Local, Regional, and Spinal Anesthesia

Question 1

what local anesthetics are used in food animals?

Answer 1

Lidocaine is used the most often because it has about 1-2 hour duration with a 1-5 minute onset and is cheap.

Mepivacaine has the same onset as lidocaine and lasts 2-3 hours but is more expensive

Question 2

the toxic dose of lidocaine for cattle is __mg/kg and for small ruminants __mg/kg

Answer 2

10mg/kg for cattle and 5mg/kg for small ruminants

Question 3

what are some common procedures that local, regional or spinal anesthesia may be used for?

Answer 3

local: castration

regional: LDA, C- section

spinal: epidural/ C- section, dystocia, embryo transfer

Question 5

What are 4 of the common blocks for laparotomy’s?

Answer 5

Line block
Inverted L block
Distal paravertebral block
Proximal paravertebral block

Question 6

Line Block

Answer 6

A line block is used if you need to be fast (think c sections) and to block a specific area of the paralumbar fossa. To start you should insert a 18G spinal needle into the SQ, then the muscle layer and peritoneum all while pushing your drug continuously as the needle turns. In sheep and goats you should use an 18G or 20G needle.

Question 7

Line Block

Answer 7

A line block is used if you need to be fast and to block a specific area of the paralumbar fossa. To start you should insert a 18G spinal needle into the SQ, then the muscle layer and peritoneum all while pushing your drug continuously as the needle turns. In sheep and goats you should use an 18G or 20G needle.

Question 8

Inverted L block

Answer 8

This is a non- specific block that will create an area of anesthesia under/behind the inverted L by using a large volume of lidocaine (150-200mls). To start, you’ll insert in the SQ, then 45 degrees, and 90 degrees so you hit all of the layers and continuously inject. Typically an 18G 1.5 inch needle can be used for this. This could be used for DA sx, etc.

Question 9

is a line block or inverted L block more likely to cause a hematoma?

Answer 9

Line block

Question 10

Distal paravertebral block

Answer 10

The distal paravertebral block desensitizes the dorsal and ventral rami of the spinal nerves T13, L1, and L2 at the distal end of transverse processes L1, L2, and L4 by placing lidocaine dorsal and ventral to the transverse processes (10ml each site). To start you‘ll use a 1.5 inch 18G needle to hit the tip of the transverse process and then slip the needle above and below, using 60-120mls at the end.

Question 11

Proximal Paravertebral Block

Answer 11

The proximal paravertebral block desensitizes the dorsal and ventral nerve roots of T13, L1, and L2 spinal nerves as they emerge from the intervertebral foramen. First you’ll block the skin and muscle with an 18G, 1.5 inch needle. The needle will enter at the cranial edge of L1, L2, and L3 with a 14G needle being the guide and 18G 4-6 inch spinal needle placed through the cannula. Then you’ll pass the needle until it hits the transverse process and walk off the cranial edge and advance 1 cm into the inter transverse ligament depositing 6-10ml per site

Question 12

Caudal epidural anesthesia

Answer 12

Caudal epidural anesthesias goal is to block being the sacrum (start around C1) by using an 18G 1.5 inch needle and finding S5-C1 on midline. You’ll insert your needle into the intervertebral space and should hear negative pressure from the epidural space if you’re in the right place. Use this technique fro dystocias, embryo flushing, prolapses, etc.

Question 13

Typically what amount of lidocaine is used for an epidural in a cow? Small ruminants?

Answer 13

1ml/200lbs for cows and level out around 6-7mls

1ml/30-50lbs small ruminants

Question 14

High Volume Caudal Epidurals

Answer 14

These are used to block abdominal, udder, urogenital surgery and c-sections with the same technique as caudal epidurals just a higher volume. The dose is 4-6mg/kg (up go 8)

Question 15

Lumbosacral Epidurals

Answer 15

SWINE and small ruminants use these a lot. To start, you should use a spinal needle to block the skin and then inject just caudal to the last spinous process of L6. There is a palpable depression slightly caudal to a transverse line between the cranial prominences of the winds of the ilium on either side.

Question 16

Why is distal limb anesthesia performed and how?

Answer 16

Distal limb anesthesia can be used for debridement, deep digital sepsis, and generally animals that are extremely lame. You’ll use lidocaine and a tourniquet to keep it local to the distal limb, just make sure you remove the tourniquet in 45min to an hour

Question 17

What are the 2 blocks used for teat anesthesia?

Answer 17

Ring Block: curve needle to make ring around the base of the teat and insert 5-10mls of lidocaine

V-block: for localized lesions of the teat

Use a 22-25G needle for both

Question 18

Retrobulbar eye block

Answer 18

It’s a 4 point block that is easier to perform by using a 18G spinal needle to bend around the globe and insert 15-20ml of lidocaine at each site.

Question 19

Peterson Eye Block

Answer 19

Start by anesthetizing the skin and use 14G as a cannula then place an 18G spinal needle horizontall and caudally until it has contact with the coronoid process. Then manipulate rostrally around the coronoid process to the pterygopalantine fossa at a depth of 3-4 inches and deposit 15-20mls of lidocaine.

This blocks the oculomotor, trochlear, abducens and trigeminal (all but the eyelid)

Question 20

What vessels do you used for a bier block of the distal limb?

Answer 20

Digital vessels or dorsal common digital vein but either will be a blind stick with an 18-20G or 19-21G butterfly. Use lidocaine 25-30 mL per foot

Question 21

After a digit amputation (mid P2), what should you do?

Answer 21

Block and bandage the foot, antibiotics (nuflor) and NSAID (start with Banamine and switch to meloxicam )

They should be in a small pasture or stall for 3-4 weeks then recheck 5-7 days and blocks stays on for 3-4 weeks