Page 1113 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

1088 CHAPTER 10

VetBooks.ir in the syndromes that result from trauma, depend- ptosis and excessive sweating in the area that has
become denervated.
ing on the area affected and the severity of the lesion.
Cervical spine Thoracolumbar (T3–L2)
A recumbent horse with a spinal cord lesion at C1– Lesions of T3–T6 may cause paraplegia or parapa-
C3 has difficulty raising their head off the ground, resis and ataxia. A paraplegic horse that ‘dog sits’
whereas a recumbent horse with a lesion at C4–T2 usually has a lesion caudal to T2. Most animals with
should be able to lift the head and cranial neck. If the thoracic spinal cord injury have normal to exagger-
lesion is unilateral, the horse will be able to lift their ated spinal reflexes and hypertonia of the hindlimbs.
head when the affected side is closest to the ground. Conscious proprioceptive deficits are apparent in
Cervical spinal lesions may result in tetraplegia, or the hindlimbs. Some degree of asymmetry may be
present as tetraparesis and ataxia. Spinal cord lesions present with spinal cord trauma, but signs are almost
in C1–C6 will result in muscle tone and spinal reflex always bilateral. The forelimbs should be unaf-
responses typical for a UMN lesion: normal to fected. The bladder may show evidence of UMN
increased muscle tone, hyperreflexive spinal reflexes dysfunction. The level of hypalgesia on the neck
(panniculus, triceps and biceps) in all limbs, and or back indicates the cranial extent of the lesion. In
inability to empty the bladder due to increased ure- the early post-trauma phase, a region of hyperesthe-
thral sphincter tone (known as a ‘UMN bladder’). sia may be detected just cranial to the lesion. Strip
patches of sweating may occur when thoracolumbar
Cervicothoracic spine (C6–T2) spinal nerve roots are damaged. Whole-body sweat-
Lesions within the brachial intumescence result in ing, seen frequently in horses with a broken neck or
LMN forelimb signs (hypotonia and hyporeflexia) back, may be due to involvement of pain pathways
and UMN hindlimb signs (hyperreflexia and hyper- and sympathetic spinal cord pathways (Fig. 10.43).
tonia). If only the white matter is affected, and grey
matter spared, at this location then there could be Lumbar spine
normal forelimb tone. Conscious perception of Lesions at L1–L3 result in normal or hypertonic
pain may be reduced in all four limbs, and signs and hyperreflexic hindlimbs, and lesions at L4–S2
of a UMN bladder may be present, as with C1–C6 may result in hypotonia and hyporeflexia of the
lesions. Grey matter lesions between T1 and T3 may hindlimbs. The bladder is distended, but sphinc-
result in Horner’s signs (a loss of sympathetic inner- ter tone is normal. Tail and anal tone are normal
vation to the head) including miosis, enophthalmus, (Figs. 10.44, 10.45).

10.43

Fig. 10.43 A markedly
displaced fracture of the
thoracic spine secondary to
a high-speed collision.