Page 67 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

42 CHAPTER 1

VetBooks.ir Bilateral cases are common and affected foals adopt 1.73
a slightly bowlegged, over at the knee stance. They
may knuckle forward at the fetlock when walking.
Palpation of the swelling may reveal tendon rupture.
Radiography and ultrasonography can confirm the
presence of hypoplastic carpal bones and partial/
complete tendon rupture.
In most foals, rupture of the CDE tendon heals
spontaneously, without need for specific treatment.
However, in cases in which the condition is second-
ary to, or accompanied by, other orthopaedic prob-
lems, such as hypoplastic carpal bones or flexural
deformities, appropriate management is indicated.
The prognosis is good provided concurrent flexural
deformities are correctable.

CONTRACTED FOAL/LIMB SYNDROME

Contracted foal/limb syndrome describes a variety
of combinations of congenital appendicular and
axial contractures and curvatures that are uncom-
mon, but well recognised. The term includes
arthrogryposis (deformity of the limbs character- Fig. 1.73 A foal suffering with contracted foal
ised by curvature of the limbs, multiple articular syndrome, which was euthanased immediately after
rigidities and dysplasia of the muscles), torticollis birth. There is a wry nose, neck torticollis, distal limb
or ‘wry neck’ (lateral bending and rotation of the hyperextension and carpal flexural deformity visible in
cervical spine), scoliosis (lateral deviation usu- this view.
ally involving the last part of the thoracic and
first part of the lumbar spine) and lordosis and
kyphosis (ventral and dorsal curvature of usually POLYDACTYLY AND ADACTYLY
the last part of the thoracic and first part of the
lumbar spine). In addition, there may be varying Polydactyly and adactyly are both rare. Polydactyly
degrees of flexural deformity involving the car- is defined as the occurrence of more digits than
pus, MCP/MTP joints and, sometimes, the tarsus, normal for a given species. A dominant hereditary
and asymmetric formation of the cranium or ‘wry transmission with incomplete penetrance has been
nose’ (Fig. 1.73). Attenuation (thinning of the ven- postulated. The extra digit in horses can be terato-
tral abdominal wall or even visceral eventration) logical where duplication is distal to the fetlock joint,
is present in some cases of severe scoliosis. The resulting in two completely separate digits articulat-
condition may be due to unfavourable, restrictive ing with a third metacarpal bone, which may or may
uterine conditions and no evidence of a genetic not be divided distally (Figs. 1.74, 1.75). The more
aetiology has been described. If the deformities common atavistic (‘developmental’) form involves
are mild, affected foals can develop normally given an extra digit on the medial aspect of the forelimb
time and adequate nursing care. In more severe that fully articulates with a fully developed second
cases, surgical correction may be attempted, but metacarpal bone. Presentation is usually unilateral
if multiple abnormalities are present, euthanasia is in a forelimb, but bilateral forelimb and involvement
indicated. of all four limbs have been described. The atavistic
form is managed successfully by surgical resection of