SAEVA Congress 2018 Proceedings | 12-15 February 2018 | ATKV Goudini Spa
The site of skin penetration is located at the intersection of imaginary lines
drawn between the cranial borders of the atlas and along the dorsal
midline.
Palpate the wings of the atlas and define the site of skin penetration. The
needle is normally aimed at the lower jaw or lips (perpendicular to the
cervical vertebrae) usually with the bevel rostral. The wrist of the hand
advancing the needle should be rested on the occipital area or dorsum of
the neck so the needle can be advanced slowly with steady pressure. An
initial thrust is often helpful to advance the needle the first inch through the
thick skin and funicular part of the ligamentum nuchae.
The needle is advanced until the dorsal atlanto-occipital
membrane and cervical dura mater are penetrated. These tissues, being
stretched with flexion of the head, often give rise to a “popping” sensation when
penetrated. During insertion of the needle, the stilette should be withdrawn
whenever such a sensation felt or whenever it is felt a sufficient depth has been
reached. CSF appearing at the hub of the needle will indicate a successful
procedure. If no spinal fluid appears, the needle is rotated 90 degrees and if this
is unsuccessful, the stilette is replaced and the needle advanced further.
In adult horses, the depth at which the subarachnoid space is entered and
CSF obtained is normally between 2 and 3 inches. This depends on the
size and weight of the horse, angle of insertion of the spinal needle, and
degree of flexion of the atlanto-occipital joint. The needle generally should
not be advanced without the stilette in place to prevent damage to neural
tissue.
b. Lumbosacral Collection
Advantages: can be done as a standing procedure; generally less risk to
the horse
Disadvantages: may be difficult to obtain fluid; horse may kick or buck during the
procedure even if sedated
6.0 inch 18 gauge thin wall needle with fitted stilette (Occasionally, a
special 8 or 9 inch spinal needle will be required on very tall horses. A 3.5
inch 18 or 20 gauge spinal needle can be used in ponies and foals up to
approximately 12 hands)
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