Page 1116 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

Nervous system 1091

VetBooks.ir 10.48 10.49

Fig. 10.48 Use of a sling in the management of a Fig. 10.49 A tail abscess that resulted in severe
yearling with a fracture at C7. osteomyelitis of the caudal vertebrae.

TAIL INJURIES muscles. Early denervation is characterised by an
outward bowing of the scapulohumeral joint when
Lifting heavy horses by the tail may result in dam- the animal is weight bearing. This is followed by
age to coccygeal nerves. Sacrococcygeal dislocation neurogenic atrophy over a number of months,
results in severe stretching and tearing of the cauda resulting in prominence of the scapular spine. Some
equina and will often result in permanent neurologi- horses circumduct their limb during protraction to
cal dysfunction. If there is no luxation of the tail, avoid dragging the toe. These horses are unsound
the lesion is more likely to be a neuropraxia and this for athletic purposes. This condition is commonly
should resolve with time. known as ‘Sweeney’ (Fig. 10.50).

PERIPHERAL NERVE DISORDERS Radial
The radial nerve provides motor innervation to the
Definition/overview extensor muscles of the forelimbs. It is most vulnera-
Trauma is the primary cause of peripheral nerve ble to trauma over the lateral aspect of the elbow joint.
disorders, but injections, tumours, abscesses Injury most commonly arises from direct trauma to
(Fig. 10.49) or parasitic invasion of the nerves can the nerve during prolonged anaesthesia or recum-
also be seen. bency without sufficient padding. Radial paralysis
can also accompany humoral fractures or fractures
Aetiology/pathophysiology of the first rib, and function of this nerve should be
Suprascapular evaluated before fracture repair because of the poor
Trauma to this nerve commonly occurs when horses prognosis that accompanies radial nerve damage.
collide with each other or, more commonly, with The limb position varies depending on the location
inanimate objects. Tension on the nerve can also of the lesion in the radial nerve. A lesion at, or near,
be caused by the animal stumbling with the limb the elbow joint results in a high radial nerve paraly-
stretched backwards. Damage to the nerve results sis, with a dropped elbow, failure of limb protrac-
in paralysis of the infraspinatus and supraspinatus tion and flexion of all distal limb joints. The animal