Locoregional Nerve Blocks- Large Animal

Question 1

What species are auriculopalpebral blocks performed in?

Answer 1

Equine and bovine

Question 2

T/F: Auriculopalpebral blocks are sensory blocks ONLY.

Answer 2

False- only motor blocks, eyelids and cornea remain sensitive

Question 3

Where is the injection placed for an auriculopalpebral block in a horse?

Answer 3

Most dorsal point of the zygomatic arch

Question 4

Which muscle is paralyzed with auriculopalpebral blocks?

Answer 4

Obicularis oculi

Question 5

What does the supraorbital block effect?

Answer 5

Sensory to middle 2/3 of upper eyelid and palpebral motor

Question 6

Where is a supraorbital block injection placed?

Answer 6

Supraorbital foramen

Question 7

What is a supraorbital block used for?

Answer 7

Placement of sub-palpebral lavage catheter

Question 8

Is an equine retrobulbar block the same procedure as in small animal?

Answer 8

Yes

Question 9

Where is an infraorbital block placed?

Answer 9

At the exit of the infraorbital canal

Question 10

What area does an infraorbital block effect?

Answer 10

Exit of canal: Sensory to the upper lip and nose

Inside canal: teeth rostral to first molar, maxillary sinus, roof of nasal cavity

Question 11

What does a mental nerve block do?

Answer 11

Desensitize the lower lip

Question 12

Why are caudal epidurals used in horses?

Answer 12

Because you don’t want to lose hindlimb motor function.

Question 13

What are some indications for a caudal epidural?

Answer 13

1. Control of rectal tenesmus
2. Obstetric procedures
3. Tail amputation, rectovaginal fistura repairs
4. Hindlimb procedures and pain

Question 14

Where are caudal epidurals placed?

Answer 14

First coccygeal space- first movable joint when tail is manipulated

Question 15

Should LAs be used in equine epidurals?

Answer 15

They can, but must limit spread cranially

Lidocaine 2% 6-8mL usually sufficient in an adult horse

Question 16

Can Alpha-2 agonists be used in equine epidurals?

Answer 16

Yes, more commonly used (xylazine and detomidine)

May cause systemic effects

Question 17

Can morphine be used in equine epidurals?

Answer 17

Yes- provides analgesia without risk of motor junction impairment

Often mixed with detomidine

Question 18

Should epidural catheters be used with local anesthetics in horses?

Answer 18

No- motor blockade

Question 19

How much lidocaine should be injected into the testicle for a castration?

Answer 19

Enough so that it feels firm- usually around 20mL

Question 20

Does a testicular injection provide cutaneous analgesia?

Answer 20

No

Question 21

When is inta-articular morphine typically used?

Answer 21

Analgesia and anti-inflammatory post-arthroscopy

Question 22

What is a peterson block?

Answer 22

Similar block as retrobulbar but is more difficult to perform.

Question 23

What nerves does a peterson block effect?

Answer 23

Oculomotor, trochlear, abducens, trigeminal

Question 24

T/F: Both retrobulbar and peterson blocks prevent blinking for several hours.

Answer 24

True- eyes should be lubricated and animals should be kept out of the sun/dust/wind until motor function returns

Question 25

Which nerves should be blocked for dehorning in cattle and goats?

Answer 25

Cattle- cornual branch of zygomaticotemporal

Goats- cornual branch of zygomaticotemporal and cornual branch of intratrochlear

Question 26

What are the techniques for a ruminant flank laparotomy?

Answer 26

Infiltration- Line block or inverted L block

Regional- proximal or distal paravertebral

Question 27

What is a line block?

Answer 27

Injecting LA subcutaneously along the incision line

Question 28

What is an inverted L block?

Answer 28

Injections of idocaine into the area dorsocaudal to the last rib and ventrolateral to lumber transverse processes

Question 29

Is the LA injected along the incision line in an inverted L block?

Answer 29

No

Question 30

what are some other names for a proximal paravertebral thoracolumbar block?

Answer 30

Farquharson, hall, or cambridge technique

Question 31

Which nerves are effected in a proximal paravertebral thoracolumbar block?

Answer 31

Dorsal and ventral branches of T13-L2

Question 32

Where is the injection placed in a proximal paravertebral thoracolumbar block?

Answer 32

3-5cm from dorsal midline

Question 33

What are signs of a successful proximal paravertebral thoracolumbar blockade?

Answer 33

1. Analgesia of skin
2. Increase skint temp
3. Spinal scoliosis towards desensitized side

Question 34

What are some disadvantages of a proximal paravertebral thoracolumbar block?

Answer 34

1. Technically difficult
2. Scoliosis may impair incision closure
3. Risk of penetrating great vessels
4. Loss of motor control if LA migrates to femoral

Question 35

Which nerves are effected by a distal paravertebral thoracolumbar block?

Answer 35

Dorsal and ventral branches of T13-L2 also transverse of L1, L2, and L4

Question 36

What are the advantages of a distal paravertebral thoracolumbar block versus proximal?

Answer 36

Lack of scoliosis and less risk of damaging blood vessels

Question 37

What are the disadvantages of a distal paravertebral thoracolumbar block?

Answer 37

Larger amount of local anesthetic and may be less effective

Question 38

What kinds of animals are lumbosacral epidurals used in?

Answer 38

Immature cattle, small ruminants, camelids, and pigs

Question 39

What drugs are used in lumbosacral epidurals for large animals?

Answer 39

Alpha-2 agonists

Question 40

T/F: Local anesthesia can be done on the teat to treat lacerations or other injuries.

Answer 40

True- ring blocks, inverted IV blocks, teat cistern infusion, IVRA

Question 41

Which nerves are blocked in order to anesthetize the udder?

Answer 41

Paravertebral block of L1-L3 or high caudal/LS epidural

Question 42

What kind of blocks are done to anesthetize the feet?

Answer 42

Ring block or IVRA