Page 1117 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

1092 CHAPTER 10

VetBooks.ir 10.50 10.51

Fig. 10.50 Suprascapular
nerve injury secondary to a
collision with another horse.

Fig. 10.51 Radial nerve
paralysis.

is unable to bear weight on the limb and the foot Musculocutaneous, median, ulnar
is knuckled over at rest. Distal radial nerve lesions These nerves innervate the flexor muscles of the
will result in flexion of the carpus, fetlock and pas- elbow, carpus and digit. Dysfunction most com-
tern joints. The animal can support weight on the monly occurs as a result of brachial plexus inju-
affected limb if the metacarpus and distal limb are ries, but it can also be seen with spinal cord lesions
held in extension. The triceps reflex in affected involving the grey matter of the brachial intumes-
patients will be decreased to absent. Sensory deficits cence. Gait alterations can occur with injury to the
are variable between patients (Fig. 10.51). individual nerves, but these may disappear or be very
subtle after approximately 3 months. Ulnar neurec-
Brachial plexus tomy results in the most pronounced abnormalities,
Lesions of the brachial plexus can be caused by with decreased flexion of the carpus and fetlock, and
shoulder trauma, deep penetrating axillary wounds residual effects such as stumbling are common. The
and traction on fetal forelimbs during dystocia improvement that can be seen over time, particularly
relief. Nerves of the brachial plexus supply motor with musculocutaneous and median nerve injuries,
innervation to the biceps, coracobrachialis (mus- may be due in part to crossing of fibres from one
culocutaneous), pectoral, subscapularis and tri- nerve to the other.
ceps muscles, and therefore severe lesions result in
complete flaccidity of the forelimb, with the animal Femoral
unable to bear weight. Triceps and biceps reflexes are Femoral nerve paralysis can be caused by abscesses,
absent. Pectoral nerve dysfunction results in elbow tumours and aneurysms in the region of the exter-
abduction, and a dropped shoulder results from sub- nal iliac arteries, in addition to penetrating wounds
scapular nerve paralysis. Inability to flex the elbow, of the caudal flank. Fractures of the pelvis and
with hyperextension at rest, results from muscu- femur may be associated with femoral nerve damage
locutaneous nerve paralysis. Signs of radial nerve and in such cases the integrity of the nerve should
paralysis will also be present, as will complete desen- be determined before fracture repair. Damage to
sitisation of the entire forelimb. this nerve may also be associated with prolonged