 (arrowheads). The palmar process of P2 is
(arrow) and ectopic mineralisation within the irregular and truncated (red arrow). This was a complete
soft tissues in the area of projection of the ODSL avulsion fracture of the middle scutum with proximal
(arrowhead). displacement of the SDSL. Note the articular surface
fragmentation at the dorsal aspect of the PIP joint (yellow
arrow), due to overextension.

Differential diagnosis Radiography
Tenosynovitis; DDF tendonitis; tendonitis of the Radiography should be performed in all cases to
branches of the SDFT; basilar fracture of a PSB; dis- look for remodelling (entheseopathy) at the liga-
tal SL branch injuries; digital palmar/plantar annu- ments’ insertion sites, particularly at the base of
lar ligament injuries. the PSBs (Fig. 1.658) or on P1, and to rule out
other associated sesamoid bone lesions (fractures,
Diagnosis displacement, osteitis) (Fig. 1.659). Roughening
Clinical examination of the bone or marked new bone production over
Lameness is always present and varies in degree the palmar sagittal aspect of the distal third of the
depending on chronicity and severity. With severe proximal phalanx diaphysis often indicates enthe-
tears and ruptures, lameness is always non-weight seous new bone around the insertion of the two
bearing. In some cases, subtle to marked swelling is ODSLs (Fig. 1.660). This is considered to be an
palpable in the region, but often there are no spe- incidental finding, not usually associated with des-
cific local signs. Lameness is abolished by abaxial mitis or lameness. PIP joint subluxation involves
sesamoid nerve blocks; it may be diminished or abol- damage to the middle scutum (palmar/plantar
ished with a palmar digital nerve block or intrathecal capsule of the PIP joint), SDSL and/or SDFT
anaesthesia of the digital sheath. insertion branches. Rarely, avulsion fracture of