Local/Regional Anesthesia

Question 1

What are some of the benefits of choosing local anesthesia over general anesthesia?

Answer 1

(Ruminants are poor candidates for general anesthesia, general anesthesia is expensive, and there is a lower risk of toxic effects if you pursue local anesthesia)

Question 2

Why are ruminants poor candidates for general anesthesia?

Answer 2

(Regurg, bloat, muscle damage/compartment syndrome)

Question 3

What is the duration of action for lidocaine?

Answer 3

(1-3 hours)

Question 4

What is the duration of action of bupivacaine?

Answer 4

(Up to 6 hours)

Question 5

What are the toxic doses for lidocaine in cattle versus small ruminants?

Answer 5

(Cattle → 10 mg/kg, small ruminants → 5mg/kg)

Question 6

The potency and duration of activity of local anesthetic can be increased by adding what drug?

Answer 6

(Epinephrine)

Question 7

What is the mechanism of action of lidocaine?

Answer 7

(Lidocaine blocks the fast voltage-gated sodium channels in neuronal cell membranes and with enough blockage, those sodium channels will not open and an action potential will not be generated)

Question 8

What needle size and length should be used for an inverted L block?

Answer 8

(18g, 1.5 inch, may need longer for fat cattle)

Question 9

Why are inverted L blocks not a first choice in small ruminants?

Answer 9

(You need a lot of lidocaine, can be hard to do with their lower toxic dose)

Question 10

What nerves are being targeted with a distal paravertebral block?

Answer 10

(T13, L1, and L2)

Question 11

What vertebrae are used as landmarks in a distal paravertebral block?

Answer 11

(L1, L2, and L4)

Question 12

How much lidocaine should be placed in each site for a distal paravertebral block in cattle?

Answer 12

(10-20mls, will end up being 60-120 mls of lidocaine total)

Question 13

What vertebrae are used as landmarks in a proximal paravertebral block?

Answer 13

(L1, L2, and L3, need should enter at the cranial edge of each vertebrae and you are targeting where the nerve root emerge from the intervertebral foramen)

Question 14

What spine space are you aiming for in an caudal epidural?

Answer 14

(S5-C1)

Question 15

Explain the hang and drop technique that is useful for caudal epidural anesthesia in cattle.

Answer 15

(If you are in the right spot with your needle, if you place a drop of lidocaine in the hub it will be drawn into the needle, then you can attach your syringe and anesthetic can be pushed easily)

Question 16

High volume caudal epidurals are a replacement for what other block that is used for abdominal, udder, and urogenital surgeries as well as c-sections?

Answer 16

(Lumbosacral block → still used in small ruminants and swine since high volume caudal epidurals are not successful in those species but good for cattle)

Question 17

How do you find the site of injection for a lumbosacral epidural?

Answer 17

(You go just caudal to the spinous process of L6 in swine or draw a line between the wings of the ileum and go just caudal to that line)

Question 18

What needle size and length is used for retrobulbar eye blocks?

Answer 18

(18 g 6 inch spinal needle)

Question 19

What nerves are blocked when using a Peterson eye block?

Answer 19

(Oculomotor, trochlear, abducens, and trigeminal)

Question 20

What are your two block options for teat anesthesia?

Answer 20

(Ring or V-block)