Exam 1 - Equine Nerve Blocks Flashcards

1
Q

how can you avoid potential complications associated with nerve blocks?

A

proper restraint of the horse decreases the likelihood of needle breakage

proper prep of the site - avoid infecting synovial structures

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2
Q

when should you use diagnostic anesthesia in an equine lameness case?

A

to identify painful region when either obvious pathology is lacking or there is more than one lesion present

to direct diagnostics & imaging

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3
Q

which medication used for nerve blocks is least safe for joints?

A

bupivacaine - chondrotoxic

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4
Q

how should you prep a patient for a regional nerve block?

A

quick prep - chlorohex/betadine for 3-5 minutes

removes surface debris

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5
Q

what nerves are blocked by a PD block?

A

palmar/plantar digital nerves

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6
Q

how do you place your needle for a PD nerve block when taking into consideration the neurovascular bundle?

A

vein is most lateral

artery is middle

nerve is medial

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7
Q

where are your landmarks for a PD nerve block?

A

feel for the neurovascular bundle above the hoof cartilages

insert the needle distally about 1cm above the hoof cartilages

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8
Q

what structures are reliably anesthetized by a PD block?

A

navicular bone, navicular bursa, navicular apparatus, DDFT, frog, 1/3-1/2 sole, parts of the PIP/DIP, & skin

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9
Q

what is the benefit of performing a midpastern PD block?

A

allows for desensitization of the entire foot including the PIPJ

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10
Q

what nerves are desensitized by an abaxial sesamoid block?

A

palmar digital nerves at or near the proximal sesamoid bones

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11
Q

what structures are anesthetized by the abaxial sesamoid block?

A

everything in the PD block

DIPJ, PIPJ, distal sesamoidean ligaments, dorsal branches of the suspensory ligament, DDFT, SDFT, & +/- MCP joint

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12
Q

what landmarks are used for an abaxial sesamoid block?

A

palpate the neurovascular bundle at the abaxial border of each proximal sesamoid bone

direct the needle distally at this level

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13
Q

if doing a palmar/plantar PD block, what region do you expect to block? what else was potentially blocked?

A

palmar/plantar 1/3-1/2

most of the foot

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14
Q

if doing a palmar/plantar PD block including the dorsal branches, what region do you expect to block? what else was potentially blocked?

A

from coronary band distal

same as PD

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15
Q

if doing a abaxial sesamoid block, what region do you expect to block? what else was potentially blocked?

A

from proximal pastern distal

complete foot, pastern region, & fetlock joint

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16
Q

what nerve block is being done in this photo?

A

PD nerve block

17
Q

what nerve block is being done in this photo?

A

abaxial sesamoid block

18
Q

what block is being done in the photo? what are your landmarks?

A

coffin (DIP) joint

thumbs width above the coronary band & thumbs width off dorsal midline to either side to find a depression adjacent to the extensor tendon where the needle is inserted either medially or laterally angling to the opposite coroner of the foot

19
Q

what is blocked in a DIP joint block?

A

coffin joint, parts of the coffin bone, collateral ligaments of the coffin joint, impar ligament, & navicular bone

overtime, it diffuses out to block the navicular bursa & caudal port of the foot (coffin bone & soft tissue structures in the heel)

20
Q

what is blocked in a navicular bursa block? what are the landmarks used?

A

navicular bursa, navicular bone, & caudal portions of the heel

spinal needle is inserted between the heel bulbs parallel to the sole of the foot

21
Q

what is blocked in a PIP block? what are the landmarks used?

A

pastern, & with time diffuses out & also as a PDN block

find the widest part of the long pastern bone & aim the needle slightly below it

22
Q

what nerves are blocked in a low 4 point? what are the landmarks used?

A

medial & lateral palmar & palmar metacarpal/metatarsal nerves

immediately distal to the distal ends (buttons) of metacarpal II & IV for the palmar metacarpal/metatarsal nerves & 1cm proximal for the palmar nerves

23
Q

what structures are blocked in a low 4 point?

A

entire fetlock & all structures distal to it but may miss some skin on the dorsal fetlock

24
Q

what structures are blocked in a high 4 point?

A

deep structures of the metacarpus & all structures distal to the block with the exception of the origin of the interosseus m.

25
what nerves are blocked in a high 4 point? what are the landmarks used?
medial & lateral palmar & palmar metacarpal/metatarsal nerves same as low 4 point but performed just distal to the carpus
26
what nerves are blocked in a lateral palmar block? what are the landmarks used?
lateral palmar nerve proximal to its deep branch & medial and lateral palmar metacarpal nerves medial to the accessory carpal bone
27
what structures are blocked in a lateral palmar?
origin of the interosseus m. & other deep structures of the palmar metacarpus/metatarsus
28
what nerve block is pictured here?
low 4 point
29
what nerve block is pictured here?
high 4 point
30
what sort of anesthetic agent would you use to perform a lameness exam & why?
mepivicaine - provides moderate duration of activity (~2 hours), rapid onset, ~10 minutes, & relatively non-irritating lidocaine is used if you want it to wear off faster but may be more irritating bupivacaine is used for long lasting blocks - treating laminitis or pain control
31
how would you block out the entire foot?
abaxial sesamoid nerve block - check for sensation at the dorsal coronary band to make sure the entire foot is blocked
32
what are 2 blocks you could use to block the fetlock?
low 4 point & fetlock joint block
33
what block would you use to block out the suspensory ligament?
regional infiltration, high 4 point, or lateral palmar
34
how would you evaluate a horse for bone spavin?
inject the tarsometatarsal +/- distal intertarsal joints
35
what are 2 ways you could block the tibiotarsal joint?
intra-articular block or tibial & peroneal nerve blocks
36
there are 3 joint pouches in the stifle - do you need to block all 3 separately?
usually the medial femorotibial & femoropatellar joints communicate but only 1 in 4 lateral femorotibial joints communicate with the femoropatellar joint
37
there are 3 joint pouches in the carpus - do you need to block all 3 separately?
intercarpal & carpometacarpal joints communicate
38
there are joint pouches associated with the hock in the horse - do you need to block all 3 separately?
sometimes the tarsometatarsal & distal intertarsal joints communicate proximal intertarsal & tibiotarsal joints usually communicate
39
what risks are associated with local anesthetic procedures?
local irritation & swelling risk of creating a septic joint hemorrhage breaking a needle off