46TH
ANNUAL
CONGRESS
OF
THE
SAEVA
SKUKUZA
16-‐20
FEBRUARY
2014
103
L1-L3 before innervating peritoneum, all three muscular layers (internal abdominal
oblique, external abdominal oblique and rectus abdominis muscles) and skin of the
abdominal wall.
Procedure:
The patient should be adequately restrained and sedated prior to performing the
block. The area at the level of the transverse processes should be surgically
prepared. Spinal nerve L2 is first nerve to be desensitized. A technique for locating
the transverse process requires determination of the caudal most point of the last
rib. An imaginary line is drawn from this point to the dorsal midline. A second line is
drawn parallel to the dorsal midline 5-6cm lateral to the dorsal midline. Where he
two lines meet is the transverse process of L3. In large horses a 14G needle is
generally placed first to facilitate easy placement of the spinal needle (18 G 15cm)
afterwards. The 14 G needle is advanced onto the transverse process. Once contact
has been made the needle is removed and the spinal needle is advance through the
tract created. The spinal needle is advanced over the cranial margin of the transverse
process and ventral through the intertransverse ligament. Once penetrated the local
anaesthetic is deposited after aspiration for accidental blood vessel penetration. This
is repeated for L1 spinal nerve 6-7cm cranial to previous site of needle placement.
For T18 spinal nerve the transverse process of L1 vertebrae can be difficult to
palpate as it is much shorter than L2. In this instance the needle is placed at a site
equidistant from rib T18 and transverse process of L2. There after the procedure is
the same.
Figure5: Schematic illustration demonstrating needle placement with respect to the tranverse
process and the spinal nerve pathway. . (Moon & Suter 1993. Equine Vet J. 25(4) 304-308)
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