Page 66 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

Musculoskeletal system: 1.2 The foal and developing animal 41

VetBooks.ir plantar/palmar aspect of the pastern and fetlock RUPTURE OF THE COMMON
DIGITAL EXTENSOR TENDON
contacts the ground (Fig. 1.70).
Many cases resolve spontaneously as muscle
tone and ligament strength improves post partum. Rupture of the common digital extensor (CDE) ten-
This process can be encouraged by careful exercise. don is relatively uncommon. It usually affects both
Corrective foot trimming of the heel to provide a forelimbs and is usually present in combination with
flat weight-bearing surface and eliminate a ‘rocker other musculoskeletal defects, in particular carpal
heel’ effect is useful. A light protective bandage to and metacarpophalangeal flexural deformities, hypo-
protect the heel/pastern/fetlock from trauma can plasia of cuboidal bones and underdeveloped pecto-
be provided, but too much support exacerbates the ral muscles. The condition may be inheritable and
condition. a higher incidence has been reported in Arabs and
Heel extension shoes should be used in unresolv- Quarter horses. In Thoroughbred foals, rupture
ing or severe cases (Fig. 1.71). Surgical manage- almost always follows carpal contracture and may be
ment as a salvage procedure, with tendon shortening a direct physical consequence of the contracture.
Z-plasties, has been described, but is rarely neces- Swelling of the tendon sheath over the dorso-
sary or used. lateral surface of the carpus is present (Fig. 1.72).

1.71 1.72

Fig. 1.71 Older Thoroughbred suckling foal Fig. 1.72 Two-week-old foal that presented with an
with a history of bilateral hindlimb distal joint acute onset of a dorsolateral distal radius fluid-filled
hyperextension that did not respond to conservative swelling (arrow) due to rupture of the common digital
treatment and was eventually treated with heel extensor tendon. This was not associated in this foal
extension shoes. with a flexural deformity.