Diagnostics

Question 1

Site for abdominocentesis (2)

Answer 1

1) Ventral midline caudal to the umbilicus (avoids omentum covered C1 cranial to the umbilicus)
2) Paracostal approach - 1cm dorsal and 3cm caudal to the CC junction of the last rib (alpacas) or 2cm caudal and 5cm dorsal to the CC hunction of the last rib (llamas)

Question 2

Sites for jugular venipuncture in SACs (2)

Answer 2

1) Cranial neck - caudal to the raums of the mandibleand parotid gland, before the vein courses dorsally to lie deep to sternomandibularis tendon

Vein and artery are seprated by omohyoideus mm in this location, but skin is thickest here (1cm)

2) Caudal neck - caudomedial to the ventral process of C6

Skin is thinner here although aa and vv are close together so may be incr risk of arterial injection

Usually both done on the right but not sure why

Vs camels where distension of the upper 1/3 can be seen like the horse

Question 3

Preferred site for thoracocentesis

Answer 3

6-7 ICS, 10-15cm dorsal to the sternum or 2-4cm dorsal to the costochondral junction for fluid, more dorsal position for air - 8-9 ICS 25cm from the dorsum

14-16g catheter for fluid, go close to the cranial border of the caudal rib (intercostal vessels/nerves are at the caudal border of the ribs)

Question 4

Sites for CSF aspiration

Answer 4

1. AO space - necessitates GA. Head flexed, wings of the atlas palpated to locate narrowest width at cranial border. Draw a line from wing to wing and penetrate the skin on midline perpendicular to the vertebrae (same as horse). Needle will penetrate funicular ligamentum nuchae & then dorsal atlantooccipital membrane. The cervical dura mater lies closely adjacent to the membrane, and with the head held in tight flexion, the membrane and dura will be tense. The needle should penetrate the subarachnoid space with an audible or palpable “pop.” The depth of the subarachnoid space is approx 4cm at this location
2. Lumbosacral space: landmarks are tuber coxae & DSP of L7. Site is 2cm caudal to L7 DSP (sacral DSPs are short so much harder to palpate), on midline. The interarcuate space is large in this location - 2cm cranial caudal and 4 cm wide. Tissues penetrated are: skin, thoracolumbar fascia, interspinous ligament, interarcuate ligament, dura mater, and arachnoid. As for AO sample, never manipulate the needle without the stylet in. Occlude the jugulars if struggling. Can advance the needle through the conus medullaris of the cord (most distal bulbous expansion of the spinal cord) to the floor of the spinal canal. Then the needle should be withdrawn, 1mm at a time, until fluid flows. Depth of the subarachnoid space is 6 to 6.5cm in an adult llama and 2 to 2.5 cm in a neonate. The floor of the spinal canal is approximately 8cm in an adult and 3.5cm in a neonate.