Equine regional anaesthesia

Question 1

What are the 3 branches of the trigeminal nerve

Answer 1

Ophthalmic, maxillary & mandibular branches

Question 2

What do we anaesethise for eye/eyelid surgery

Answer 2

Periorbital region
5 sensory nerve blocks
Branches of ophthalmic nerve

Question 3

Label the periorbital region

Answer 3

Question 4

From where does the supraorbital nerve emerge

Answer 4

Supraorbital foramen (easy to palpate)

Question 5

Describe a retrobulbar nerve block

Answer 5

Needle to back of horses eye by curving spinal needle (can move cellular debris to back of eye in case of infection/neoplasia)

Can also go through supraorbital fossa at top of horses eye, straight spinal needle to back of eye)

Question 6

Describe a block of the maxillary branch

Answer 6

Branch runs into maxillary foramen & comes out of inferior orbital foramen (nerve can be blocked at either side)

Maxillary teeth: block from maxillary foramen

Skin of muzzle: in infraorbital foramen

Question 7

How can you find the infraorbital foramen in horses

Answer 7

Middle finger in naso-incisive notch

Thumb at rostral end of facial crest

Index finger falls into foramen

Question 8

Describe a block of the mandibular branch

Answer 8

Runs into mandibular foramen and out of mental foramen

For teeth block at mandibular foramen
- Have to triangulate position of maxillary foramen & insert long spinal needle from ventral surface
- Can work out approx. site by drawing cross. Horizontal line at level of occlusal surface of cheek teeth & other line straight down from lateral canthus of eye. Foramen is where lines bisect

Mental foramen block for soft tissues